Re-Reconciling the Epistemic and Ontic Views of Explanation (Or, Why the Ontic View Cannot Support...

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Re-Reconciling the Epistemic and Ontic Views of Explanation(Or, Why the Ontic View Cannot Support Norms of Generality)

Ben Sheredos

Recent attempts to reconcile the ontic and epistemic approaches to explanation proposethat our best explanations simply fulfill epistemic and ontic norms simultaneously. I aimto upset this armistice. Epistemic norms of attaining general and systematic explanationsare, I argue, autonomous of ontic norms: they cannot be fulfilled simultaneously or insimple conjunction with ontic norms, and plausibly have priority over them. One result isthat central arguments put forth by ontic theorists against epistemic theorists are revealedas not only question-begging, but ultimately self-defeating. Another result is that a morenuanced reconciliation of the epistemic and ontic views is required: we should regardgood explanatory practice as a dynamic process with distinct phases of epistemic andontic success.

1. Debates Old and New: Reconciliation, Semantic Ascent and the Normative Turn.

In Salmon's (1978, 1982, 1984,1986, 1989/1990) initial division of ontic and epistemic accounts of

explanation, the ontic view (roughly) holds that explanations are those ontic structures in the world

which are responsible for the production of explanandum phenomena (e.g., the causes of phenomena),

whereas the epistemic view holds that explanation is concerned with making phenomena

understandable, predictable, or intelligible. The New Mechanists have held a lively debate over

whether explanation is epistemic (Bechtel & Abrahamsen 2005; Wright & Bechtel 2007; Wright 2012)

or ontic (Craver 2007), in roughly these senses.

Much of the debate can be read as a dispute over the nature of explanation, asking rather flatly:

is it an ontic structure in the world, or a cognitive achievement? Any such dispute must proceed

cautiously, however, to ensure that it does not become a merely semantic dispute. As illustration,

consider a statement Wright and Bechtel offered in rejecting the ontic view: “characterizing explanation

as non-epistemic is clearly problematic insofar as explanation is through-and-through an epistemic

practice of making the world more intelligible...”(2007, p.51). This claim about the nature of

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explanation is decidedly question-begging against the die-hard ontic theorist, who takes herself to have

in her conceptual scheme a rival, non-epistemic conception of explanation. A stronger line of argument,

which Wright (2012) has pursued, is to argue that any alleged non-epistemic conception of explanation

is essentially metaphorical and, moreover, parasitic upon an epistemic conception. In his view, to say

that non-human things in the world “explain” anything is implicitly to personify the objects in question,

treating them as if they were intentional agents who explain things epistemically. Wright's view is

offered as the converse of the semantic thesis he attributes to Salmon, that “the ontic sense of

explanation is most basic” (2012, p.380). If all ontic views were committed to this semantic claim,

Wright's argument would (if sound) undermine them all. There would not literally be any “ontic

explanations,” and so they would have no relevant nature to explore.

Despite Wright's efforts, the ontic theorists have not given up the ontic sense of “explanation.”

Instead, they have adopted an ecumenical stance, making a kind of semantic ascent (Quine 1960, §56).1

In his most recent writing on the subject, Craver (2014) explicitly recognizes and endorses all the

epistemic senses of “explanation,” and merely seeks to add an ontic sense to the list. No party to the

dispute is regarded as having special authority to stipulate what the “legitimate” senses of

“explanation” are, and crucially, the ontic view no longer endorses Wright's target, the semantic claim

that the meaning of “explanation” is basically ontic. Craver simply regards all of these senses as

“different” (2014, p.35). Instead, as Illari (2013) has clarified (and as I shall clarify further below) the

ontic theorist maintains a new, non-semantic kind of priority for ontic explanations.2 The result of this

semantic ascent is a significant reorganization of the debate whose effects are still being explored. An

important result is that arguments like Wright's are ineffective against this new breed of ontic theorist.

1 That is not to say that the ontic theorist is a Quinean in any robust sense: most still countenance “senses,” for example. 2 Wright has recently suggested that if the ontic camp abandons arguments over the semantics of “explanation,” they must

simply “concede the 'debate'” (2015p. 29, and see also fn.19). It is true that semantic debate which has most interested Wright is abandoned, but there remains much room for significant dispute.

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The ontic theorist cheerfully recognizes all the senses of “explanation” that the epistemic camp

proposes, and only seeks to employ an ontic sense as well, to refer to ontic structures in the world

which are responsible for phenomena. If the epistemic theorist presumes the authority to insist that this

is not permissible, that the ontic theorists' proposed ontic sense is illegitimate, they appear altogether

dogmatic. Arguments like Wright's are resisted as a kind of “definitional or usage stubbornness” (Illari

2013, p.243).3

One reasonable way for the epistemic camp to keep pace in the dispute is to make the semantic

ascent, granting that the ontic theorist may mean what they like. We may then take what I call the

“normative turn” in the debate, recommended by Illari (2013).4 Instead of arguing about the semantics

of “explanation,” we inquire directly after normative constraints on scientific explanatory practices,

seeking to clarify which properties make scientific explanations good. By being inclusive about the

meaning of “explanation,” we can have a productive dispute regarding what good explanation amounts

to. As pioneers of the normative turn in this debate, Craver and Illari have sought to reconcile the ontic

and epistemic camps, proposing that an ideally good explanation is one that simply fulfills epistemic

and ontic norms simultaneously – where the ontic norms specify what they mean to build into an ontic

sense of “explanation.” This new, reconciliatory ontic view promises a resolution of longstanding

debate, and will thus be welcomed by many. The way for the epistemic camp to gain any ground is not

to dispute that one can use the term “explanation” to refer to ontic structures, but rather to undercut the

ontic camp's own motivations for doing so. The epistemic theorist should seek a less impartial

reconciliation which minimizes the utility of the ontic sense. At the limit, the epistemic theorist might

3 Wright (2015) does not respond to this challenge, and continues to maintain that any ontic sense of “explanation” is “metaphorical,” “frivolous,” “bizarre,” etc. He still seeks to undermine all varieties of the ontic view by undermining Salmon's historical conception. The new vanguard of the ontic view will likely not be persuaded, though I take Wright's work to complicate any casual and unreflective endorsement of the historical views of Salmon.

4 The general idea of what I call the “normative turn” is by no means a unique development, but Illari has urged its endorsement most clearly as a development within the epistemic-ontic debate. For a similar view of philosophy of explanation more generally, see for example Weber et al. (2013, esp. ch.2).

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seek to argue that all good-making properties of explanations as they occur in scientific practice are

captured by epistemic norms, and thus that the ontic sense of “explanation” does no work.5

As I read van Eck (2015), he provides an example of how epistemic theorists might legitimately

defend a less impartial reconciliation. He makes the semantic ascent, avoiding “futile discussion on

terminology” (2015, p.10). He takes the normative turn, pursuing an “analysis of constraints on

explanatory power” (ibid., p.10). He thereby positions himself to argue against the reconciliatory ontic

view on its own terms. He then argues that, with respect to mechanistic explanations at least, epistemic

norms of identifying mechanisms' causal roles have a kind of global priority over fulfilling ontic norms:

these epistemic norms must be fulfilled before we can fulfill any ontic norms. Further, he argues that

these epistemic norms have a kind of autonomy from ontic norms in some cases: mechanistic

explanations of now-extinct mechanisms are only cogent if we recognize that a successful account does

not require fulfilling certain ontic norms (i.e., regarding the non-existent mechanism). The conclusion

to draw would be that explanation is “fundamentally epistemic,” even if ontic norms have a role to play

(ibid., p.15). van Eck's argument is ambitious by defending the priority of epistemic norms in every

mechanistic explanation. It is somewhat limited since it only concerns mechanistic explanations.

My goal is to raise the stakes even further, joining van Eck (2015) in arguing for a less impartial

reconciliation which favors the epistemic view. Like him, I want to defend a kind of priority and

autonomy of some specific epistemic norms over ontic norms. My aims are less and more ambitious

than his: less in that I do not seek to secure a global priority for these epistemic norms in all cases, and

more in that I pursue a general argument against all recent ontic views, not just mechanistic views.

I will shortly say more about how the paper and the argument proceeds. But let me note in

advance that much of the paper will, like van Eck's, engage with the literature on mechanistic

5 Compare Weisberg (2013, p.19) on disputes at the “epistemic level” in the philosophy of scientific modeling practices.

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explanation. This is only because I seek to underscore that many of the premises required for my

argument are already endorsed by the ontic mechanstis. I employ two strategies to demonstrate the

generalizability of my argument to a variety of non-mechanistic views. (1) later, I show how my

argument undermines Strevens' (2004; 2008) non-mechanistic, ontic view. (2) I locate many of the

claims I need for my argument in Michael Weisberg's work on modeling practices. Weisberg's corpus is

neutral ground in the epistemic-ontic debate: no camp has claimed it for their side, and he declares no

allegiance to either camp.6 Yet once we focus on the practical norms which govern good explanation,

Weisberg's work on modeling practice is centrally relevant, and deserves greater attention than it has

received in the dispute. Here I shall generally indicate connections to Weisberg's work in footnotes, so

as not to derail my main engagement with the extant epistemic-ontic debate.

The paper proceeds as follows. First (§2) I further explicate the recent ontic view as asserting

the normative priority of ontic norms. On this view, an explanation cannot be fully successful unless it

is fundamentally constrained to be true or accurate (to get things right) and getting things right is not

itself fundamentally constrained or determined by any epistemic norms. van Eck contests this, and so

shall I. I then (§3) defend the claim that all parties to the dispute should (as Craver does) countenance

epistemic norms of attaining general and systematic explanations. Drawing upon Craver's remarks, I

distinguish the scope of explanations (their applicability to multiple cases), from both (i) generality

(their invocation of categorical claims regarding classes of explananda and explanantia) and (ii)

systematicity (their specification of some principle of extrapolation for applying an explanation to

multiple cases). I clarify the epistemic norms of attaining general and systematic explanations, showing

why ontic theorists should (as Craver does) support them. Their chief value is that by fulfilling them,

6 Weisberg (2013) generally uses “explanation” in an epistemic sense (calling models explanatory), though he seems to tolerate an ontic sense (see, e.g., pp.94), finds nothing curious about,e.g., Strevens' view (p.101) and at times appears to deploy both ontic and epistemic senses at once (p.103).

