2007. Dispositions and Essences

Chapter 3

Dispositions and Essences

Claudine Tiercelin

From some time now, dispositions have no longer been viewed as ethereal or occult powers that have a pre-scientific status, threats or ghostly forces in need of redemption, mere promissory notes, some lazy or inaccurate way of talking that no self-respecting scientist should ever use.1 The pregnant spinsters have now acquired the respectable status of unmarried mothers, up to the point that they do lead a life of their own. Indeed, not only are they viewed as possible accidental properties of things: they are taken as essential properties of things in nature. Even more, for some philosophers, all things in nature are essentially dispositional. I have tried elsewhere2 to sketch the historical and philosophical reasons why there might have been such a revolution from pure elimination (as may be found under various forms in Boyle,3 Quine,4 Goodman,5 or Ryle6) to inflation (Ian Thompson,7 Rom Harré8, Nancy Cartwright9, Karl Popper10, Hugh Mellor11, Simon Blackburn12) as regards dispositions, powers or capacities (with, in some cases,

1 As D.H. Mellor already observed, some thirty years ago, in his famous ‘In Defense

of Dispositions’, Philosophical Review, 83 (1974): 157-181. 2 ‘Sur la réalité des propriétés dispositionnelles’, Actes du Colloque de l’université de

Caen (janvier-février 2000), Cahiers de Philosophie de l’Université de Caen, n°38-39 (2002): 127-157.

3 R. Boyle, ‘The Origins and Forms of Qualities’, in M.A. Stewart (ed.), Selected Philosophical Papers of Robert Boyle (Indianapolis, 1991), pp. 1-96.

4 Cf. for ex. W.V. Quine, The Roots of Reference (La Salle, Ill., 1974), p. 11, or The Ways of Paradox (New York, 1966), pp. 71-72.

5 N. Goodman, Fact, Fiction and Forecast (Indianapolis, 1955). 6 G. Ryle, The Concept of Mind (London, 1949). 7 I.J. Thompson, ‘Real Dispositions in the Physical World’, British Journal for the

Philosophy of Science, 39 (1988): 67-79, pp. 76-77. 8 R. Harré, ‘Powers’, British Journal for the Philosophy of Science, 2 (1970): 55-101;

R. Harré and E.H. Madden, ‘Natural Powers and Powerful Natures’, Philosophy 48 (1973): 209-230; R. Harré and E.H. Madden, Causal Powers: A Theory of Natural Necessity (Oxford, 1975).

9 N. Cartwright, Nature’s Capacities and their Measurement (Oxford, 1989): ‘It is not the laws that are fundamental, but rather the capacities’, p. 181; also see The Dappled World (Cambridge, 1999).

Dispositions and Essences 89

their idealistic consequences13). In what follows, I would like to concentrate on some less extreme versions of dispositional essentialism such as have been proposed by some authors, especially Brian Ellis, and in an even less extreme version, I think, by Stephen Mumford. I shall begin by presenting Ellis’s main lines of argument and then try to see whether some of the difficulties raised by his account and the answers suggested by Mumford are satisfactory, especially as far as a dispositionalist account of laws is concerned. Favoring myself some form of dispositional realism14 rather than essentialism, I shall finally less present here some arguments in favor of such a position than merely make some suggestions as to what seem to me the major difficulties which any kind of dispositionalism should be ready to face. Brian Ellis’s Conception of Dispositional Essentialism: the Main Arguments15 Ellis’s conception of dispositional essentialism (which he first exposed in an article written with Caroline Lierse in 1994) is part and parcel of the more general view he now entitles scientific essentialism, which can be summarized in three basic theses:16 1) Scientific essentialism deals with natural kinds such as events and processes and not only with objects and substances. According to Ellis, ‘the world is structured into hierarchies of natural kinds of objects and processes: it is not an amorphous world on which we must somehow impose our own system of categories. There is a pre-existing grid of objective categories, and it is the aim of

10 K. Popper, A World of Propensities (Bristol, 1990). 11 D.H. Mellor, especially ‘In Defense of Dispositions’; ‘Counting Corners Correctly’,

Analysis, 42 (1974): 96-97 and ‘The Semantics and Ontology of Dispositions’, Mind, vol. 109, 436 (2000): 757-779.

12 For S. Blackburn, science finds dispositions ‘all the way down’, ‘Filling in Space’, Analysis, 50 (1990): 62-65.

13 Cf. S. Blackburn, Ibid. 14 I have tried to spell out some arguments in favor of such a position in ‘Sur la réalité

des propriétés dispositionnelles’. The scientific Image of Mankind’ (NESIM). 15 B.D. Ellis and C.E. Lierse, ‘Dispositional Essentialism’, Australasian Journal of

Philosophy, 72 (1994): 27-45; ‘Natural Kinds and Natural Kind Reasoning’, in P. Riggs (ed.), Natural Kinds, Laws of Nature and Scientific methodology (Dordrecht, 1996), pp. 11-28; ‘Causal Powers and the Laws of Nature’, in H. Sankey (ed.), Causation and Laws of Nature (Dordrecht, 1999), pp. 21-42; ‘Bigelow’s Worries about Scientific Essentialism’, pp. 77-97; ‘Response to D. Armstrong’, pp. 49-55; Scientific Essentialism (Cambridge, 2001); and for a good summary of his position, see ‘The New Essentialism and the Scientific Image of Mankind (NESIM) http://www.rescogitans.it/ita/scenari/tilgher/Ellis.htm.

16 Cf. NESIM, 3 ‘Scientific essentialism’.

90 Claudine Tiercelin

natural science to reveal and describe them’.17 Scientific essentialism is concerned with natural kinds which range over events and processes as well as with the more traditional sorts which range only over objects or substances.18 The most general laws of nature describe the essential properties of all these global kinds,19 and therefore hold necessarily of all objects, events and processes: ‘The law of conservation of energy, for example, states that every event or process of this global kind is one that is intrinsically conservative of energy. Hence, any event which was not intrinsically conservative of energy could not be one of a kind that would occur in our world. The laws we think of as causal laws are generally more specific in their direct application. The laws of electromagnetism, for example, apply directly to all electromagnetic radiation, and hold necessarily of all such radiation. Therefore, if there is any radiation which is not propagated according to these laws, it cannot possibly be electromagnetic’.20 2) Secondly, scientific essentialism claims that ‘the essential properties of the most fundamental kinds of things are not just the passive primary qualities of classical mechanism, but also include a number of causal powers, capacities and propensities – powers to act, and powers to interact’ 21, namely properties which are essentially dispositional in nature, implying dispositions to act and react in various ways, depending on the circumstances. Traditionally, such properties have been thought to be ontologically dependent on underlying categorical (i.e. non dispositional) properties and on the laws of nature. According to the new essentialism, however, at least some of these dispositional properties are fundamental, and not dependent upon any other properties. In other words (one will note the Aristotelian and/or Leibnizian flavor), the basic things in the world are essentially active and dynamic. ‘They are not just passive objects obeying

17 NESIM, 3. 18 Ibid. and Ellis, Scientific Essentialism, p. 3. 19 For Ellis this means that the natural kinds in theses two categories occur in natural

hierarchies. ‘The most general kind in the category of substances includes every other natural kind of substance existing in the world. This is the global kind, for our world, in the category of substances. It defines the range of natural kinds of objects or substances that can exist in our world. The most general kind in the category of events is the global kind, which includes every other natural kind of event or process which occurs in the world. This global kind effectively defines the range of kinds of events or processes that can occur in our world’. B. Ellis, Scientific Essentialism, p. 3.

