The Southern Journal of Philosophy (1992) Vol. X X X , No. 2

SHOULD HOBBES’S STATE OF NATURE BE REPRESENTED AS A PRISONERS DILEMMA? Andrew Alexandra The University of Melbourne

Introduction In his 1962 book The Logic of Leviathan’ David Gauthier

drew on the resources of games theory as an aid to the pre- sentation of his interpretation of Hobbes’s political philos- ophy.2 Since that book, at least, a number of other commen- tators have done likewise.3 That games theory has been found to be an attractive and useful tool for this purpose is not surprising, for Hobbes’s individualist and instrumental- ist account of rational deliberation and action is strikingly similar to that found in games theory.*

In this paper I wish to consider the appropriate game- theoretic representation of Hobbes’s famous device, the State of Nature, and to show that substantive questions of inter- pretation are involved in that representation. Amongst those commentators who have applied games theory to Hobbes’s political philosophy there appears to be virtually unanimous agreement that the State of Nature should be represented as a Prisoner’s Dilemma. John Rawls goes so far as to claim that ‘Hobbes’s state of nature is . . . the classical example of the prisoner’s dilemma’.5 Others to endorse the claim that the State of Nature can be represented as a Prisoner’s Dilemma include Brian Barry, as well as Edna Ullmann- Margalit, Greg Kavka and Jean Hampton.6 In this paper I argue against this claim. In the first part of the paper I brief- ly sketch Hobbes’s description of the State of Nature, and argue that only two kinds of games, known as the Prisoner’s Dilemma and the Assurance Game, can plausibly be taken as representations of the State of Nature. In the second part of the paper I examine relevant features of these games, drawing on this examination in the third part to argue that,

Andrew Alexandra is Lecturer in the Philosophy Department at the University of Melbourne. His main research interests are the political philosophy of Hobbes and contemporary issues in Political Philosophy. He has published in the History of Philosophy Quarterly.

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contrary to the received view, the Assurance Game should be taken as the preferred representation.

I The State of Nature as a Condition of War

Hobbes uses his description of what he calls ‘the natural condition of mankind’7 (better known as the State of Nature) as a way of illuminating the need for, and the nature of, political authority. The State of Nature is the condition of people who ‘lack a common power to keep them all in awe’.8 Hobbes argues that the State of Nature is a condition of war. According to Hobbes, people are equal in certain respects, which means that each potentially fears the other, and in turn is feared by the other. As he succinctly put it in De Ciue, ‘they are equals who can do equal things, but they who can do the greatest thing, namely kill, can do equal things.’g

There are certain ‘causes of quarrel”0 to be found in hu- man nature-the unlimited exercise of the passions of ‘glory’, ‘competition’ and ‘diffidence’-and without the restraint im- posed by political authority these will render each person’s potential threat to the other actual. This is the condition of war, where each person is a threat to every other person, though physical conflict may or may not occur. This don- dition is graphically, and famously, described by Hobbes in Chapter 13 of Leviathan. In such a condition there is no place for Industry . . . and consequently no culture of the earth, no navigation, no commodious buildings . . . no knowledge of the face of the earth, no account of time, no a h , no letters, no society, and which is worst of all, continual fear and danger of violent death-and the life of man, solitary, poor, nasty, brutish and short.11

Hobbes ascribes to each person a ‘Right of Nature’, which he describes as ‘the liberty each man has, to use his own power as he will himself, for the preservation of his own nature, that is to say, of his own life, and, consequently, of doing anything which in his own judgement and reason, he shall conceive to be the aptest means thereto.’l2 In the con- dition of war a consequence of the Right of Nature is that ‘every man has a right to everything’.I3

Certain passions, namely the overwhelming fear of death, and the desire for commodious living, lead people to wish to escape from or avoid the State of Nature. Reason dictates Laws of Nature, general rules ‘by which a man is forbidden to do that which is destructive of his life, or takes away the means of preserving the same; and to omit that by which

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he thinks it may best be preserved’.*4 In Leviathan Hobbes lists nineteen Laws of Nature, enjoining equity, gratitude, the keeping of covenants and so on. To escape from the State of Nature it is necessary for the