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we unify explanatory practice, facilitate research, and make intelligible how explanations of

phenomena can apply to many distinct cases. They govern basic scientific reasoning and practice.

A successful reconciliation of the ontic and epistemic views must provide support for these

norms of generality and systematicity. But I argue (§4) that fulfilling epistemic norms of generality and

systematicity is in direct conflict with the global normative priority of ontic norms. I advance three

mutually-supporting lines of argument (logical, material, and practical) to show why epistemic norms

have priority in these cases, and why ontic accounts cannot support norms of generality and

systematicity without giving up the normative priority of ontic norms – i.e., giving up the reconciliatory

ontic view. In brief, unless one is a realist about universals, there is no ontic explanation to “get right”

in the way that the normative priority of ontic norms would require. A practice-oriented philosophy of

science allows an a posteriori realism about universals. Priority goes to epistemic norms: one posits

universals on the basis of prior success in attaining general and systematic explanations. The ontic

theorist's demand to “get things right” is thus shown to be vacuous in these cases, and the

reconciliatory ontic view's global thesis of the normative priority of ontic norms is shown to be false.

In (§5) I argue that Craver's arguments against paradigmatic endorsements of generality and

systematicity (e.g., unificationism) are question-begging and self-defeating: they leave the ontic

theorist with no analysis of generality and systematicity. I also clarify my positive view. Since

reconciliation cannot be attained by claiming that good explanations conjunctively and simultaneously

fulfill all ontic and epistemic norms, we should regard good explanatory practices as involving distinct

phases of epistemic and ontic success. While we are fulfilling some epistemic norms (e.g., of generality

and systematicity), they have priority, and we cannot simultaneously fulfill some ontic norms – and

vice versa. My approach to re-reconciling the epistemic and ontic views – what I call “heuristic

category theory” – proposes that explanatory practice involves a dynamic back-and-forth between

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fulfilling both kinds of norms: an extended practice of category-negotiation. Finally, I extend this

conclusion by showing that Strevens' distinct ontic account faces all the difficulties of Craver's. The

problems I point out arise from systemic features of current ontic views. I conclude (§6) with remarks

on the future of the epistemic-ontic debate, revisiting how my claims relate to those of van Eck.

2: The Normative Priority of Ontic Norms.

In this section, I draw upon Craver's work (§2.1) to provide a general analysis of recent ontic views of

explanation (§2.2) that assert the normative priority of ontic norms over other norms of explanation. I

argue against this view below.

2.1: Craver's Ontic View.

Craver (2014, pp.30-34) proposes a kind of “semantic ascent” in the epistemic-ontic debate,

countenancing four senses of “explains” and cognates (in English). Infrequently, where no distinction is

required, I simply speak of “explanation.” However, “lumping” together these four categories is an

oversimplification that fosters confusion. Hence I shall generally be using subscripts to distinguish all

four senses, which I introduce by providing Craver's own examples:

ExplainsCOMM – “Jon explains the action potential (Communicative Mode)”ExplainsONTIC – “The flux of sodium (Na+) and potassium (K+) ions across the neuronal

membrane explains the action potential (Ontic mode)”ExplainsTEXT – “The Hodgkin-Huxley (HH) model explains the action potential. (Textual

Mode)”ExplainsCOG – “Jon's mental representation of the mechanism of the action potential explains

the action potential (Cognitive mode).”

Craver's expansive conception of explanationsTEXT includes a variety of models, written prose,

diagrams, and much else as “texts.”7 As Craver points out, having an explanationCOG might be re-

expressed as understanding some phenomenon. I sometimes collectively label the communicative,

7 Note that he whole category of explanationsTEXT might be replaced with a less restrictive conception of models, and the category of explanationsTEXT might fruitfully be further articulated in light of the distinction between models and their description. See Weisberg (2013, pp.15ff).

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textual, and cognitive senses as “explainsC/T/C” (and cognates), since they are closely related. Any

explanationCOMM must proceed through a representational medium, and will thus involve

explanationsCOG or explanationsTEXT or both. As Craver notes, the main demarcation between

explanationsONTIC and explanationsC/T/C is that the latter are broadly “epistemic” insofar as they depend

upon the existence of intentional agents (2014, p.35).

Craver does not maintain that any one sense of “explanation” constitutes the basic meaning of

the term: he regards each as independent and legitimate.8 Despite this, Craver holds that

explanationsONTIC themselves are in a way, more fundamental than any variety of explanationC/T/C. This

is because Craver endorses what I call the “normative turn” recommended by Illari (2013).9 Craver

frames his view in terms of the success conditions of explanationC/T/C, claiming that there is an

“asymmetric direction of fit” between the varieties of explanation, such that “the adequacy of our

communicative acts, our scientific texts, and our mental models depends in part on whether they

correctly inform us about the features of the world that cause, produce, or are otherwise responsible for

the phenomenon we seek to explain” (ibid., p.36, my ital.). Craver's claim is not that this as built into

the meaning of “explanationC/T/C,” but rather that this is what we practically demand of explanationsC/T/C

before counting them as fully successful. Craver admits that an explanationC/T/C can be partly successful

in virtue of meeting non-ontic, epistemic conditions: it might be in-principle understandable (relative to

an audience), or be actually understood (by a given audience). But he insists that to be fully successful,

it must be correct: it must convey information about an explanationONTIC.10

Once we've pinned down the facts about an explanationONTIC, what counts as epistemic success

8 Craver (2014) wields syllepsis/conjunction reduction to support this claim. Wright (2012) offers a rejoinder, but I agree with Illari (2013) that this will not move the ontic theorist; the productive debate concerns norms of explanation, not who gets to legislate the semantics of “explanation.”

9 Craver has confirmed this in personal communication to Illari – see her (2013, p.241).10 Note that the epistemic camp has sometimes denied this, by permitting false-but-intelligible explanationsC/T/C to be fully

successful. See, e.g., Bechtel & Abrahamsen (2005, p.425), and more recently de Regt (2014). So the new ontic view is still readily distinguished from robust epistemic views, which shows that there is still much room for debate.

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can continue to vary wildly. Successfully explainingC/T/C facts about the mechanisms of action potentials

to an undergraduate may require all sorts of epistemic workarounds and scaffolding, whereas

successfully explainingC/T/C those same facts to an expert neuroscientist may be straightforward. What

counts as epistemic success depends upon one's audience and one's aims. ExplanationsONTIC are

insulated from such contextual success conditions; indeed, they have no success conditions whatsoever:

“Ontic explanations are not texts: they are full-bodied things. They are not true or false.They are not more or less abstract. They are not more or less complete. They consist in alland only the relevant features of the mechanism in question. There is no question of onticexplanations being 'right' or 'wrong,' or 'good' or 'bad.' They just are” (ibid., p.40).

ExplanationsONTIC (i.e., things in the world) have no normative dimensions, yet the full success of all

explanationsC/T/C depends upon meeting an ontic norm of getting things right (in conjunction with

meeting highly variable, epistemic success conditions). ExplanationsONTIC are held to be always

explanatory, since it is held that they just do account for phenomena. What is “good” as explanatoryC/T/C

practice is held to ultimately bottom out in what is true. I refer to this as the thesis of the normative

priority of ontic norms over epistemic norms.11

2.2: The Ontic View in General.

A framing of any ontic view (not just an ontic conception of mechanistic explanation) can be drawn out

of Kaplan & Craver's (2011) claim that a norm of “model-to-mechanism-mapping” (“3M”) governs the

success of explanationsTEXT (e.g., dynamical and mathematical models) in neuroscientific fields:

“(3M) In [fully] successful explanatory models in cognitive and systems neuroscience (a)the variables in the model correspond to components, activities, properties, andorganizational features of the target mechanism that produces, maintains, or underlies thephenomenon, and (b) the (perhaps mathematical) dependencies posited among thesevariables in the model correspond to the (perhaps quantifiable) causal relations among thecomponents of the target mechanism” (Kaplan & Craver, 2011, p.611).

That is: models only (fully) successfully explainTEXT a phenomenon's occurrence if variables in the

11 Compare Weisberg on “representational fidelity” (2013, p.41) and “I-CAUSAL” as a practical norm (ibid., pp. 107ff).

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model, and modeled relations between them, can be “mapped” directly to ontic structures (i.e., things)

which explainONTIC (cause, constitute, or are otherwise responsible for) the phenomenon's occurrence. If

such a mapping is not available, the explanationTEXT cannot be correct, and cannot be fully successful.12

The basic, reconciliatory ontic view can be understood as an extension of (3M). Again, in order

to avoid oversimplification, we must address all four senses of “Explanation,” and this means a general

statement of the ontic view will necessarily be somewhat unwieldy. With this in mind, we may provide

a general gloss on an ontic conception by taking four large steps. First, extend (3M)'s scope beyond

cognitive and systems neuroscience to propose a constraint for any domain of inquiry. Second,

parenthesize Kaplan & Craver's commitment to mechanisms: any ontic structures that an ontic theorist

cares to offer as explainationsONTIC will do. Third, permit an explanationONTIC to involve more exotic

dependency relations than just causal relations, so long as such dependencies are bolted down in the

factual world. Finally, extend (3M)'s scope beyond explanationsTEXT, demanding a “mapping” to ontic

structures for the full success of all explanationsC/T/C. A full statement of this proposed norm of

“ExplanationC/T/C -to-ExplanationONTIC-Mapping” (EEM) runs:

(EEM) In fully successful explanationsC/T/C of some phenomenon,(a) the

terms in the model offered as explanationTEXT, and/or13 descriptions in the communicative act offered as explanationCOMM, and/or contents of mental representations serving as explanationCOG

correspond to (e.g. convey information about)14 the explanationONTIC (e.g., the components, activities, properties, and organizational features of the target mechanism) that produces, maintains, or underlies the phenomenon,

and

12 More strongly, the ontic theorist might demand we specify the “mapping,” making clear what the ontic explanation actually is. This stronger criterion might track popular talk in the ontic camp about “exhibiting” an ontic explanation – but see Wright (2015) for challenges to this view.