20 NESIM, 3 and B. Ellis, Scientific Essentialism, p. 6. 21 NESIM, 3 and B. Ellis, Scientific Essentialism, pp. 106-144. This is what D.

Armstrong objects to. See his ‘Reply to Ellis’, in Causation and Laws of Nature, pp. 43-48. He argues that such intrinsic causal powers are Meinongian properties, and thus objectionable. In principle, he says, there could be causal powers which happen never to be exercised. If such properties have no categorical bases, as Ellis allows is possible, then such powers can be defined only by relationships between non-existent objects, i.e. between the kind of circumstances which would trigger them and the kind of display which would then result. For Ellis’s answer see Scientific Essentialism, pp. 133-135.


blindly the commands of God, as most seventeenth and eighteenth Century philosophers believed, a world of things having only the attributes of extension and impenetrability, as Descartes’s and Locke’s worlds were; rather it is a world in which things have their own internal dynamics, which are essential to their natures, and which are determinative of their behaviour’.22 In that respect, ‘all things are essentially active and reactive: at the most basic level, what they are intrinsically disposed to do is what makes them the kinds of things they are. Things of given kinds must always be disposed to behave in certain kinds of ways, just by virtue of being things of these kinds. Their identities as members of these kinds depend on their being so disposed to act’.23 Hence, ‘the real defining characteristics of the most fundamental kinds of things that we know about, namely, thing like protons and electrons, would all appear to lie in their laws of interaction. Things of these kinds would appear to have no real defining characteristics at all apart from their causal roles. A proton, for example, might be defined (by way of real definition) as any particle which behaves as protons do. For no proton could possibly fail to behave in these ways, and no particle other than a proton could possibly imitate this behaviour. Its identity, qua proton, might thus be defined by its causal role. Similarly, one might say that an electron is, by real definition, any particle for which the laws of interaction are precisely those of electrons. Nothing other than an electron could possibly behave in such a way, and whatever does behave in this way has to be an electron’.24 3) Hence a third thesis: the laws concerning the behaviour of protons, and their interactions cannot be just accidental, i.e. laws which could well have been otherwise. On the contrary, it is essential to the nature of the proton that it is disposed to interact with things of various kinds precisely as it does. The protons’s causal powers, capacities and propensities are not just amongst the accidental properties of protons, which depend on what the laws of nature happen to be, but amongst their essential properties, without which there would be no protons, and which protons could not lose without ceasing to exist.25 Accordingly, ‘the traditional view that the laws of particle physics are imposed on intrinsically passive things which have kind identities which are independent of the laws of their behaviour is thus implausible from the point of view of modern science. Essentialism is a much more plausible position to take’.26 As Brian Ellis observes, the claim that the world is structured into hierarchies of natural kinds of objects and so on, could in principle be accepted by philosophers who were otherwise sympathetic to mechanism27: things of different natural kinds,

22 NESIM, 3. Ellis claims that it is this second tenet of scientific essentialism which

sets it apart most strongly from other theories of the nature of reality. 23 Ibid. 24 NESIM, 4. 25 B. Ellis, Scientific Essentialism, p. 2. 26 NESIM, 4. 27 B. Ellis, Scientific Essentialism, p. 107 ff.


they might say, are just things made up of different basic ingredients, or of the same ingredients, but put together in different ways, although there is nothing in their natures which requires that they should behave in one way rather than another. How they are disposed to behave depends on what the laws of nature happen to be. Now it is precisely such a contingency thesis or Humean view of the laws of nature that Ellis denies.28 First, the relationship of dependence between the causal powers and the laws of nature is the other way round: the laws depend on the properties, not the properties on the laws; second implication: the laws of nature are metaphysically necessary and hence true in all possible worlds.29 That is, ‘it must be metaphysically impossible for things, constituted as they are, to behave other than in accordance with the laws of nature. Even God (assuming Him to exist and be all powerful) couldn’t make them behave contrary to their natures. He might change their natures, perhaps, so that they might become, or be replaced by, different kinds of things. But there is no possible world in which things, constituted as they are, could behave any differently. For them to behave differently, they would have to be or become things of different kinds, or be made up of things of different kinds’.30 Hence laws of nature are both descriptive and prescriptive: ‘What science observes and codifies are the manifestations of these dispositions. Hence, laws which describe how dispositional properties act will, at the same time, tell us what things which have these properties essentially must do in virtue of being the kinds of things they are’.31 The natural dispositions are the truthmakers for these laws. Mumford’s Dispositional Essentialism Even if Mumford characterizes his own position as being mainly a functionalist32 view of dispositions coupled with a neutral monistic ontology, at several places,

28 Ibid., p. 4, p. 7, and p. 44 ff, p. 211 ff., p. 229 ff., p. 261 ff. 29 Ibid., part four, chs 6 and 7, p. 203 ff. 30 ‘The most elementary kinds of things all have fixed causal powers, i.e. their

dispositional properties are all fixed by their essential natures. A copper atom, for example, has the same dispositional properties wherever or whenever it might occur. The same is true of a proton or an electron. They are things which belong to what might be termed “fixed natural kinds”. Their distinguishing feature is that you cannot change any of their dispositional properties. They do what things of these kinds always do, and you cannot teach them any new tricks. There can be no question of a copper atom, for example, being disposed to behave in one way at one time, but in a different way at another time. Nothing with such variable powers could possibly be a copper atom’. NESIM, 5.