Laws of Nature to be generally accepted as public standards of behaviour, and according to Hobbes this can only be done when all people agree to limit their right to act purely on their own judgement and to act according to the judgment of a sovereign authority.15 The sovereign authority is not itself party to this Social Contract and there is, theoretically at least, no limit to the exercise of its powers. Game-Theoretic Representations of the State of Nature

Hobbes’s State of Nature would seem to lend itself to representation in game-theoretic terms. Games theory purports to model situations of interdependent choice, where what happens to each person is determined partly by themselves-specifically, by their choice of a strategy for action-and partly by others. The State of Nature, ‘a war, as if of every man against every man’, is obviously such a situation of interdependent choice, and since the choices available to people in the State of Nature are few in number and simple in nature they can be represented in game- theoretic terms without undue idealisation.

Those commentators who have depicted people in the State of Nature as ‘players’ in a ‘game’ have characterised the strategies for action available to such players in a variety of ways. Jean Hampton, for instance, dubs the available strategies ‘Invade’ and ‘Not Invade’;16 Edna Ullmann- Margalit speaks of ‘Keeping Covenants’ and ‘Breaking Cove- nants’;17 and so on. My own opinion is that the strategies are more accurately described as ‘retaining the right to judge for oneself which actions are most to one’s advantage’ on the one hand, and ‘not retaining that right’ on the other. Such apparently conflicting descriptions of the available strate- gies are compatible, however: they can be redescribed in broad terms as ‘acting in the way that leads to the condition of war’ on the one hand, and ‘acting in the way that leads to peace’ on the other.

In any case, if it is allowed that the State of Nature can be represented as a two-person game between ‘me’ and ‘you’ (where ‘you’ denotes all, or some sufficiently large number of others, and ‘me’ denotes the individual facing a choice of strategies)18, and that each of the players in this game has two overall strategies available, then there are four possible outcomes (the results of the choice of strategy of ‘me’ and

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‘you’). Thus there will be, it would seem, twenty-four possible rankings of preferences for outcomes. Games are generally individuated by such rankings, so it seems that there are twenty-four game types which could possibly represent the State of Nature.

In fact Hobbes’s description of the S ta te of Nature considerably restricts the number of game types which could represent the State of Nature. According to Hobbesian principles it will always be the case that any outcome which lands players in the State of Nature will be less preferred than any outcome which does not. There are two such State of Nature outcomes. The first of these is the result of ‘me’ and ‘you’ both choosing the ‘bad’ strategy, the one that leads to war-following convention this strategy will be called ‘defection’. Undesirable as the outcome of mutual defection is, it is preferable to the situation where a lone person chooses the ‘good’ strategy, the one which leads to peace- conventionally designated as ‘cooperation’-and conforms his actions to the Laws of Nature, while others do not. Hobbes writes: For he that should be modest, and tractable, and perform all he promises, in such time and place, where no man should do so, should but make himself a prey to others, and procure his own certain ruin.Ig

So while in the general State of Nature everyone is in a state of ‘continual fear, and danger of violent death’ (my em- phasis), the lone cooperator faces certain destruction. The preference rankings for the State of Nature outcomes can, then, be represented as follows:

Me You D D C D

where D denotes ‘defection’, C ‘cooperation’, and where the higher outcome is more preferred.

There are also two possible non-State of Nature outcomes. These could be called ‘Commonwealth’ outcomes-they are general conformity (CC) or lone non-conformity (DC). Since both these outcomes will always be preferred to State of Nature outcomes there are in fact only two possible overall preference rankings for possible outcomes, distinguished according to the ranking given to the two Commonwealth outcomes. These are:

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Prisoner’s Dilemma Assurance Game

1. D C C C 2. c C D C 3. D D D D 4. c D C D

Me You Me You

The first of these preference rankings, where lone defection in the face of cooperation by others is preferred to general de- fection, is that found in the Prisoner’s Dilemma game (hence- forth generally abbreviated to P.D.), while the second, where general cooperation is preferred to lone defection, is that found in the Assurance Game (henceforth A.G.).

Should the P.D. or the A.G. be taken as more accurately rep- resenting the State of Nature? To help answer this question I now turn to a more detailed examination of the two kinds of games.