13 The “and/or” allows (EEM) to cover mixed cases: e.g., Jon engaging in a communicative act of explanationCOMM and offering the HH model as an explanationTEXT of action potentials. Here two mappings must be coordinated.

14 Craver's more recent preference is to say that explanationsC/T/C “carry explanatory information about a phenomenon when and only when they describe the ontic explanations for those phenomena” (2014, p.28). This seems one way to specify the notion of “mapping,” so I mention it in (EEM) explicitly. But other (and multiple) specifications may be available or required. To leave this open (and for convenience) I speak mainly of “mappings.”

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(b) the (perhaps mathematical) dependencies posited among those terms in the model, and/or those descriptions offered in the communicative act, and/or those contents of mental representations

correspond to (e..g carry information about) the (perhaps quantifiable) dependency relations in the explanationONTIC (e.g., among components of the target mechanism).

One important caveat should be noted.15 Ontic theorists typically permit an idealizing explanationC/T/C to

include false assumptions about an explanationONTIC. A fully-successful explanationC/T/C might “convey

explanatory[ONTIC] information in virtue of making false assumptions that bring certain [other] truths

about the ontic explanation to light” (Craver 2014, p.50). The mapping to ontic structures required by

(EEM) need not be exhaustive, and can rather be selective.16 An explanationC/T/C is permitted to

partially flout (EEM) if this facilitates partially fulfilling (EEM). Even in this concession, the basic

commitment to the normative priority of ontic norms is made plain.

In slogan form, (EEM) asserts: “No full explanatoryC/T/C success without explanationsONTIC!”

Once we make a semantic ascent – abandoning any claim to the semantic priority of “explanationONTIC”

– and take the normative turn, (EEM) is a plausible way of maintaining that there is a kind of

fundamentality associated with explanationsONTIC, namely the normative priority of ontic norms

This view also captures Illari's (2013) proposal to unify the epistemic and ontic approaches.

Though Illari sometimes aims to resist granting “fundamentality” to the ontic view (see her §3), her

integrative account relies upon the normative priority of ontic norms, as defined here. Her concluding

remark regarding the integrative view is that: “The real achievement of mechanistic (and possibly other

forms of) explanation is satisfying both ontic and epistemic constraints simultaneously, to get a story

constrained by all the empirical contact with the world that ingenuity can design” (2013, p. 17). This

15 Marta Halina deserves thanks for making clear to me the importance of this caveat.16 See also Kaplan & Craver (2011, p.612) and likewise Strevens (2004, 2008) throughout. For handy distinctions between

varieties of idealization, some of which have not yet been explicitly incorporated into the epistemic-ontic debate, see Elliot-Graves & Weisberg (2014). See further Weisberg (2013, pp.90ff) on target systems and calibration, and also ch.6.

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proposed reconciliation depends upon the suggestion that the epistemic theorist “doesn't want to claim

that what is really in the world doesn't matter,” (ibid., p.14) where what is really in the world (i.e.,

explanationsONTIC) just is, and is not constrained by epistemic norms. Or as she puts the claim more

strongly elsewhere, while discussing mechanistic explanation: “even epistemic explanation in terms of

mechanism description is still parasitic on the actual existence of mechanisms ” (Illari & Williamson

2013, p.280). This presumes the normative priority of ontic norms and falls under (EEM).

The central thesis of this paper is that, for some explanations, (EEM) is either false, or else the

demand to fulfill it is vacuous, since the demand imposes no independent constraint upon

explanationC/T/C. Either way, the normative priority of ontic norms is to be abandoned in such cases. The

decisive claim against (EEM) is that in general or systematic explanationsC/T/C, the truth about things in

the world cannot independently matter in the way the ontic view requires: there is no normative priority

of ontic norms. Before I can make this claim, I need to clarify the distinction between representations'

scope, and their generality and systematicity. That is the task of the next section.

3: Scope vs. Generality & Systematicity.

In this section the different forms of epistemic explanation (explanationsC/T/C) must be carefully

distinguished, since I shall be invoking various commitments regarding different forms of

explanationC/T/C – especially regarding explanationsTEXT. These are already endorsed by disputants,

ensuring that I beg no questions against the ontic view. Nonetheless the claims I secure here are

intended to be generally acceptable, as I shall underscore in footnotes throughout. Likewise, in this

section I focus on mechanistic accounts of explanation since the claims I need for my argument have

been drawn already in this literature, in connection with the epistemic-ontic debate. Yet the argument I

will raise is generalizable against non-mechanistic ontic views, as I shall show in §5 below.

I first (§3.1) follow Craver & Kaiser (2013) in distinguishing generality from mere scope.

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Whereas Craver ostensibly draws the distinction to avoid certain appeals to generality, I argue (§3.2)

that generality is still a norm of explanation to which ontic theorists should be committed and show that

Craver is so-committed. I then (§3.3) employ Craver's own distinction to clarify the “systematicity” of

general explanationsC/T/C, and show the epistemic norm of attaining general and systematic explanations

to be widely recognized. The upshot is that the reconciliatory ontic theorist owes us some analysis of

how the ontic view can support norms of generality and systematicity. In §4 below, I argue that the

epistemic norm of generality and systematicity is actually inconsistent with (EEM).

3.1: Scope vs. Generality in explanationsC/T/C (especially explanationsTEXT).

An explanation'sC/T/C scope is commonly regarded as the set of cases to which it is applicable with some

explanatory force. For present purposes, an explanation's scope is the range of ontic structures to

which the explanation can be “mapped” in accordance with (EEM).17

An explanationC/T/C which is general has broad scope (though we will see below that not all

explanationsC/T/C with scope are general). An explanationCOMM is explicitly general if it is cast in

categorical terms. For example, Jon might explicitly offer an account of all events in the category of

action potentials, or of all action potentials in a category of neurons, a category of organism, or

occurring under a category of conditions. The explanation'sCOMM scope is the scope of quantification,

the extension of the relevant category. Similarly, an explanationCOG is general if it involves mental

representations with categorical content (e.g., the general concept of ACTION POTENTIAL, rather

than, say, particularistic images or percepts of particular action potentials). The explanation'sCOG scope

is the extension of the representation. (I assume nothing regarding how concepts attain their generality,

17 Given the four distinct senses of the term “explanation,” we could fix multiple notions of “explanatory force” and thus multiple corresponding notions of “scope.” For example, an explanationCOMM of action potentials which “maps” neatly tomechanisms in pyramidal cells will not “map” neatly to those in fast-firing Purkinje cells. We might say that while the explanationCOMM has little explanatoryONTIC force for Purkinje cells, and does not have them in its “ontic scope,” still it has some explanatoryCOMM force for Purkinje cells (offering a rough and revisable understanding of their action potentials) and has them in its “communicative scope.” I set these issues aside.

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nor how sharp category boundaries might be). Frequently, the generality of an explanationC/T/C is not

explicit in its surface structure.18 In Craver's example (see §2.1 above) Jon is said to offer an account of

“the” action potential. Which one? Likely none in particular. If the intention is to offer a general

explanationCOMM, Jon could begin make its scope explicit by specifying the category of cases under

discussion (e.g., “all action potentials,” or “all action potentials in pyramidal cells,” etc.).

So in prototypical cases, the generality of explanationsCOMM and explanationsCOG will determine

their scope. The status of explanationsTEXT is more complicated, and supports a clearer distinction

between scope and generality. Craver & Kaiser (2013) suggest that explanationsTEXT may have scope

without generality.19 They begin with Bechtel & Abrahamsen's (2005) characterization of biological

theories. In biology, theories are often constructed by working out an explanationTEXT (model) of some

particular mechanism, offering it as an exemplar for understanding some broader class of

mechanisms.20 Since there is variation between mechanisms, they stand only in relations of family

resemblance to one another, making unlikely a classical “definition” which specifies a set of necessary

and sufficient conditions to determine the model's scope. Bechtel & Abrahamsen draw upon non-

classical psychological theories of concepts and categorization (cf. Rosch 1975, 1978) to sketch an

account of generalization in biology: biologists may rely on intuitive understandings of relevant

similarities to the exemplar to determine fuzzy category membership under a general concept, without

specifying any explicit metric of similarity or definitive condition of membership (2005, p.428).

Generality of mental representation (explanationCOG) is here presupposed, and the operative logical

relation is the subsumption of tokens under a general category. Similarity to an exemplar determines

18 On all these points, compare Weisberg on “intended scope” (2013, pp.39ff) and on implicit and explicit “assignment” (ibid., pp.69-70) as part of modelers' “construals”

19 Locke has an analogous view of explanationsCOG AS abstract ideas: Essay Concerning Human Understanding, II.XI.§9.20 Compare Weisberg (2013, ch.5) on “target-directed modeling” – the real exemplars discussed by Bechtel & Abrahamsen

are not to be confused with what he calls “idealized exemplars” (ibid., pp.18-19).

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concept boundaries, which precedes and guides theory construction via extrapolation of the model from

the exemplar to other category members. Such guidance can be heuristic, fallible, and revisable.21

Craver & Kaiser place different emphasis on this view, noting that an explanationTEXT need not

itself be general to have scope:

“On such an exemplar view, generalization is extrinsic to the mechanistic models... themodel need not contain general statements or general representations at all... thegenerality of such a mechanistic model is a matter of its scope of application and notsomething that must be represented within the model itself” (2013, p.134).