31 B. Ellis and C. Lierse, ‘Dispositional Essentialism’, p. 40. 32 I have shown in ‘Sur la réalité des propriétés dispositionnelles’, the difficulties

raised by a ‘functionalist’ account of dispositions. On the problems linked with ‘functions’, see also J. Searle, The Construction of Social Reality (New York, 1995), p. 29 ff.


especially in his comment on Ellis & Lierse’s paper33 as well as in the last chapter of his book Dispositions,34 he admits that he endorses dispositional essentialism for certain basic kinds and agrees with many points raised by Ellis and Lierse: only, he takes them to task for the ontology they deem necessary for their position. So, let me try to spell out what are the main arguments Mumford advances in favor of such a dispositional essentialism: 1. First of all, Mumford thinks that ‘the explanatory value of appeal to dispositions typically resides in them being causally efficacious and being properties’.35 It means that they cannot be reduced, for example, to a different class of entities such as events or occurrences, and that their criterion of existence is the causal criterion which can be defined in the following way: ‘The causal criterion of property existence: for any intrinsic abstract property P, P exists if and only if there are circumstances C in which the instantiations of P have causal consequences’.36 2. Ellis and Lierse, at least in their 1994 paper, were very clear that they did not seek to ‘restore the reputation of dispositions by attacking the status of categorical properties, or by arguing that all properties are basically dispositional, as some philosophers have done’37, but mainly to show that ‘their lowly status was a

33 S. Mumford, ‘Ellis and Lierse on Dispositional Essentialism’, Australasian Journal

of Philosophy, 73 (1995): 606-612. 34 S. Mumford, Dispositions (Oxford, 1998), p. 234 ff. 35 Ibid., p. 14. 36 Ibid., p. 122. This means, in particular, that mere ‘Cambridge changes’ are not

allowed. S. Shoemaker also agrees on that criterion; see his ‘Causality and Properties’, in P. Van Inwagen (ed.), Time and Cause (Dordrecht, 1980), pp. 109-135, repr. in Properties, ed. by D.H. Mellor and A. Oliver, (Oxford: 1997), pp. 228-254, p. 232. cf. Evan Fales in Causation and Universals, p. xiii: ‘A physical universal exists if and only if it is a member of the causal “web”; if it is then it exists whether or not it is ever instantiated’ quoted by S. Mumford, Dispositions, p. 123. Let us note that some philosophers do no accept the idea that the causal criterion should be a criterion for the existence of a property. For ex., A. Oliver, ‘The Metaphysics of Properties’, Mind, 105 (1996): 1-80, p. 8.

37 Ellis and Lierse, ‘Dispositional Essentialism’, p. 27. The philosophers they cite are R. Harré and E.H. Madden, as well as Evan Fales, who ‘has argued that the essential properties of the most fundamental natural kinds are their monadic properties, and, in so far as these properties are dispositional, things of these kinds must behave as these properties prescribe’ (E. Fales, ‘Essentialism and the Elementary Constituents of Matter’, Midwest Studies in Philosophy, 11 (1986): 391-402; Causation and Universals (London, 1990). Nevertheless, Ellis and Lierse admit that ‘in the case of the fundamental particles, the dispositional properties may indeed be all that we have’ (Ellis and Lierse, ‘Dispositional Essentialism’ p. 29). Mumford agrees with this. Not only does he admit the possibility of ‘ungrounded dispositions’, but his functional analysis makes him give importance to such functionalist systems as ‘thermostats’ or thermometers whose essence is clearly entirely dispositional (ibid., p 8), i.e. that ‘the exact mechanisms that equip a thermostat with the dispositions it has are, in a significant way, irrelevant to the fact that it is a thermostat.


consequence of their traditional affiliation with an inadequate ontology based on a Humean metaphysic, and a flawed semantics of dispositional terms’ (ibid.). So, what they sought to provide was ‘a more adequate semantics, and an ontologically more satisfactory theory of dispositions – one which allows at least some dispositions to be counted as genuine properties existing in their own right’ (ibid.). Mumford, together with most philosophers trying to rescue dispositions, agrees with the first part of the program: a new semantics for dispositions is needed, which in particular should provide an adequate analysis of the relation (which is not one of equivalence, but of irreducibility38), between disposition ascriptions and subjunctive conditionals. 3. Again, as Ellis and Lierse, and unlike, for example, Hugh Mellor, who thinks that such properties as triangularity which at first sight look categorical, may be viewed as dispositional39, Mumford does not so much attack the Categorical-Dispositional distinction as he tries (1) to explain why it is relevant only as a conceptual (though not a real)40 distinction between ascriptions (ch. 4), (2) to clarify the confusions attached to the concept ‘categorical’41, (3) to fix some criterion for the distinction, namely the following: both dispositional and categorical properties have causal roles. But ‘disposition ascriptions are

Roughly, for something to be a thermostat, it must be sensitive to changes in temperature and be able to trigger a switch if a pre-calibrated temperature threshold is crossed’ (ibid.).

38 S. Mumford, Dispositions, p. 63. See chs 3 and 4 for more details: ‘What I suggest is the rejection of a solely conditional analysis of dispositions and that we treat them as real instantiations of properties which afford possibilities rather than just being shorthand ways of talking about certain combinations of events’.

39 D.H. Mellor, ‘Counting Corners Correctly’, p. 97. Ellis and Lierse note that Mellor’s dispositional foundationalism, which purports to be Humean, faces difficulties: ‘By embracing the Contingency Thesis, Mellor, at the very least, has to subscribe to the view that the laws in this world are only contingently related to the entities that exist in it. Thus, the behaviour of an entity must be logically distinct from the kind of thing it is. Now, if Mellor wants to 1) deny the existence of categorical properties, 2) avoid embracing a behaviourist theory of dispositions, and 3) have an ontology of occurrent properties, then his only option is to identify a disposition with some occurrent property or properties which are not dispositional. But what could these be? Could they be, perhaps, those structural or other properties which must exist if the disposition is to exist?’ (D.H. Mellor, ‘Counting Corners Correctly’, p. 35).

40 He is very careful to distinguish the two levels. See for ex. p. 145: ‘The thesis of property dualism tries to take this distinction (i.e. C-D) further into ontology. Property Monism, on the other hand, is the claim that the conceptual distinction is the only distinction because it denies that there is an ontological division in reality which the conceptual division maps’. ‘There are not distinct categorical and dispositional types of properties but there are distinct categorical and dispositional ways of talking about instantiated properties’.

41 ‘In particular, if “categorical” means “unconditional”, dispositions are, in a very obvious way, categorical: when I say that a particular sugar-cube is soluble, I am in no way making an ascription conditionally for I am saying that it is actually soluble now, not that it could be soluble if some other conditions obtained’, p. 64.