I1 The Prisoner’s Dilemma

‘Prisoner’s Dilemma’ has come to denote a kind of game which is, more or less, formally analogous to a famous sce- nario, described here by Luce and Raiffa. Two suspects are taken into custody, and separated. The district attorney is certain that they are guilty of a specific crime, but he does not have adequate evidence to convict them at a trial. He points out to each prisoner that each has two alternatives: to confess to the crime the police are sure that they have done, or not to confess. If they both do not confess, then the district attorney states that he will book them on some very minor trumped-up charge . . . ; and they will both receive minor punishment; if they both confess they will be prosecuted, but he will recommend less than the most severe sentence; but if one confesses but the other does not, then the confessor will receive lenient treatment for turning State’s evidence whereas the latter will get ‘the book’ slapped at him.2o

I will now attempt to isolate what I consider to be the for- mally relevant features of this scenario, which can be taken as assumptions generating the P.D.

A) Rationality. (This is implicitly assumed by Luce and Raiffa, as shown in their discussion of the scenario.) “he players are rational in the game-theoretic sense, where ‘of alternatives which give rise to outcomes, a player will choose the one which yields the more preferred outcome, or, more precisely in terms of utility functions, he will attempt to maximize expected utility’.2l

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€3) P.D. Preference Rankings. A player (‘me’) has the fol- lowing preference rankings for outcomes (expressed as or- dered pairs of strategies chosen by two players, ‘me’ and ‘ you’):

Me You 1. D C 2. c C 3. D D 4. c D

C) Independence. Neither player knows what the other intends to do (though it may be possible for them to work it out), nor can either force or cause the other to adopt one strategy or the other.

There are two distinguishable parts of this condition: i) Reciprocal Powerlessness to influence each other’s choice of strategy. ii) Mutual Ignorance of each other’s choice of strategy. This assumption-the assumption of Mutual Ignorance- can in turn be broken into two sub-parts: iia) Isolation-neither player can communicate with the other. iib) Lack of Assurance-even if the players can communi- cate with each other, neither can have assurance that the other’s choice of strategy will in any way be affected by the content of that communication. (So, for example, a promise to choose one strategy rather than another will not, qua promise, have any force.) D) Symmetry. The players are identical in all respects

relevant to their choice of strategy. That is, ‘you’ can be rep- resented as ‘me’ when trying to work out what his choice of strategy will be.22

E) Common Knowledge. Each player knows, or can work out, that features A)-D) hold for each player, and knows that each player knows this, and knows that each player knows this and so on.

Given these assumptions each player will choose his defecting strategy. As can clearly be seen from the columnar lay-out of the preference rankings, this strategy dominates the cooperating strategy-it leads to the more preferred of the two available outcomes if the other player chooses to defect, and likewise if he chooses to cooperate. So each player will take the defecting strategy, and their deliberations will come to rest at outcome 3), which is the only ‘equilibrium

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point’, where ‘each agent has done as well as he can given the actions of the other agents’.23

Although assumption E), Common Knowledge, reflects the contents of the original scenario, it is not essential to the Prisoner’s Dilemma. Since defection is the dominant strategy for each player, they will still each choose that strategy even if they have no insight into the preferences and motivations of the other.

Assumption C), Independence, is the most complex of the P.D. asssumptions in its specification. Its articulation is contingent upon the other P.D. assumptions, and in partic- ular upon the actual preference rankings of the P.D. In some games with different preference rankings-for example the Assurance Game, discussed below-overcoming Isolation is sufficient to overcome Independence. In such games, where players can communicate with each other they can commit themselves to strategies which it is clearly in their interests actually to play. Lack of Assurance is not a problem-the second player can see that the first has good reason to take the strategy which he has said that he will. The second player is thereby constrained, for better or worse, in his choice of strategy. Overcoming Isolation destroys both Lack of Assurance and Powerlessness-in such cases, knowledge really is power.

Where P.D. assumptions hold, however, even if Isolation can be overcome, Lack of Assurance, and hence Ignorance, will obtain. Given the assumptions of Rationality and P.D. Preference Rankings each player can see that both are better off if both choose to cooperate rather than to defect. If Isolation is overcome each will be able to communicate his acknowledgement of this fact, and to express his intention to cooperate, conditional on the other doing likewise. Nevertheless, such communication will be insufficient to actually move either player, given their P.D. Preference Rankings defection remains their dominant strategy, so again mutual defection will be the outcome.