For example, one might build an explanationTEXT (model) of a particular case and then use it as an

explanationTEXT of other particular cases.22 The model itself has no general or categorical content: in

each application it represents nothing but the token mechanism to which it is applied.23 If it is not

applied, and is left “schematic” or gappy, then strictly speaking it represents nothing.24 Yet it has scope

in virtue of being applicable to (“mappable” to; instantiable by) multiple mechanisms. The operative

logical relation is the instantiation of singular terms, not subsumption under a category.

Employing this idea of a non-general model which has scope, Craver and Kaiser deny that

categorical knowledge of regularities is “necessary for one to extrapolate mechanistic knowledge”

(ibid., p.132), suggesting that scientists might set about extrapolating a model to new cases (exploring

its scope) without any conception of the category of cases to which the model applies. In that case

(unlike Bechtel & Abrahamsen's view) generality of a representation does not precede determination of

21 Given well-known issues (cf. Goodman, 1972), I do not presuppose that Bechtel & Abrahamsen's (and Craver & Kaiser's, see below) similarity-based account is the correct analysis of generality. What I share is the view that some account of generality must be provided to account for any model's scope. Appeals to similarity face difficulties in meeting this demand by setting out plausible conditions of category membership. This does not diminish the demand. For a recent, systematic proposal for how to meet the demand by appeal to similarity, see Weisberg (2013).

22 Compare Weisberg (2013, p..75ff) on model construction and “construal change.”23 Compare Weisberg's distinction of target-directed models (2003, ch. 5) from modeling a generalized target (ibid., ch.7).24 The distinction between mechanism sketches and schemata (Machamer, Darden & Craver 2000) adds some nuance here,

but brings with it much confusion. The sketch/schema distinction does not properly respect the logical distinction between subsumption under a category and instantiation of singular terms; I avoid invoking it to keep the focus squarely on this logical issue.

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the model's scope. I follow Craver and Kaiser in endorsing this distinction between scope and

generality, and in permitting the extrapolative use of models in a way that does not presuppose

generality. But we cannot entirely avoid appeals to generality on Craver & Kaiser's view.

3.2: Systematicity and Making Scope Intelligible: Heuristic Category Theory.

In responding to Bert Leuridan (2010), Craver & Kaiser are adamant that the mechanist does not seek

to abandon general explanationsC/T/C tout court, saying that “no mechanist has ever made such claims”

(cf. 2013, p.127). Their aim is to show how the mechanistic approach can enrich our understanding of

the role of generalizations science. Let us examine their view.

Craver & Kaiser adopt Leuridan's terminology, speaking of “p-law statements as descriptions of

stable and strong regularities that can be used to predict, explain and manipulate phenomena” (ibid.,

p.128). The regularities which are described by “p-law statements” are called “p-regularities” or, if one

has a robust metaphysical conception of laws, “p-laws.” In advancing their proposal, they offer a

concise example of how mechanists can explain such regularities:

“...consider the possibility that most p-regularities are stable and strong because they areproduced or maintained by mechanisms... Why might [Thomas H.] Morgan haveexpected the apparent exceptions he discovered in his lab to apply outside the lab in otherorganisms? The simple answer is this: he expected the mechanisms of heredity outsidethe lab and in other organisms to be more or less similar to the heredity mechanisms atwork in his Drosophila. The p-laws of heredity are stable and strong precisely becausethere is an underlying mechanism (e.g., involving crossing over and replication ofchromosomes) that explains[ONTIC] them” (ibid., p.134, my ital. except the Latin).

Note the ontic construal of “explanation” here: the passage begins with the claim that mechanisms

produce or maintain a regularity, and ends with the claim that a mechanism is the “explanation” of a

regularity. Note also in italics a striking vacillation over whether it is many token mechanisms which

underwrite a regularity (producing each instance of the phenomena which, collectively, exhibit a

regularity), or whether we should rather appeal to one mechanism which underwrites a whole regularity

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(as such). The former claim is consistent with Craver's mechanistic view: there are literally token

mechanisms in multiple token organisms. The latter claim is quite puzzling. What would it mean to say

that one mechanism produces regular phenomena of heredity in disparate organisms, times, and places?

Perhaps this is merely a slip, but I return to it in §4 below.

For now, I suggest that Craver & Kaiser's appeal to similarity here is best read as invoking the

very same non-classical theory of categorization to which Bechtel and Abrahamsen appeal. Craver &

Kaiser clearly attribute to Morgan expectations of similarities between many token mechanisms. What

they mean to be saying, I suggest, is that Morgan had a (non-classical) general explanationCOG which he

used to make intelligible the predicted scope of his model. Absent such an appeal to an explanationCOG,

there seems to be no account on offer here of Morgan's extrapolation of the model: without such an

explanationCOG his (and anyone else's) practice of prospective extrapolation would be unintelligible, and

his (and anyone else's) expectation would collapse into a mere wish for the brute coincidence that the

model would happen to apply to many mechanisms.

What has become of Craver & Kaiser's foregoing claim, that categorical knowledge of

regularities is not “necessary for one to extrapolate mechanistic knowledge” (ibid., p.132)? A

simplistic answer would be that Morgan's mere expectations do not count as “knowledge,” but this

would still fail to distinguish their view from Bechtel & Abrahamsen's. Let me suggest a more robust

and internally consistent reading of Craver & Kaiser's claims. This robust reading can be exemplified in

two schematic cases. First, imagine a case where many scientists independently develop many

explanationsTEXT (models) of diverse particular cases. After this is done, they realize that there are, e.g.,

formal similarities between the models, even though none of them has any general content. The

similarities are so striking that they regard them as the same model, and as a result, they note

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previously unrecognized similarities between the items in its scope.25 Second, imagine a case where a

model built for one case is simply found to apply to another – in an unanticipated stroke of luck, as it

were. Once we have reached this point in either scenario, the fact that the model has unanticipated

scope can enable the formation of a representation (explanationCOG) with (non-classical) general content.

Crucially, the formation of this representation allows us to do, in a backward-looking way, precisely

what Morgan's general representation enabled him to do in a forward-looking way. It enables us to

make intelligible the previously-established scope of a model. Whether or not a model itself has general

content, if it does have scope, then ultimately the thinker who uses it to explainTEXT multiple cases

ought to seek some general mental representation (explanationCOG) of the category of cases to which the

model applies. Otherwise, the model's scope would have to be regarded as a brute coincidence.

In practice, I submit, the use of models vacillates between the use articulated by Bechtel &

Abrahamsen (presumptive generality guiding predictive extrapolation) and the second conception

which I have worked out for Craver & Kaiser (evaluation of de facto extrapolation's success feeding

back to constrain generality).26 I have described such a case of category-negotiation elsewhere in a

different connection (REDACTED). Sullivan (2014) has raised a similar point regarding the

“stabilization” of psychiatric kinds. One could say, in the spirit of McCauley & Bechtel's (1999, 2001)

Heuristic Identity Theory, that scientists employ a (highly implicit) “heuristic category theory.” A

category is formed which is suitable for making intelligible the merely predicted, or previously-

established, scope of a model; if the model turns out to apply in an unexpected way, the category is

25 In Weisberg's more fine-grained terminology: they realize that many models share a model description (2013, pp.34ff), and they construe them as having the same intended scope (ibid., pp.40ff). They reach this view in part by clarifying the models' shared representational capacities (ibid., pp.42ff), and in part through construal setting (ibid., pp.116-117).

26 Compare Weisberg's claims: (i) that model descriptions need not precede construction of models (2013, p.38); (ii) that modeler's construals of a model can change over time (ibid., p.77ff); (iii) that modeling involves fine-tuning the selection of the model's target over time (ibid., p.92); (iv) that calibration of a model occurs in a feedback process (ibid.,pp.94-95); and (v) that modeling practices involve a dynamic back-and-forth between model-building and collection of data (ibid., p.154).

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revised accordingly, and so on. In any case, making intelligible why a model has scope will eventually

demand formation of a general category. Craver & Kaiser implicitly recognize this in the forward-

looking case of Morgan's extrapolation; things are no different in the backward-looking case. And

while I have only illustrated the case here with regard to explanationsTEXT or models, the same is

plausibly true of any explanationC/T/C with scope: it is not enough to see that an explanationC/T/C has

scope, we want to understand why it has scope, and this requires trafficking in general representations

of categories. The formation of a general representation of a category of cases to which an

explanationC/T/C applies introduces the systematicity of explanationsC/T/C.

I call an explanationC/T/C systematic (or, systematizing) if it states or otherwise specifies

(explicitly or implicitly) some principle of extrapolation that makes intelligible the explanation'sC/T/C

applicability to cases in its scope.27 Where an explanationC/T/C is itself general (categorical), the

systematicity of the explanationC/T/C is explicit: the principle of extrapolation is determined by

principles of (perhaps non-classical) category-membership.28 The explanationC/T/C is presumed

applicable to any member of a category, qua member of that category. If, as Craver & Kaiser maintain,

some explanationsTEXT (models) with scope are not themselves general, then they are also not

themselves systematic. Generality and systematicity are outsourced to a mental representation

(explanationCOG) which thinkers use in (or attain through) extrapolating the model, and which they use

to make intelligible a model's scope by specifying a category of cases to which it applies. As Craver &

Kaiser's examination of Morgan helps to partially clarify, to forego an appeal to systematic

explanationC/T/C is to forego any analysis which makes practices of prospective extrapolation

intelligible, since this requires an account of how a model's scope is intelligible. Insofar as all parties

27 In Kantian mode: systematicity requires a rule of unity which unites members under a category. All this is nicely articulated in Weisberg's (2013) conception of a “construal.”

28 See again fn. 20.

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agree that explanationsC/T/C ought to attain increased scope (explanatory force) where possible, all

should agree that there is a corresponding norm of making that scope intelligible.

I have distinguished generality and systematicity to leave open the possibility that they may

come apart. But in what follows, I shall be focused on prototypical cases where they ride together. I

shall shall speak accordingly of “generality and systematicity.”