ascriptions of properties that occupy a particular functional role as a matter of conceptual necessity and have particular shape or structure characterizations only a posteriori’ whereas ‘categorical ascriptions are ascriptions of shapes and structures which have particular functional roles only a posteriori’; In other words, ‘our knowledge of the causal roles of the various categorical properties is a complex matter of scientific investigation’.42 Indeed, ‘what is crucial to property monism (the position Mumford adopts) is a justification of the claim that dispositions and their categorical bases are actually the same states of particular things, characterized in two different ways, rather than distinct states in the world’.43 Which, incidentally means that ‘the identity conditions for properties are separated from the identity conditions for predicates’.44 Hence ‘I can know what it is for x to be soluble though I need not know what it is for x to have the particular molecular structure which is a categorical base of solubility, say, xyz. I need not know which molecular structure is involved or even what a molecular structure is, even though “x is soluble” may be true in virtue of the possession of the same state that makes “x has molecular structure xyz” true’. 45 4. Again, another argument by which Mumford seems to agree with Ellis’s version of dispositional essentialism is his rejection of the Continuing existence argument raised by categorical realists to justify the need of categorical bases for dispositions. According to the continuing existence argument, dispositions have existence in between their manifestations only if they are grounded in categorical properties. Indeed, as Ellis and Lierse hold, dispositions need to be based in reality: ‘They must at least be properties of real things. Moreover, it is often the case that things have the dispositions they do because of their internal structures; and in all such cases, we may say that the dispositions are grounded in these structures. However, it is not clear that the basis of any given disposition must, or must, ultimately be non-dispositional. For, without begging the question against non-Humeans, it cannot be assumed that the basis of a disposition does not, or does not ultimately, include other dispositions. For example, the dispositions of an object might well depend on the causal powers of its parts, as well as on how these parts are arranged’.46 So a power could well be grounded in a further power: not all powers need categorical properties as a basis.47 Nevertheless, Mumford is very cautious to distinguish ‘ordinary’ from ‘ultimate’ dispositions. First, because ‘most

42 S. Mumford, Dispositions, p. 77. 43 Ibid., p. 145. 44 S. Mumford, Dispositions, p. 146. At the same time, it implies also, as Armstrong

puts it, ‘the emancipation of the theory of universals from the theory of semantics’, D.M. Armstrong, A Theory of Universals (Cambridge, 1978), p. 6

45 S. Mumford, Dispositions, p. 148. 46 Ellis and Lierse, ‘Dispositional Essentialism’, p. 31. 47 The most detailed analysis of such questions is to be found in G. Molnar, Powers, A

Study in Metaphysics, ed. by S. Mumford (Oxford, 2003) especially chapter 8.


dispositions are of the ordinary variety’,48 so that ultimate dispositions are ‘limited’ (examples of which would be the dispositions of subatomic particles which apparently have no internal constitution that could explain their behaviour). Second, because the history of science shows that mistakes are possible in this respect: ‘We cannot be sure, for any putative ungrounded disposition, whether it is genuinely ungrounded or actually just an ordinary disposition and only thought to be ultimate because of the incomplete state of our physics’.49 Nonetheless, in terms of explanatory requirements and sound methodology we cannot either rule out their existence a priori.50 Even more: ‘The nature of explanation is such that ungrounded dispositions will always have to be posited in order to avoid a regress of explanation and, further, we have every reason, as part of the atomist strategy, to assume that there are genuine ungrounded dispositions. So the function of ungrounded dispositions is to “fill the space” of our process of explanation’ (ibid.). 5. Another important point of agreement in both versions of essential dispositionalism has to do with the indeterminate51 character of most dispositions, either causal52 or stochastic.53 6. But most of all, Mumford agrees with Ellis not only in letting disposition ascriptions play an explanatory role and in conceiving dispositions as units of

48 S. Mumford, Dispositions, p. 229. 49 Ibid., p. 231. 50 Ibid., p. 233. 51 In a deterministic world, this indeterminacy is due to linguistic vagueness. Hence,

‘To define fragility, for example, we cannot do much better than say that a fragile object is likely to break if dropped, or otherwise handled roughly. Any more precise definition might capture some more specific concept of fragility. But it would not be the broad but vague concept with which we are familiar’. On the contrary, in an indeterministic world such as ours, ‘the dispositions are causally indeterminate, not because of vagueness, but because of the indeterminacy of the underlying physical processes. For example, the probability that a radium atom existing at t will have decayed by t + ∂ is, for any given frame of reference, a precisely specifiable function of ∂, and this probability is independent of the circumstances in which the radium atom exists. Hence, we cannot, even in principle, eliminate this causally indeterminate disposition in favour of any more precisely defined dispositions which are causally determinate’ (Ellis and Lierse, ‘Dispositional Essentialism’, p. 42).

52 ‘Where we have a causal disposition, there is typically a certain pattern of cause-and-effect or stimulus-and-response which anything having the disposition would normally display if it were appropriately caused or stimulated to do so’ (Ellis and Lierse, ‘Dispositional Essentialism’, p. 40).

53 ‘A Stochastic disposition is a propensity of some kind, in which the antecedent condition is not strictly the cause of its manifestation, but only a necessary condition for it.’ For example, the disposition of a radium atom to decay in a certain way is a stochastic disposition. If this species of radioactive decay is to occur, it is a necessary condition that radium atomes should exist. But events of radioactive decay are not caused by the existence of such atoms. Not, as far as they know, are they caused by anything else. There is just a certain objective probability p that within any given-time interval ∂ such an event will occur’ (ibid., p. 40).


explanation, but in favoring a dispositionalist account of laws, instead of what he labels the ‘laws view’, namely, the view that laws, conceived as constant conjunctions or natural necessitations of events, are the basic building blocks of explanation.54 Instead, ‘the dispositionalist attempts to dispense with laws of nature by grounding natural necessities within the individual instantiated properties themselves. This gives us the model of instantiated properties as real powers to do things. It is also useful to speak of them as enablements or affordances where this conveys the dispositional notion of causal mediation between events. Thus we have natural necessities without commitment to general laws ranging over classes of events. Instead of general necessities, natural necessity occurs at the level of the particular. It is not in virtue of a general law that sugar dissolves when in a liquid, for instance, it is in virtue of a particular state or instantiated property possessed by that sample that it does so’.55 In various places, Mumford has, quite convincingly, outlined the advantages offered by such a dispositionalist account of laws over both the Humean supervenience view as most strongly defended by David Lewis56 and the Dretske57 – Tooley58 – Armstrong59 (DTA) view of laws, which, despite its challenging the Humean view by taking laws to be real things in nature involving necessary connections between properties, still retained some vestiges of the Humean metaphysic. Now, what are indeed the advantages of seeing laws to be determined by dispositions instead of dispositions being determined by laws? The problems with some laws (I do not deal here with general a posteriori identity statements such as ‘water is H20’ or ‘heat = mean molecular motion’60 but with laws such as ‘all water boils at one hundred degree centigrades’ or ‘all ducks have webbed feet’) are well known: the identification of them with universally quantified conditional statements is doomed to failure. The main challenge to regularity accounts of law is to distinguish coïncidental from genuinely lawlike regularities61 and, secondly, virtually no statements of this form are true.62 As

54 S. Mumford, Dispositions, p. 217. 55 Ibid., p. 221. 56 D. Lewis, Counterfactuals (Oxford, 1973) and ‘Humean Supervenience Debugged’,

Mind (1994). 57 F. Dretske, ‘Laws of Nature’, Philosophy of Science (1977): 248-268. 58 M. Tooley, ‘The Nature of Laws’, Canadian Journal of Philosophy (1977): 667-

698; Causation: a Realist Approach (Oxford, 1987). 59 D.M. Armstrong, What is a Law of Nature? (Cambridge, 1983) and A World of

States of Affairs (Cambridge, 1997), chs 15 and 16. 60 I have analysed the difficulties raised by such statement in ‘La métaphysique et

l’analyse conceptuelle’, Revue de Métaphysique et de morale, numéro spécial: Métaphysique et ontologie: perspectives contemporaines, n° 4, (2002): 559-584, pp. 575-581.