3.3: Generality & Systematicity as a Prototypical Epistemic Norm

What I have articulated as the norm of generality and systematicity is not just any epistemic norm of

explanationC/T/C, but rather a flagship case. It can be seen as central to the deductive-nomological or

“covering law” account (Hempel & Oppenheim 1948; Hempel 1965), and the later “unificationist”

program (Friedman, 1974; Kitcher 1981, 1989). These are the loci classici for Salmon's rendering of

the epistemic view, and are likewise employed by Craver (2007) and Strevens (2004, 2008) as

paradigms of the epistemic view. Outside the epistemic-ontic debate, others have held that generality

and systematicity is the sine qua non of properly scientific explanation, distinguishing it from merely

conjunctive fact-gathering (Kuhn 1962/1996, p.16; in a case close to home for mechanists, see also

Bogen & Woodward 1988, esp. p.325). I have just provided an analysis of why the ontic theorist ought

to be committed to these norms, even granting that not every explanationC/T/C need itself be general to

have scope. The crucial value of generality and systematicity is that it makes intelligible any

explanation'sC/T/C scope, unifying explanatoryC/T/C practices, and facilitating research and testing by

delineating a category of cases to which any explanation is presumed applicable. It is part and parcel of

basic scientific reasoning. Any reconciliation of the epistemic and ontic camps (and indeed, any

plausible view) must provide support for these norms of explanationC/T/C.

Craver and Kaiser themselves clearly display commitment to this norm, as shown above. If they

did not, they would have no way of maintaining that the mechanist can account for general

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explanationsC/T/C of regularities, they would leave the scope of any explanationC/T/C unintelligible, and

they would render, e.g., Morgan's prospective extrapolation of his own model to new cases an

unintelligible wish for a brute coincidence to hold between known cases and unknown cases. The

normative turn permits the ontic theorist to recognize the norm of generality and systematicity while

still maintaining that there are ontic norms. The question, we shall see, is how precisely the ontic

theorist can seek to support the norm of generality and systematicity. I now argue that the ontic view, as

expressed in (EEM), cannot properly countenance norms of attaining generality and systematicity:

recognition of this norm is inconsistent with the normative priority of ontic norms.

4: The Normative Priority of Epistemic Norms in attaining Generality/Systematicity.

Let me begin this section with a brief, “softening-up” argument. (EEM) is most apt as a constraint

upon singular explanationsC/T/C of a token explanationONTIC that produces a token phenomenon on some

particular occasion. (EEM) can also be extended to address an explanation's (mere) scope, in the

following manner. A non-general model (explanationTEXT) has scope if It has be extrapolated to a range

of particular cases: this plausibly means that (EEM) has been variably fulfilled, the model “mapped” to

numerous explanationsONTIC.

This does not fulfill the norm of generality and systematicity, rather it is the harbinger of the

normative demand for generality and systematicity. Recognizing that a model has scope, one has the

merely conjunctive recognition that the model applies (“maps”) to multiple explanationsONTIC. The norm

of generality and systematicity demands, further, that one now specify a general principle of

extrapolation, making the model's scope intelligible. This strongly suggests that fulfilling the norm of

generality and systematicity involves going beyond (EEM).

In the remainder of this section I argue in detail that attaining such general, explanatoryC/T/C

representations is incompatible with the normative priority of ontic norms. A first, mostly formal line of

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argument (§4.1) demonstrates the separability of the two kinds of norms: logically, there is no need to

suppose that ontic norms should be fulfilled in attaining generality and systematicity. A second,

material line of argument (§4.2) makes clear what seems to be the only way for the ontic view to

countenance the norm of generality and systematicity while upholding (EEM): to adopt some form of

Aristotelianism about universals. A third, practical line of argument (§4.3) shows that this “solution”

plausibly flouts the normative priority of ontic norms: no practice-oriented philosopher of science

should posit the existence of Aristotelian universals unless our explanatory practices have already

succeeded in fulfilling norms of generality and systematicity, which means that these epistemic norms

have priority. I conclude that ontic accounts cannot support the norm of generality and systematicity.

4.1: The Formal Line of Argument.

There is a basic logical distinction between scope and generality. Since Frege, formal logics have thus

appropriately marked the distinction between quantifiers and predicates ('s, 's, and F's), on the one

hand, and singular terms (x's or a's) on the other. A singular or particularistic representation (say, a

variable in a model) might “map” to a (component of a) token ontic structure as required by (EEM). As

noted in §3.1, the logical relation at work in such a “mapping” is the instantiation of a singular variable

(or the fixing of the denotation of a singular term). General and systematic explanationsC/T/C do not

“map” to any particular ontic structure in just this way: they involve representations of entire

categories, as such, and the logical relation at work is subsumption.29 What is at issue is not that (EEM)

requires an exhaustive “mapping” to all the particularities of an explanationONTIC, for it does not. As

noted in relation to idealizing explanations (§2.2 above), (EEM) only requires mapping selectively to

some ontic particularities and not others. Generality, in the sense I am concerned with, is not equivalent

to idealization. (More on this in §5.2 below.) What matters is that (EEM) requires mapping every

29 Compare Weisberg (2013 pp.116-117) on the different construals which are required in target-based modeling versus generalized modeling.

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explanationC/T/C to some or other particularities of full-bodied, token ontic structures. But representing a

category is not equivalent to representing the particularities of category members, and subsumption

under a category is not equivalent to the instantiation of a singular term.

This suggests, minimally, that fulfilling generality and systematicity will require something

different from attaining the kind of “mappings” traditionally cited in (EEM).30 Stated more charitably:

the ontic theorist's notion of “mapping” has thus far been left ambiguous between singular instantiation

and general subsumption. We saw a tidy example of this in Craver & Kaiser's claims, reviewed in §3.2

above. Their account wavered over whether a general explanationC/T/C was intended to “map” to a

number of distinct token mechanisms of the same type, or instead “map” to one superordinate

mechanism that (somehow) produces many token phenomena in many distinct times, places, and

organisms.

Subsumption and denotation are not only logically distinct, they are logically separable. For

example, a “free logic” of the sort advanced by Hintikka (1959) dispenses with the requirement that all

singular terms should refer, but does not deform the notions of predication or generality. This just

shows that the logical relation of subsumption under a category does not presuppose, and is distinct

from, the denotation of singular terms or the instantiation of singular variables. The abstract

possibilities sketched out in such a free logic can be made concrete in numerous ways with attention to

the history of scientific explanation. The phlogiston theory was demonstrably false, but it was, to its

credit, fairly general and systematic. The epistemic norm of generality and systematicity was fulfilled,

but the ontic norms of (EEM) were not. The descriptions, variables, and contents of the phlogiston

theory's explanationsC/T/C did not “map” to traditional explanationsONTIC. Examples could be multiplied.

The coherence of a free logic, along with well-known cases such as phlogiston, suggest that fulfilling

30 See fn.s 17&25.

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the norm of generality and systematicity is logically independent of fulfilling (EEM).

For the same reasons, it would be misguided to suggest that a general and systematic

explanationC/T/C can be understood “extensionally,” as it were – as merely being required to be

“mappable,” however selectively, to any number of the multiple token ontic structures which are

members of the relevant category. In the first place, as phlogiston theory and free logics show, the

purported category-members themselves need not exist, even while scientists offer general/systematic

explanationsC/T/C by purporting to cite these alleged category members. There may be no category

members to “map.” But further, this “extensional” move would conflate the logical distinction between

general subsumption and singular instantiation. True enough, an extensional logic invites confusion on

this point if one is not cautious. A predicate whose extension is one-membered is “extensionally

equivalent” to a singular term that denotes that same object, and a many-membered predicate is

“extensionally equivalent” to a singular variable whose range covers the same cases. Yet these are not,

in a broader sense, logically or truth-functionally equivalent, and no suitable logic would allow the

replacement of predicates with singular terms (or vice versa) to result in a well-formed formula. In a

sense, both expressions have the same scope: yet only one of them is to be regarded as having

generality. Our formal logics correctly enforce a symbolic analogue of this distinction. At best, the

“extensional” move we are considering would dissolve the generality of the explanationC/T/C, reducing it

to mere scope, supporting only the merely conjunctive recognition that the explanationC/T/C applies to

many cases. We would then be right back where we started, facing the normative demand to make such

scope intelligible by specifying a general and systematic principle of extrapolation.

This first line of argument shows that there is no logical reason to require instantiation of

singular terms (“mapping” to traditional explanationsONTIC) as a prerequisite for subsumption under a

category (general and systematic explanationC/T/C).

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4.2: The Material Line of Argument (and the Problem of Universals!?)

My second line of argument focuses on the content of the claims under dispute. First, as stated in §2,

the ontic view takes the following two claims to be definitive of explanationsONTIC,

(C1) An explanationONTIC is what causes, constitutes, or is otherwise responsible for the production of an explanandum phenomenon.

(C2) An explanationONTIC has no normative or intentional properties whatsoever; it just is.

According to (EEM), every fully-successful explanationC/T/C must “map” to such an explanationONTIC. I

claimed in §3.2, and defended in §4.1, that a general and systematic explanationC/T/C has a distinct

logical and explanatory import compared to that of a singular explanationC/T/C which “maps” to a token,

concrete explanationONTIC. If (EEM) is still to be maintained as true, then there must be something

distinctive in the ontic counterparts of general and systematic explanationsC/T/C – some (aspect of an)

explanationONTIC which is not “mapped” in a singular explanationC/T/C, and which fundamentally

underlies the unique explanatory accomplishment of any general and systematic explanationC/T/C. Here

it becomes clear that we are (with some embarrassment) impinging upon classic, muckraking disputes

regarding the problem of universals.31 The problem of universals arises when we ask what, if anything,

could be the ontological counterpart of a representation (mental or otherwise) which has generality and

not mere scope. Only one of the traditional solutions can offer any refuge for the ontic view.

4.2.1: Nominalism & Conceptualism.