61 See A. Bird, ‘The Dispositionalist Conception of Laws’, Foundations of Science (forthcoming) p. 2. (Preprint available on A. Bird’s web page). The best of these is the


Nancy Cartwright has argued, laws of nature qua general statements would be, for the most part, idealizations and abstractions that should not be regarded as literally true. And the ceteris paribus strategy, in her view, almost amounts to triviality. Getting away from the notion of the statements of laws being general truths, the DTA or ‘nomic necessitation’ version, by construing them as causal relations holding between universals constitutes a progress insofar as it allows realist causal claims that go beyond empirical evidence.63 But the nomic necessitation view does not explain how nomic necessitation entails the corresponding generalisations – it has to stipulate that it does. Moreover, at least in the case of Armstrong’s conception, according to Mumford, although it deals with exception cases (the ‘oaken’ or defeasible laws as opposed to the ‘iron’ laws), it too, like Hume’s and Lewis’s accounts, is ‘committed to reading off the laws from the actual history of events at a world’64 and is caught up in some form of actualism.65 Mumford thinks that a right account of laws must reside somewhere ‘twixt regularity and regulation’, namely between the descriptive regularist view and the theological view concentrating on regulation with laws as God’s prescriptions. In order to qualify as the right interpretation of laws, both somewhat descriptive and prescriptive, viewing these as that ‘which bind the possible and necessary but not the actual in the natural world at which they apply’ (ibid.), a dispositionalist standpoint seems the most appropriate. For example, instead of saying ‘all ravens

systematic regularity theory of Lewis (following from Ramsey), Counterfactuals, pp. 72-77: ‘According to this view, a generalization states a law only if it is deducible from that axiomatic systematization of the facts that optimally combines strength and simplicity’. But, as Bird notes, ‘While this reduces the pressure of the objection from accidental regularities, it does not, remove it altogether. For we could imagine a system of laws that was itself rather complicated and weak but which generated an accidental regularity, whose addition to the axiomatic system might in fact add considerably to its strength without detracting much from its overall simplicity’, p. 2. This objection (and others addressed to the regularity view) is also to be found in Armstrong, What is a Law of Nature?, pp. 66-73.

62 S. Mumford, Dispositions, p. 122 ff. 63 When the relation holds between two universals it entails the corresponding

generalization but the reverse entailment does not. 64 S. Mumford, ‘L’état des lois’, in J.-M. Monnoyer (ed.), La Structure du Monde

(Paris, 2004), pp. 235-262, p. 235. 65 Ibid., p. 256, i.e. ‘the only existence of the law is in what particular causal sequences

occur, so the laws are determined by the events. But then comes a twist. Singular causation was only a ladder enabling us to ascend to the idea of nomicity, which once attained, the ladder can be thrown away. The fundamental causal relation is a nomic one, holding between universals [as Armstrong says in World of States of Affairs: ‘Singular causation is no more than the instantiation of this type of relation in particular cases’, p. 227]. This phrase suggests to me Platonism: causation not between particular instantiations but between universals. Again though, we know that for Armstrong, a universal is nothing more substantial than the sum of its instantiations, so I still do not think that Armstrong escapes actualism. Causation holds between universals, but it can only do so if it has instantiations standing in the right relation’.


are black’, one may drop the requirement that the conditionals associated with law statements must be universally quantified and say instead ‘ravens are black’ without quantification.66 Now there is no need for quantification if we understand such a statement as being not explicitly about a numerable quantity of ravens but as being about the normal dispositional colouring of the species. According to Mumford, such a view fits with scientific practice: namely, the scientist finds a typical representative of some species or kind of thing and then, in carefully controlled conditions, finds out some natural dispositional property of that thing. He is not concerned with amassing more and more cases of black ravens, nor will be troubled by the existence of strange cases, such as an albino.67 Thus, such a notion of ‘the natural behaviour of things’ supplies us with ‘as much regulation as we need for our laws, it gives us a sense of objects having natural governing principles’.68 Indeed, Mumford contends, ‘because of the dispositional force of such governing principles, these dispositions need not be manifested: whether or not they are manifested depends on the contingencies of the world’s history; for instance, on whether the right stimulus conditions are ever realized and whether the correct background conditions are in place’.69 In the second place, ‘what the laws are best understood as descriptive of is not actual or possible events but the capacities of things. Thus, the truth of the claim that a fair coin has a 50/50 chance of landing a head or a tail is true not in virtue of the result of any toss or sequence of tosses, but in virtue of the 50/50 propensity the coin has to land head or tail.…The probabilistic law can thus be explained by it being descriptive of an actual disposition and the account also explains the possibility of unrealized laws. The disposition ascription is true of the coin if it is never tested and thus there can be two true but different ascriptions in two worlds that coincide in all their events’.70 In the third place, ‘there is plenty of logical contingency in these laws: I need not even appeal to another possible world to illustrate this: the laws of nature could change, gradually or instantaneously, on my account... The laws are fixed only by what things (can) do at present. Modalities can be tensed. Thus ravens are black now, meaning that it is true of the raven kind that its normal members are dispositionally black, but tomorrow, through a divine intervention, normal ravens may become dispositionally pink. More naturally, over a period of time, normal ravens may become grey through evolutionary processes... My account leaves open

66 S. Mumford, ‘L’état des lois’, p. 255. 67 Ibid., p. 238-239, p. 255; cf. C.B. Martin, ‘Dispositions and Conditionals’, The

Philosophical Quarterly, 44 (1994): 1-8. Note that C.S. Peirce makes a similar remark: ‘what the chemist is interested in is not the particular sample, but the molecular structure’, The Collected Papers of C.S. Peirce, 8 vols, (Cambridge, 1939-1958), vol. 4, § 530.