The ontic theorist cannot adopt the philosophically least costly options of nominalism or conceptualism

about universals without recognizing the falsity of (EEM). For on either view, fulfilling the norm of

generality and systematicity constitutively involves invoking some explanationTEXT (e.g., a name or

label) or some explanationCOG (e.g., a general concept) which, ex hypothesi, has no correlate in the

mind-independent ontic structure of the world. But that is just to say that attaining generality and

31 I thank Daniel Burnston and Daniel Weiskopf for making clear that this needed to be addressed.

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systematicity requires doing something other than fulfilling (EEM). The ontic theorist who seeks to

uphold (EEM) in general and systematic explanationC/T/C is committed to some form of realism about

universals as the unique ontic correlates which ground the distinction between singular, and general and

systematic, explanationC/T/C .

4.2.2: Platonistic Realism.

A Platonistic account is a poor fit for the ontic view. I presume “having scope,” “having generality” and

“making (or being) intelligible” are not properly ontic determinations at all: they are logico-semantic

determinations that depend upon the existence of intentional agents who think, communicate, and

reason. By (C2), no explanationONTIC (no “full-bodied thing”) can have such determinations – or if it

does, these features are strictly speaking of no explanatoryONTIC import.32 So I presume the ontic theorist

agrees that no Platonistic ontic structures exist, which themselves have generality or make things

intelligible (as it were) to which one could directly “map” a general and systematic explanationC/T/C.

It is unclear how a naturalistically-minded philosopher of scientific practice could endorse such

“occult” entities. One might, of course, look to a token explanationONTIC and state a general hypothesis

(explanationCOMM) or formulate a general model or theory (explanationTEXT) or otherwise generally

represent to oneself (explanationCOG) that this explanationONTIC serves (in some respect) as an exemplar

of a general category. These are perfectly respectable ways for scientists, as intentional agents, to attain

categorical representations, formulate principles of extrapolation, and make scope intelligible.33 But the

central tenet of Platonism is that such generalizing and categorizing practices cannot be understood

simply as “mapping” to full-bodied things in the natural world: they rather “map,” if you will, to non-

spatiotemporal entities called “universals.” And thus a Platonistic universal plausibly violates (C1): it is

32 Nowhere in his (2007) does Craver clearly commit to the claim that mechanistic explanations can account for mental representation, nor that his quarry, explanation in neuroscience (note: not cognitive neuroscience) makes use of this concept. His account is perhaps better read as focused upon “neural syntax” (Buszáki 2010).

33 Modulo the concerns of fn.17.

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difficult to see how non-spatio-temporal entities could be of relevance to the production of an

explanandum phenomenon.

4.2.3: Aristotelian Realism.

Part and parcel of a traditional explanationONTIC is the having of certain properties that are of relevance

for the production of an explanandum phenomenon. A property-instantiation in an explanationONTIC is

not itself general, of course, but it may be said that all that is required for general and systematizing

explanation is that the cases in a model's scope share instantiations of the same property. On such a

view, the “sharing” makes the model's scope intelligible, and so a general explanation should, just as

(EEM) requires, “map to” ontic structures – including to their shared property-instantiations.

Let us be clear about how the view needs to be spelled out to be taken seriously. A classical

Aristotelian view holds that the very same universal is literally co-located in each of its instances, so

that a universal exists in multiple places and times: that is what it means to say that tokens “share” a

property via their respective property-instantiations. Whereas a Platonic universal has no

spatiotemporal location, an Aristotelian universal need have no one spatiotemporal location. So the

ontic theorist cannot just maintain that isolated property-instantiations must be counted as part of the

explanationONTIC in a general and systematic explanationC/T/C – this does not yet invoke the Aristotelian's

posited ontic correlate of generality. The ontic theorist must claim that the explanatory difference

between a singular and a general and systematic explanationC/T/C lies in their distinct “mappings” to,

respectively, property-instances and spatiotemporally-distributed Aristotelian universals.

Craver and Kaiser offer two kind of claims which might be taken to suggest a kind of neo-

Aristotelianism. The first is their (perhaps unintended) claim, first encountered in §3.2 above, that

when a regularity is exhibited, with a common type of phenomenon being produced in a number of

distinct token cases, somehow “an underlying mechanism... explains[ONTIC] them” all (2013., p.134, my

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ital.). Perhaps this odd, spatiotemporally-distributed mechanism is a neo-Aristotelian universal, and our

general and systematizing explanationC/T/C of the regularity should “map” to it.34 As a second,

contrasting, and more plausible option, Craver and Kaiser distinguish “regularities, which are statistical

patterns of dependence and independence among magnitudes, from generalizations, which describe

regularities” (2013, p.128). So perhaps they maintain that we should include “regularities” in our

ontology as explanationsONTIC, and map general and systematic explanationC/T/C to them.35 It would then

be clear how a number of token mechanisms of the same type, operating in distinct times and places,

could underwrite the regularity, literally producing it as a new ontic structure. Without going into the

ontology here, I shall count both views as (neo-)Aristotelian options, in which some spatiotemporally-

distributed explanationONTIC is posited as the ontic correlate of general and systematic explanationsC/T/C.

This “material” line of argument suggests that unless (EEM) is simply to be abandoned as false,

an Aristotelian conception of universals offers the ontic theorist the sole option for positing

explanationsONTIC to which general and systematizing explanations can be said to “map.” At first glance

this appears, at least in principle, a defensible position for the ontic view. I now argue otherwise.

4.3: The Practical Line of Argument

In a deep sense, the ontic theorist who pursues Aristotelianism has likely already given up the game.

34 I am quite certain this is not Craver's intended view, but I flag it to emphasize how this way of talking hides the whole problem of generality and systematicity, and the whole problem of making scope intelligible. The explicit example givenhere, which may be only a slip of the pen, sensitizes us to less obtrusive cases. For example, throughout his (2007), Craver is constantly discussing such things as “the mechanism of the action potential.” Which one? Much of the text has in focus particular instances of a mechanism which is producing a token action potential as token phenomenon (see e.g., ch.1). When we get to the mosaic unity of neuroscience, however, there is recourse to an “abstract mechanism” of e.g., long-term potentiation (ibid., p.228) which can be shared as an explanatory target by multiple practitioners, working in multiple fields, in multiple times and places, studying multiple token cells, organisms, etc. And yet in Craver's favored descriptions, he hides any abstractness, saying for example that all the fields are involved in providing “independent constraints on a common multilevel mechanism” (ibid., p.232). Which one? It is not as if neuroscientists, psychologists, computer scientists, etc., are all huddled around a single neuron firing an action potential, or a single hippocampal slice exhibiting LTP. Or again, Craver says that findings from different fields “provide different constraints on the same mechanism... expose different aspects of a single mechanism” (ibid., p.240); “The mosaic unity of neuroscience results from the integration of constraints from multiple fields on a common mechanism” (ibid., p.248). The claim which is clearly intended throughout concerns a shared conception of a type of mechanism – which is no mechanism.

35 I thank Trey Boone for pressing me to address this point.

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For what incurs ontological commitment to the relevant Aristotelian universals is plausibly the prior

recognition that we have in place explanatoryC/T/C practices that attain generality and systematicity.

Aristotelian universals – including “regularities” or “patterns” – are posited (by some) on these

grounds. If any practice-oriented philosopher of science winds up committed to realism about the

relevant universals, it will be an a posteriori realism (Armstrong 1983). On such a view, our prior

epistemic success in providing general and systematizing explanationsC/T/C is our grounds for positing

universals (and regularities) as their correlate explanationsONTIC. Once such explanationsONTIC are

posited, of course, they are posited as real, and so one who posits them is inclined to say that they were

there all along, and that the success of the explanationsC/T/C must have been partly constituted by

fulfilling ontic norms. But positing Aristotelian universals contributes nothing to the actual practice of

good scientific explanation (or to practice-oriented philosophy of science). The Aristotelian defense of

the ontic view depends upon invoking a (contentious) philosophical norm of speculative ontology,

rather than having any basis in the norms which govern scientific explanationC/T/C in practice.36

As we have seen in §3.2 above, Craver & Kaiser themselves don't (and can't plausibly) resist

admitting that to make intelligible any regularity, and to make intelligible the scope of any model, we

must appeal to general and systematic explanationsCOG. Indeed, despite their initial modulation of

Bechtel & Abrahamen's view, they implicitly admit that to say that a regularity obtains as such – not

simply that a number of singular events occur – one must say that each instance of the regularity is

“produced or maintained by a mechanism” which is “more or less similar” to an exemplar (2013,

p.134). This is precisely a presupposition of (non-classical) general and systematic explanationC/T/C in

formulating claims about regularities: a “regularity” is said to obtain because one thinks that

mechanisms of the same type typically produce phenomena of the same type. One is free to reify the

36 The argument could be extended against any plausible, a posteriori realism about any Platonistic explanationsONTIC which one might posit in (the philosophy of the metaphysics of) natural science.

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regularity, and the “types,” if one wishes. But in doing so, the resulting conception of the world is

shown to be beholden to a prior grip on our epistemic practices – we have constructed this conception

of the world to accommodate our best epistemic practices.

This undermines the alleged normative priority of ontic norms. On an Aristotelian view, the

ontic theorist can indeed insist that there is no form of explanationC/T/C which does not require

“mapping” to explanationsONTIC . But this is a Pyrrhic victory: they have simply brought on board

additional ontological commitments which are only motivated by a hypothesis that the world must be

regarded as cohesive with our best explanatoryC/T/C practices. One cannot then turn around and suggest

in good faith that the very same ontological posits have priority in imposing unidirectional constraints

upon our epistemic practices. If there is an “asymmetric direction of fit” here, then contra Craver

(2014, p.36), it is ontological posits which are constrained to fit with epistemic practices, not the other

way around. That is to say, there is a form of success in explanationC/T/C which does not require

fulfilling (EEM) in any substantive sense, since one can at best posit that (EEM) has been fulfilled in

light of our prior explanatoryC/T/C success. Thus (EEM) emerges as at best a vacuous constraint when

applied to general and systematic explanationsC/T/C, and the normative priority of ontic norms emerges

as indefensible in this case. Epistemic norms have priority in attaining generality and systematicity.