68 S. Mumford, ‘L’état des lois’, p. 258. 69 Ibid. 70 S. Mumford, Dispositions, p. 231. ‘Given the realist understanding of such

dispositions, this would be something more than a counterfactual difference’.


the possibility that even the fundamental laws could change…’71 Finally, such a theory meets the ‘desideratum of placing laws somewhere “twixt regularity and regulation”. There is a sense in which laws are about governing principles – that should naturally be the case – but these governing principles are not wholly detached from the world. They are enshrined in the properties natural for class, kind or sort members, hence this can still be called a descriptivist theory of laws. The laws are descriptions of what is natural for classes of particulars but they are not descriptions of events, rather descriptions of what things can do, with a dispositional sense of can’.72 So far so good. But are such arguments wholly convincing? Some Suggestions about the Main Difficulties Dispositional Realism Should be Ready to Face Mumford as well as Ellis or other proponents of the redemption of dispositions intend to confer them a real and not only a fictional status. But what kind of reality have dispositions actually gained? More precisely, are their respective versions of dispositional essentialism or functionalism realistic enough? There are a lot of convincing aspects in Mumford’s account but some are also somewhat puzzling. I shall take them in turn. The Merits of Ontological Deflation or ‘Neutrality’: From Properties to Predicates. It is surely an interesting part of the neutral monistic understanding of dispositions to show how the dispositionality or non dispositionality of a property or state is not a question which is (mainly) grounded in ontology, but is, rather, a matter relative to the predicate with which the property or state is denoted and to the connection between this predicate and the behaviour which is mediated;73 or again that ‘it is not a truth of ontology whether a property is dispositional or not; it can only be a truth about concepts’.74 All the same, as both Ellis and Mumford have observed, such a conceptual reading of the issue does not prevent you from being a realist, as Peirce once also noted, who was one of the first philosophers to attach a particular importance to the reality of dispositions: ‘Anybody may happen to opine that “the” is a real English word; but that will not constitute him a realist. But if he finds that, whether the word ‘hard’ itself be real or not, the property, the character, the predicate hardness is not invented by men,

71 S. Mumford, ‘L’état des lois’, p. 259. 72 Ibid., p. 260. 73 S. Mumford, Dispositions, p. 210. 74 Ibid., p. 213.


as the word is, but is really and truly in the hard things and is one in them all, as a description of habit, or behaviour, then, he is a realist’.75 So indeed, any correct account of the role and nature of dispositions should start with a semantic account of dispositional predicates, as Hugh Mellor also reminded us,76 and, in particular, should try to deal with the reasons why the reduction of dispositional ascriptions to conditionals does not seem to work (for example, due to finkish or antidote cases), or why reduction sentences may or may not tell us ‘all’ that dispositional predicates mean. Suppose, for example, that we know all the manifestations of courage: are we going to be able to say what ‘courageous’ means by summing up all the reduction sentences that say what those manifestations are? Or course not: as Peirce insisted on, a disposition is, by essence, irreducibly general and indeterminate, and cannot be reduced to the mere conjunction of its occurrences. Dispositions as Properties or How should one Understand the Categorical-Dispositional Distinction? But, as Mellor, Ellis or Mumford also insist on, properties are not (or are not given) simply by the meaning of our predicates.77 Nobody would ever think that the planet Mars is, or is part of, or is defined by the meaning of the ‘word’ Mars which we use to refer to it. On the contrary, what gives consistency to the referential capacity of our predicate, when we use it, is that it takes for granted the existence and the identity of planet Mars. In other words, we want a conditional and non verifunctional statement such as ‘if x was dropped, it would break’ to have a truthmaker. This is why Mellor, following Armstrong,78 rejects the Rylean and counter intuitive view according to which when a fragile thing a and a non fragile thing b are not dropped, there is no factual difference between them.79 On the contrary, one should say that if a is fragile and b is not, then a and b, whether dropped or not, must differ in some respect, the most obvious difference consisting in the fact that a has the property of being fragile, which b has not. But how should one explain what that property consists in? To a certain extent, Mumford refuses to commit himself too far. ‘The functionalist theory of dispositions states that nature consists of hierarchically ordered levels where at each level there are entities or properties than can be characterized either dispositionally or structurally and whether they are

75 C.S. Peirce, Collected Papers., vol. 1, § 27, note 1. 76 D.H. Mellor, ‘The Semantics and Ontology of Dispositions’, pp. 757-779. 77 D.H. Mellor, Matters of Metaphysics (Cambridge, 1991), p. 171. See also B. Ellis,

Scientific Essentialism, p. 18, note 1. 78 D. Armstrong, A World of States of Affairs, ch. 6.6. 79 G. Ryle, The Concept of Mind, ch. 5.


dispositional or structural characterizations depends on their explanatory relations to other entities or properties within the whole of which they are a part’ Hence: ‘Relative to the functional role of causing dissolving when in liquid, a denotation of a property P that has that causal role by conceptual necessity - solubility- is dispositional. Denoted in such a way that does not conceptually necessitate that causal role, perhaps in terms of molecular structure, that same property comes out as non-dispositional. By the argument from the identity of causal role, however, these two denotations are of the same state or property instance’.80 In a similar vein, Mellor suggests that properties are neither categorical nor dispositional: they just are. But this is a bit unsatisfactory. To a certain extent, Avicenna had a similar formula when he said that equinitas est equinitas tantum.81 Now everybody knows that the whole problem of universals started from the questions raised by grounding the objective indeterminacy of such a ‘tantum’. It seems too easy, or a way to have one’s cake and eat it, to deny a real distinction between the Categorical and the Dispositional while agreeing that a conceptual distinction is needed, meaning by this that it must have some objective foundation, or that it is more than a distinction of reason, namely, more like what Duns Scotus would have named a formal distinction, that is ‘a distinction from the nature of the thing occurring between two or more really identical formalities of which one, before the operation of the intellect, is conceivable without the others though inseparable from them even by divine power’.82 One way or other, some deep metaphysical issues will have to be handled here with great care.

80 S. Mumford, Dispositions, p. 215. 81 Crucial to Avicenna’s position is the view not so much that essence, as such, may be

considered under two headings, in things and in the intellect, as the fact that it may be viewed as such, in its pure essentiality, neither universal nor singular. The essence (which Duns Scotus, following Avicenna, is to name ‘The Common Nature’ is characterized by such neutrality or indifference towards all its possible determinations, which allows, in particular, to conceive it apart, as a distinct object of thought: ‘ipsa equinitas non est aliquid nisi equinitas tantum’ (Avicenna, Metaphysica, Tract. V, cap.1, fol. 86a.). For more details, cf. C. Tiercelin, ‘Le problème des universaux : aperçus historiques et perspectives contemporaines’, in J.-M. Monnoyer (ed.), La Structure du Monde (Paris, 2004), pp. 329-353, p. 335f.