5: Further Objections and Application to Strevens

The arguments I have raised against (EEM) are so damning that one might suspect me of begging the

question, or suspect that my argument trades on idiosyncrasies of Craver's view. In this section I first

(§5.1) defend against the suggestion that I have begged the question, and I elaborate the positive upshot

of my view by contrasting my claims with Illari's. I then (§5.2) show that Strevens' alternative ontic

view faces all the same problems I have raised for Craver, thereby generalizing my argument.

5.1: Further Objections

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One way in which I may be accused of begging the question is by claiming that (e.g., in the case of

phlogiston) it is possible to have a general and systematizing explanationC/T/C which nonetheless

invokes no corresponding token explanationsONTIC. Surely this begs the question against the ontic view,

no? No. After the semantic ascent, the ontic theorist cannot begrudge me an epistemic sense of “general

and systematizing explanation” which does not mean the same as explanationONTIC. If we take the

normative turn, the true task for the ontic theorist who promotes (EEM) is to make good on its

conjecture of the normative priority of ontic norms, showing that, whatever we mean by

“explanationC/T/C,” its full success must constitutively involve “mappability” to explanationsONTIC. I

argued (§4.1) that the ontic theorist cannot readily make good on this conjecture, since fulfilling the

norm of generality and systematicity requires attaining an explanationC/T/C which cannot plausibly be

understood as requiring “mappability” to any traditional explanationsONTIC. The foray into the problem

of universals (§4.2.2) suggested that an alternative conception of explanationsONTIC could at best uphold

(EEM) by positing novel explanationsONTIC such as Aristotelian universals. But this is a moot victory,

since licensing such posits plausibly presupposes prior success in attaining general and systematic

explanationC/T/C (§4.3). This argument defeats (EEM) on its own terms.

There is another way I might be accused of begging the question. Craver has argued that any

view which holds that “explanations explain by subsuming a phenomenon under a general

representation” is “too weak to serve as a guide to the norms that distinguish good explanations from

bad and complete explanations from incomplete” (2007, p.28). This is a key argument in favor of his

ontic view (ibid., ch.2). But the major complaint Craver raises against classic appeals to generality and

systematicity (the DN account, unificationist account, and others – cf. Craver 2007, pp.28-49) is that

such views fail to impose various norms of explanation which he deems decisive. According to Craver,

a view of explanation which prioritizes subsumption cannot support the following claims:

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“(E1) mere temporal sequences are not explanatory (temporal sequences);(E2) causes explain effects and not vice versa (asymmetry);(E3) causally independent effects of common causes do not explain one another

(common cause);(E4) causally irrelevant phenomena are not explanatory (relevance); and(E5) causes need not make effects probably to explain them (improbable effects)”

(ibid., p.26).

Each of these would appear to be plausible clarifications of the ontic norms of (EEM), and an

elaboration of the kinds of explanationONTIC to which explanationC/T/C are (in Craver's view) required to

map. As Craver himself notes, (E1-E5) are precisely the claims that Salmon employs to articulate the

ontic view (ibid., pp.26-27). It is on these grounds, I think, that Illari rightly suggests that earlier

attempts to argue in favor of a non-reconciliatory ontic view by demanding support for (E1-E5) simply

begged the question against an epistemic view (Illari, 2013, p.5).

Now I am not attempting (here) to reject ontic norms, or to make them always subservient to

epistemic norms. Rather I have argued that attaining generality and systematicity is an autonomous

epistemic norm of explanation (which Craver himself does and ought to recognize – §§3.2&3.3 above)

which cannot be fulfilled in simple conjunction with traditional ontic norms. It is perfectly compatible

to grant that (EEM) sometimes succeeds in delineating a similarly autonomous ontic norm that cannot

be fulfilled by providing a general and systematic explanation. Where an isolated event is only

susceptible to singular explanation, that explanation will have no scope, and will not raise the issues of

intelligibility which generality and systematicity is required to resolve. Like the appeal to (E1-E5), this

point has served as a common argument in favor of the ontic view. Following Bogen (2005), Craver &

Kaiser promote an ontic view on the grounds that “the causal structure of [a] mechanism is something

over and above the regularities by which that structure can be detected” (2013, p.138), such that

identifying an explanationONTIC in a singular explanationC/T/C need not constitutively involve attaining a

general and systematic explanationC/T/C.

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I grant this much: for some irregular phenomena, there may be no possibility of general and

systematic explanation, and singular explanation in accordance with (EEM) may fulfill all relevant

norms. This would not in any way diminish normative demands to attain generality and systematicity

where we can, and in ways (EEM) cannot support. In this way, I do not beg the question against the

ontic theorist, since I allow that some explanationsC/T/C should fulfill (EEM) as a substantive constraint.

I only insist that other explanationsC/T/C should attain generality and systematicity, and that doing so

cannot be understood in terms of the normative priority of ontic norms. To invert Craver & Kaiser's

conclusion: general and systematic explanationC/T/C are something over and above singular

explanationC/T/C . Scientists seek both, but thereby pursue very different aims.

In saying this, I am in a way rejecting Craver's suggestion that an appeal to subsumption is “too

weak to serve as a guide to the norms that distinguish good explanations from bad and complete

explanations from incomplete” (2007, p.28). I reject it because the issue is not one of strength. The

normative demands of (EEM) are as strong as one likes, where they apply, and the normative demands

of generality and systematicity are just as strong where they apply. For all my arguments show, Craver

is quite right that norms of generality and systematicity do not themselves direct us to fulfill (EEM).

But if my arguments are correct, it is equally true that the normative demands of (EEM), where

substantive, do not themselves direct us to us to attain generality and systematicity. The upshot is that

Craver's arguments against an epistemic view are not only question-begging, they are self-defeating:

Craver needs an account of norms of generality and systematicity, and his own ontic view cannot

plausibly underwrite it. The sensible conclusion is to regard the two sets of norms as autonomous of

each other, and to deny (EEM)'s global claim of normative priority. We simply cannot fulfill all the

norms which make for good explanations at once. If we recognize normative autonomy in this way, we

should abandon the view that any one form of explanation can be examined to provide a complete

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account of what makes an explanation good or bad. We should abandon the reconciliatory ontic view.

Here I also disagree with Illari, if she in fact endorses the normative priority of ontic norms by

suggesting that we must fulfill ontic and epistemic norms in tandem, or simultaneously (see again §2.2

above). I am not denying that fulfillment of both epistemic and ontic norms is a regulative ideal in

explanatory practice. If we recognize the normative autonomy of some (any) ontic and epistemic

norms, we must grant that fulfilling them requires a kind of dynamical and temporally extended zig-zag

between distinct explanatory practices. What I have called “heuristic category theory” (§3.2 above)

embodies such an account of a dynamical practice that reconciles the ontic and epistemic norms I have

been discussing. As explanationsC/T/C are developed for token cases and de facto extrapolated, attaining

scope, we devise fallible general and systematic explanationsC/T/C to make that scope intelligible;

alternatively, we formulate a presumptive category to guide prospective extrapolation, and check token

cases to see if our general and systematic explanationsC/T/C are enabling us to extrapolate models in a

way that “gets things right” in their applications. We are so adept at generalizing that we are apt to

overlook the logically distinct (§4.1) phases of such practices. It may be that Illari anticipates

something like this view when she later writes that to successfully disentangle epistemic and ontic

norms, we will “need to look at what is happening over time, rather than at a single time” (ibid., p.18).

What I have done is to clarify the temporal interplay between epistemic and ontic success.

So I maintain that I have not begged the question against Craver's ontic view. As I discuss in the

next subsection, my arguments also apply to ontic views aside from Craver's.

5.1: Strevens' Kairetic Account

Strevens initially situates his “kairetic” account of explanation within what he calls the “causal

tradition,” maintaining that “explaining a phenomenon is... a matter of understanding how the

phenomenon was or is causally produced” (2008, p.3). Strevens' is a “two-factor” account,” which

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grants that we need an account of a “selection principle” which will allow us to “extract from the

[causal] network the particular causal facts that are relevant to understanding the phenomenon” (ibid.,

p.3). This is a commitment to both ontic and epistemic norms, broadly construed, with priority given to

getting some things right (i.e., whichever things are relevant).37 Unlike Craver's focus on mechanisms

as explanationsONTIC, Strevens initially appeals to a broader class of difference-makers as “the parts of

the causal network that are explanatory relevant” for any explanandum phenomenon (2004, p.158).

Strevens later seeks to accommodate non-causal explanationsONTIC in the kairetic account (2008,

§5.7). He countenances difference-makers which are not causes, saying that “while the causal influence

relation is one kind of raw metaphysical dependence relation that can serve as the basis of the

difference-making relation, there are others as well... any of the difference-making relations so based is

explanatory” (ibid., pp177; 178-9). So not all explanationsONTIC (difference-makers) are causal.38

Nonetheless, Strevens remains committed to the normative priority of ontic norms. He has made this

clear in a recent article, saying: “the norms of correct scientific understanding logically precede and

participate in determining the nature and norms of understanding” (2013, p.510).39

When stating (EEM), I removed (3M)'s focus on mechanisms and on causal dependencies to

permit other kinds of explanationONTIC, and so (EEM) covers Strevens' more expansive view. As far as

my argument is concerned, what matters is whether Strevens has some way of dealing with general and

systematic explanationsC/T/C which can preserve the normative priority of ontic norms. It is worth

stressing that the kairetic account was not intended to incorporate or address generality in the sense at

issue. The kairetic account was constructed to overcome problems for earlier ontic accounts, arising

37 That Strevens is committed to normative priority is also borne out by a slogan he offered at a symposium for the recent 2014 meeting of the Philosophy of Science Association: “Ontic first, but not only.”