82 M.J. Grajewski, The Formal Distinction of Duns Scotus (Washington, 1944), p. 93. Such is the best definition given of this difficult Scotistic notion, mid-way between a real distinction and a distinction of reason, through which Duns Scot thinks he was able to 1) avoid the difficulties raised both by extreme (or Platonist) realism and nominalism, 2) understand how individuals (haecceities) can participate to the Common Nature (by contraction) without being reduced by it, 3) ensure the objectivity of our concepts which


Substantival or Relational Realism? Again, the ‘neutral’ monism is in danger of committing itself to more ontology than it would surely be prepared to, at least in the following respect: In Hume’s ontology, there is a sharp distinction between the way a thing is, and how it is disposed to behave: the way it is depends on what its properties are. How it is disposed to behave depends on what the laws of nature are. The two are supposed to be independent of each other.83 Mumford’s general view has the great advantage of trying to account of the changes that occur in the world, from the inside: as he somewhere says, a world described entirely in categorical terms is a static world, and hence, not ours.84 Again, the familiar Humean point that it is a logically contingent matter what effect follows from any antecedent event, and that laws of nature are what is added to animate, so to speak, the world, has something unconvincing about it. This is precisely one of the confusions which Peirce diagnosed in the scholastics’ treatment of dispositions. As is well known, the scholastics (with the maxim operari sequitur esse) claimed that the operations or activities of a thing reflected a corresponding perfection in that thing, which could account for its ability to perform that sort of operation. It was on the basis of this principle that they were able to specify natures and natural classes. If a man performs an action that others animals cannot, such as reasoning, then the man has a power that other animals do not possess. If such a capacity is the distinguishing characteristic, it is dignified with the title ‘nature’. But why did Peirce finally object to the scholastic operari sequitur esse, i.e. to the substantial form as a dispositional character – aside from the question of how scientific one is in determining distinguishing characters?85 Because it failed to reveal the relational structure which is ultimately involved. That is, the scholastics were right, as far as they went, but their limited logic did not allow them to see that the nature, power, or disposition represented in these monadic predicates was only a truncated image of a relational law. Apparently, it was the old logic’s inability to handle abstractions properly that was mainly at fault.86 The scholastics did not realize that their most important abstractions were really hypostatized relations, and therefore that real abstractions indicated real relations – laws and not forms. I am not sure whether Peirce’s substitution of a

remain founded in things and not mere flatus vocis. But this notion of the Subtile Doctor has been severely attacked (by Occam in particular).

83 Cf. Ellis and Lierse, ‘Dispositional Essentialism’, p. 28. 84 S. Mumford, Dispositions, p. 214. 85 C.S. Peirce, Collected Papers, vol. 6, § 361. 86 C.S. Peirce, Collected Papers, vol. 3, § 642. I have analyzed this in ‘L’influence

scotiste dans le projet peircien d’une métaphysique scientifique’, Revue des Sciences Philosophiques et Théologiques, numéro spécial: Jean Duns Scot et la métaphysique classique, n°1 (1999): 117-134, pp. 128-129.


relational realism to a substantival realism is necessarily the correct or only way of handling the problem of dispositions, but at any rate, it is true that there is, in Mumford, a very unelaborated commitment to a view of what an object is in terms of a plain substance, and not much elaboration either on the ‘something’ which justifies or constitutes the truthmaker for a dispositional ascription: is it mere epistemic indeterminacy? Or is this indeterminacy linked with some irreducible, metaphysical features of, for instance, some Common Nature.87 Again, Mumford is obviously committed to a trope theory view of instantiated particulars but neither does he provide an account of the process of instantiation or individuation nor does he present a justification of the reasons why he should rather favor such a view instead of another,88 while admitting that there are notorious difficulties, raised by Russell for example, for a tropist account. The Generality Objection: Contingency or Necessity There are advantages in adopting a dispositionalist view of laws, as Mumford has clearly outlined.89 But the dispositionalist also faces problems: namely, how can he, without general laws, explain why generalities in behaviour are true of kinds? For example, all sugar dissolves in liquid and tastes sweet to the tongue. Is it merely a cosmic coïncidence that each sample of the kind carries the same set of capacities? Could we have rogue samples that possessed different dispositions? Here we face a very serious issue to which I am not sure Mumford provides a

87 See notes 74 and 75. 88 He rejects E.W. Prior’s contention that some identification of properties as

universals is needed. (cf. E.W. Prior, ‘The Dispositional/Categorical Distinction’, Analysis, 42 (1982): 93-96; Dispositions (Aberdeen, 1985), p. 76; E.W. Prior, R. Pargetter and F. Jackson, ‘Three Theses about Dispositions’, American Philosophical Quarterly, 19 (1982): 251-257. ‘Being D need not be the same, in every case, as being C, so long as each instance of the disposition is identical to some instance of a categorical base’. The only problem becomes whether there is some plausible notion of a property instance that can warrant our consent. One candidate notion is that of trope, being an ‘abstract particular’(cf. K. Campbell, Abstract Particulars (Oxford, 1990) or J. Bacon, Universals and Property Instances (Oxford, 1996), such as the redness of a particular apple or the squareness of a particuler window. According to the ontology of tropes, squareness and redness in general do not exist, but only a sum of particular rednesses and squarenesses of things. But, as Mumford himself admits, the problem with such an account is notorious, and was noted by B. Russell: the trope theorist cannot explain how a number of tropes resemble each other. How is it that ten red things are all red, for instance? Or ‘what causes a square peg to fit a square hole? It is not a timeless universal that exists nowhere, rather it is something about this hole and this peg, regardless of what else exhibits a similar quality elsewhere’. (S. Mumford, Dispositions, p. 161). Indeed, but it is precisely on the ‘something about’ that we expect some explanation. Some authors have recently tried to answer such objections adressed to Resemblance Nominalism, in particular G. Rodriguez-Pereyra, Resemblance Nominalism – A Solution to the Problem of Universals (Oxford, 2002).

89 Cf. S. Mumford, Dispositions, p. 221 ff.


satisfactory answer: this has to do, it seems to me, with the contingency of the laws he still wants to maintain in his dispositionalist account. In the last chapter of Dispositions, Mumford clarifies the charge he had adressed in a previous article, namely that Ellis and Lierse argued that dispositional essentialism entailed ‘a definite answer to this debate: that dispositions were ultimate, rather than laws. This involved them making a number of controversial (and poorly justified) claims, such as the laws of nature were logically necessary instead of contingent as the Humean tradition takes them to be’. But, Mumford contends, dispositional essentialism could be true even if it were laws rather than dispositions that were in the relevant sense ultimate or basic. Which does not mean, he hastens to add, ‘that the basic laws view is proved’ or that he was offering a proof, even though in places he ‘pushed that view for dialectical purposes’.90 Further, ‘although basic dispositions as truthmakers of laws are not necessary for the claim of dispositional essentialism about certain fundamental kinds in science, as Ellis and Lierse suggested, …dispositional essentialism may be required for the credibility of the basic dispositions view because it suggests a solution to the generality problem that exists for the basic dispositions view. Hence, basic dispositions are not required by dispositional essentialism but dispositional essentialism may be required for basic dispositions’ (Ibid.). Intricate (or dialectical) as it may sound, such a formulation points to some difficulties one has in understanding Mumford’s exact position as far as the status of laws is concerned, as well as regards the explanatory role he wishes himself to confer to ‘basic’ dispositions. In particular, is Mumford really subscribing to the contingency thesis (CT: the laws of nature are logically contingent) about laws In Dispositions, he explicitly says he endorses it: ‘Although dispositions bring natural necessity in the world there still exists the kind of logical contingency that is required. The replacement of laws with real dispositions is no threat to the view that the way nature behaves could have been otherwise but it does mean that CT will have to be revised accordingly’. Indeed, ‘a modified version of the CT can be given that is framed in terms of the contingency of a particular’s capacities, rather than the contingency of laws’. And he pursues: ‘There exist relevant conceptual necessities of dispositional essentialism, such as that described above where an electron must, conceptually, have certain dispositions if it is to be an electron. Such conceptual necessities do not threaten natural contingency in the sense that the only logical necessities are conceptual. Hence it is logically contingent that a particular entity is a particular with the capacities it actually has. That particular could have had different dispositions to the ones it actually has, even though this would entail that the particular belonged to a different kind in virtue of that fact. Such contingency does not threaten the identities for such entities across possible worlds however, for our disposition ascriptions are actual-world relative’.91

90 S. Mumford, Dispositions, pp. 235-236. 91 S. Mumford, Dispositions, pp. 236-237.


Hence Mumford denies Ellis and Lierse’s move according to which dispositional essentialism requires the logical necessity of physical laws. ‘While it is certainly true that an electron would not be an electron if its behaviour were different from the behaviour it has in the actual world, this necessity is purely conceptual. That it is in virtue of behaviour B that a particular x is classified within a kind K does not entail that x necessarily has behaviour B’(ibid.). According to Mumford, this involves a misunderstanding of the scope of the logical necessity involved. ‘That a particular possesses any disposition is logically contingent even though some particulars, such as electrons, would not have been classed as such if they had a different behaviour. To deny this would be to claim that an electron’s behaviour is dictated by logic, and, presumably, physics is a trivially analytic human folly’ (ibid.). But I do not think that such a criticism is justified, at least, as far as Ellis’s dispositional essentialism is concerned, which indeed does imply some necessitarist account of dispositions, if it aims at presenting kinds of processes as discovered principles active in nature and not as invented classifications. But to a certain extent too, I do not see how Mumford can maintain, even in a reformulated way, the CT about a particular’s capacities. What he may maintain at most (and in fact, it seems to be mainly what he provides as a further account of laws in ‘L’Etat des lois’) are some contingent elements understood as changes or departures from the law. At all events, I doubt that one could go so far as admitting such contingency as the one Mumford alludes too: ‘Thus ravens are black now, meaning that it is true of the raven kind that its normal members are dispositionally black, but tomorrow, through a divine intervention, normal ravens may become dispositionally pink’. Indeed this is making fun of physics or of the laws of evolution. It seems that the contingency Mumford wants to introduce has more to do with what Peirce called ‘conditional necessity’,92 in order to account both of the both descriptive and regulative ‘would-be’ (which was not merely a ‘may be’ or a ‘will be’) character of dispositional laws and of the tychistic or chance elements he deemed necessary to introduce in his both synechistic and evolutionary metaphysics.93

92 C.S. Peirce, Collected Papers, vol. 2 § 664. This is a point recently emphasized by

A. Bird, ‘Necessarily Salt Dissolves in Water’, Analysis 61 (2001): 267-275, and ‘On whether some laws are necessary’, Analysis 62 (2002): 257-274 in response to S. Psillos, ‘Salt dissolves in water, but not necessarily’, Analysis 62 (2002): 255-257. Cf also M. Kistler, ‘The Causal Criterion of Reality and the Necessity of Laws of Nature’, Metaphysica, vol. 3, n°1 (2002): 57-86 and ‘Necessary Laws’, to appear in U. Scheffler and alii. (eds), Principles of Nature (Kluwer, 2004).

93 This is how Peirce intends to explain how, while following the principle of continuity (synechism), laws, in the sense of general indeterminate habits or dispositions do not follow an ironlike necessity, in the course of evolution, but a ‘conditional necessity’, which allows not only some radical spontaneity or chance (tychism) as that of the germinal chaos from which they come, but departures or ‘habit-changes’, these being always conceived, nonetheless, by means of probabilistic laws (on a propensity (or would-be) more


Anyway, should that really be an advantage for the dispositionalist account of laws to try, by all means, to avoid any kind of necessity? For one thing, as we know from Kripke’s and Putnam’s works, a point also recently emphasized by F. Jackson,94 many necessary facts can be known to be true by a posteriori means only: certain identity statements, including identity statements concerning scientific and natural kinds, express propositions that are necessarily true, but that can be known only a posteriori. Hence, in general, as A. Bird has shown,95 the thought that laws might be necessary but knowable only a posteriori is not objectionable and should be familiar from other cases. Furthermore, it can be shown that some96 laws are necessary but have every appearance of contingency: ‘Precisely this relationship can be shown to hold between the existence of salt (sodium chloride) and the law that salt dissolves in water. The underlying law in this case is Coulomb’s law which governs both the electrostatic attraction required for salt to exist and also is sufficient to ensure that salt dissolves in water. Clearly the law that salt dissolves in water is a posteriori and at first sight it seems entirely contingent. But it can be shown to be necessary, even if we assume that the underlying laws are contingent’.97 Whatever we decide in favour of contingent or necessary laws, it remains that one should be careful, when adopting such and such form of dispositional essentialism or realism, not to indulge in what Popper thought was the major defect of essentialism: to aim at providing an ultimate explanation of what reality consists in. In that respect, and although Mumford’s recourse to ‘ungrounded’ dispositions may sometimes sound a little bit like a virtus dormitiva, I prefer to view it less as an invitation to quietism (something like Wittgenstein’s ‘justification must end somewhere’) than as a principle (hence always possibly revisable)98 of sound, fallibilistic methodological procedure.

than frequency model such as a die’s). Cf. C. Tiercelin, ‘C.S. Peirce et le projet d’une métaphysique scientifique évolutionnaire’, Publications de la Sorbonne, Philosophie, 5 (2000): 453-463.

94 F. Jackson, From Metaphysics to Ethics: a Defense of Conceptual Analysis (Oxford, 1998). I have analysed and commented such views in C. Tiercelin, ‘La métaphysique et l’analyse conceptuelle’, Revue de Métaphysique et de Morale, 107, No. 4 (2002): 559-585.

95 A. Bird, ‘The Dispositionalist Conception of Laws’, Foundations of Science. forthcoming, 2005.

96 This qualification is important: it means that, in such a view, one does not have to deny that the fundamental laws are contingent.

97 Cf A. Bird, ibid., p. 8, § 7.1; see also A. Bird, ‘On whether some laws are necessary’, Analysis, 62 (2002): 257-274.

98 Indeed, Mumford seems in more recent texts to be coming to a more critical attitude towards ‘ungrounded’ dispositions and to a revision of his position concerning the contingency thesis about laws, mid-way between Humean lawlessness and nomological realism, in favor of realist lawlessness. See S. Mumford, Laws in Nature (London, 2004).

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