38 Note that Strevens is noncommittal regarding whether mathematical explanationsONTIC are part of his account of scientific explanation (cf. 2008, pp.329ff). These, I suppose, could be known a priori – but their use in scientific explanation clearly involves a posteriori knowledge of causal regularities, in his view.

39 Strevens does discuss the possibility of “accuracy/generality trade-offs” (2008, §5.2). But he does not clearly advocate for them, and further (see below) he does not understand “generality” in the sense at issue.

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from idealized explanationsC/T/C “in which causal details are either omitted or distorted” (2004, p.156).

Strevens suggests that a view which prioritizes general and systematic explanationsC/T/C (e.g.,

unificationism) can somehow deal with idealization by saying that “a kind of generality... may be well

enhanced by omitting or changing the details,” whereas the difficulty is that the ontic view “imposes no

generality desideratum to counterbalance the drive for causal accuracy” (ibid., p.157). Again:

“...the kairetic account is not a hybrid account of explanation, but a fully causal account:the technical apparatus of the unification approach is appropriated not for its ability tocapture the notion of unification, but rather, for its ability – quite unintended by itscreators – to capture a notion crucial to the causal account, namely, the notion ofdifference-making” (2004, p.154).

If the kairetic account seeks not to invoke a norm of generality and systematicity, it is unlikely to offer

resources for upholding (EEM) in general and systematic explanationC/T/C.

I flag this in advance since Strevens' remarks leave it quite unclear whether he recognizes that

there is a norm of attaining generality and systematicity in the sense at issue. This is in part betrayed by

the odd connection he draws between idealization and “generality” above. As noted in §4.1 above, the

issue of idealization does not get to the core of generality in the sense I am concerned with. That is

because none of (i) the instantiation of singular terms (however many), and likewise (ii) the omission of

singular terms and (iii) the assignment of inaccurate denotations for singular terms (both of which

latter can occur in an idealizing explanationC/T/C) – none of these, I say, has anything constitutively to do

with (iv) the subsumption of members under a category. The problem of generality and systematicity

arises for the ontic view because (EEM) requires mapping to “details.” The number of the details, and

the degree of their detailedness, are not at issue. The issue is how to square generality and systematicity

with the traditional requirement of “mapping” to any details. Generality, as I employ the term, is not

equivalent with (ii) above – what Strevens calls “elimination” – or with (iii) above – what Strevens

calls “abstraction” (ibid., pp.96-7). All of (i-iii) concern mere scope, not generality.

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Strevens himself does not distinguish these issues. The core of the kairetic account is to suggest

that a particularistic model M (explanationC/T/C) can be “optimized” by the omission of detail to attain

an “explanatory kernel,” which is the “most abstract veridical causal model that entails the

explanandum” (2004, p.169) or “the maximal abstraction of M that causally entails” the explanandum

(2008, p.97). As a measure of the “abstractness” of an explanationC/T/C, Strevens once offered the claim

that “abstractness is proportional to the standard measure (in the mathematical sense) of the set of

possible physical systems [i.e., explanationsONTIC] satisfying the model” (2004., p.169). This is clearly a

measure of the explanation'sC/T/C scope, the number of cases to which can apply. This is just where the

normative demand for generality and systematicity will kick in, requiring us to specify a principle of

extrapolation which makes the explanation'sC/T/C scope (or, “abstractness-measure”) intelligible.

Strevens offers nothing of substance on this front. He sometimes admits that his measure of

abstractness is “similar, though not identical to” (ibid., p.170) or “subtly different from” (2008, p.110)

any measure of generality. The difference is not so subtle: although one-membered categories and

singular terms, or many-membered categories and singular variables, might be regarded as

extensionally equivalent, they ought not to be regarded as logically equivalent in any important sense

(see §4.1 above), and no measure of one should be confused for a measure of the other. Strevens treats

them interchangeably, saying that an explanatory kernel is “as general as possible” once we have

completed its optimization (2004., p.170). Generality, in the sense at issue, cannot emerge from a

particularistic model stripped of details. Eliminate as many singular terms as you like, and extend the

scope of singular variables as much as you like: you do not obtain something logically equivalent to

quantification or predication. Strevens does not mark the distinction, saying that the kairetic account

requires that an explanatory kernel K meet a desideratum of“Generality: K is satisfied by as many

physically possible systems as can be” (ibid., p.172), alternatively stated as: “K is abstract as it can be

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(generality)” (2008, p.110). But this is mere scope. Generality, in the sense at issue, is not meaningfully

countenanced in any systematic way by Strevens. (Of course, he is permitted to use the term

“generality” in this way, but it is of no help in addressing the point at issue).

Where issues of generality are clearly in play, Strevens lands himself in the problems I have

raised as clearly as one could. Strevens adopts a causal-mechanical account of causal generalizations –

all of which he permissively counts as “laws.” An example of such a law is:

“The apple law: If at time t, an apple falls from a tree on the surface of a planet with mass

M and radius r, it will hit the ground at time t + r √2d /GM , where d is the distancebetween the apple and the ground and G is the gravitational constant” (ibid., p.222).

I set aside a Strevens' elaborate “ceteris paribus” (ibid., p.222-3). Now the causal-mechanical view

which Strevens endorses is that “in order to explain[C/T/C] the apple law, you must describe the causal

mechanism [i.e., explanationONTIC] – more specifically, the gravitational mechanism – in virtue of which

any apple detached from its tree under the assumed circumstances falls in the stated time” (ibid.,

p.223). This seems confused: how could an explanation of a token case (however many) serve as an

explanation of such a generalization? Yet Strevens codifies it as “the following tenet of the causal-

mechanical approach to regularity explanation:

First Fundamental Theorem of Explanation: The explanation of a causal generalization and the explanation of any instance of the generalization invoke the same causal mechanism” (ibid., p. 223).

This “fundamental theorem” is simply the bald assertion that something like (EEM) can account for

general and systematizing explanation, absent any recognition that the (EEM) must incur commitment

to novel explanationsONTIC to underwrite the distinct explanatory power of generalizing and

systematizing explanations versus singular explanations. This is akin to failing to distinguish property-

instances from spatiotemporally-distributed, Aristotelian universals (§4.2.3 above). By asserting this

theorem as fundamental, Strevens refuses to offer any suitable account. For all the reasons put forth in

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§4, I cannot see that there could be any suitable account: ontic accounts of explanation which support

(EEM) cannot support norms of generality and systematicity. For reasons clarified in §§3.2&3.3, this

seems a decisive objection against (EEM), since it prevents any intelligible account of a model's scope,

and thereby any account of common scientific practices of prospective extrapolation.40

6: Conclusion.

I introduced the ontic view (§2), clarified the norm of generality and systematicity (§3), then argued

that this norm could not be countenanced while upholding the normative priority of ontic norms (§4). I

finally defended against objections that my argument was question-begging or idiosyncratic to Craver

(§5). No extant account of ontic explanation can support norms of generality and systematicity, and this

is because in general and systematic explanations, fulfilling epistemic norms takes priority, which is in

direct conflict with the basic spirit of the ontic view.

At present the epistemic-ontic debate is best viewed, I have suggested, as a dispute over the

normative priority and normative autonomy of both ontic and epistemic norms. In the future, it seems

likely that philosophy of explanation will need to generate more nuanced conceptions of constraining

and exclusionary relations between norms, owing to the fact that no simple, conjunctive reconciliation

of the epistemic and ontic views looks to be forthcoming. (Here I recommend Weisberg's (2013)

treatment of the norms of modeling practice as exemplary.) At present, the best chance at reconciling

the epistemic and ontic views it to admit that epistemic norms sometimes have priority (e.g., in cases of

general and systematizing explanation) and that ontic norms may sometimes have priority (e.g., in

cases of singular explanation). Attaining both varieties of explanation requires a dynamic practice of

moving back and forth between distinct explanatory practices. This is not, strictly speaking, a trade-off,

since we need not entirely forego one form of explanation to attain the other. Likewise these

40 For a Strevens' presupposition of a general and systematic explanationCOG in claiming that regularities obtain, see his claims on “basing generalizations” (2008 p.228ff).

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explanatory practices are not, strictly speaking, incompatible in the long run. But we should not hold

out hope for an analysis of a unitary and ideally-good explanatory practice, in the singular; rather we

must recognize a multiplicity and interplay of norms governing multiple explanatory practices.

In closing, I note that my argument and van Eck's (2015) against the reconciliatory ontic view

complement each other. van Eck first clarifies epistemic norms which in his view are presupposed in

positing any singular mechanism as an explanationONTIC. I have not addressed this point, though I find

van Eck's claims rather compelling, and they suggest a generalization of the line of thought pursued

here: why shouldn't a practice-oriented philosopher of science endorse an a posteriori realism about the

vast majority of the explanationsONTIC which they or scientists care to posit, not just universals, and why

shouldn't this lead to a rather more global normative priority of epistemic norms? Once one posits ontic

structures, of course, they are posited as real, and so one is inclined to say they were there all along,

and that they will continue to be there, imposing ontic constraints. But isn't positing, after all, an

epistemic activity, and aren't norms of good positing presupposed in setting out any ontic norm?

Meanwhile, my claims support van Eck's further argument regarding cases where scientists offer a

mechanistic explanation of a now-extinct mechanism. Crucial to his argument is that scientists rely on

commonalities between extant mechanisms to infer the properties of past mechanisms. He not

implausibly points out that this will involve the presupposition of general categories so as to intelligibly

extrapolate from models of current mechanisms to past cases, thereby prioritizing epistemic norms

(ibid., p.20). My claims clarify in detail why van Eck's argument has teeth against (EEM). The ontic

theorist cannot simply respond to van Eck by expanding their ontology, supposing that past

mechanisms do still exist (e.g., as in a growing block theory of time). The key issue is making scope

and extrapolation intelligible in scientific practice, not any philosophical niceties regarding one's

preferred ontology of the past.

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