* * * As I have represented it ‘the Prisoner’s Dilemma’ is mis-

named. For where is the dilemma? According to the O.E.D. the popular meaning of ‘dilemma’ is a ‘choice between two alternatives which are equally unfavourable’. Players in games such as the P.D. choose between strategies, and in a sense there is no such thing as an unfavourable outcome, there are simply more or less preferred ones. In some games a player is faced with a choice between equally preferred

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strategies, but that is not the case with the P.D. Since there is no need to choose between equally preferred strategies there is, a fortiori, no need to choose between equally un- favourable ones. There can be no doubt or perplexity about what to do-each will choose the defecting strategy.

The P.D. has generated much interest as a model for real- life situations, where it does appear more dilemmatic, with the pursuit of individual self-interest leading to an outcome that is preferred less by each than some other possible out- come-where, in effect, people arrive at the outcome of mu- tual defection rather than the more preferred one of mutual cooperation. Let us call the problem of achieving mutual cooperation rather than mutual defection ‘the practical prob- lem’. Given the P.D. assumptions outlined above, the prac- tical problem is intractable.24 However many real-life situa- tions which have been seen as prima facie Prisoner’s Dilem- mas possess features which allow the practical problem to be solved. This is particularly the case where two, or some other small number of people, are involved.25

When two people find themselves in a situation where their preferences towards the possible outcomes of their actions are as for the P.D. they can often communicate with each other, to discover that they both express an intention to choose the cooperative strategy conditional on the other do- ing likewise. In such cases Isolation is not a problem. The communication of this intention generally justifies each in actually choosing the cooperative strategy-each regards the other’s say-so as good evidence of their intention, and given that he believes that the other will choose the cooperative strategy feels bound to do likewise.

That is, the general presumption of trust between people is typically sufficient to solve the practical problem in real- life two-person cases where Isolation is overcome. There are two broad ways of explicating how trust affects the practical reasoning of those in the sort of situation under considera- tion. According to the first, which could be called a deonto- logical account, the effect of the speech-act of promising, for example, is to restrict the class of reasons which are relevant to an agent’s decision: only those consistent with the promise are to be taken under consideration.26

While the deontological account claims that trust acts to narrow the focus of considerations relevant to decision, the second account, consequentialist in nature, explains the workings of trust in terms of a widening of this focus. On this account Luce and Raiffa’s scenario ignores the fact that we live in a social world, where our actions may be observed,

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and these observations taken into account by others when they contemplate future dealings with us. The possibility of gaining a reputation as untrustworthy, unreliable and so on may be very much against our long-term interests. Conse- quentialist considerations may lead to an agent preferring, all things considered, to cooperate rather than defect. Whether they do, of course, depends on contingent factors such as how much the agent values present gains as against future losses, and how likely he considers it that breaking trust will be detected; in short, on the expected utility of the available adions.27

The difference between the two accounts of the workings of trust can be expressed in terms of the P.D. assumptions outlined above. Both agree that the assumption of Indepen- dence is overcome by communication. The effects of this com- munication are, however, differently described. The deonto- logical account denies the applicability of the assumption of Rationality-to understand people’s reasoning in such cases it is not sufficient to see them always as acting to maximise expected utility. The consequentialist approach on the other hand denies the assumption of P.D. Preference Rankings. In the context of the broad choice situation the available strategies should be described not simply as ‘cooperate’ or ‘defect’, but as, say, ‘cooperate after having promised to do so’. Strategies under these descriptions will differ from P.D. Preference Rankings.

* * * The practical problem is familiar enough to us. We

encounter it at times of power restrictions, water shortages and so on, where the desire by each to continue to enjoy unrestricted use of a limited good may lead to a curtailment, or total loss, of that good for all.

The conditions which make the solution of the practical problem possible in small groups are often lacking in large groups. The problems of Isolation and Lack of Assurance are, typically, more difficult to overcome in large groups. Obviously Isolation is a greater problem in large groups. Even where Isolation may be overcome, Lack of Assurance will remain a problem in many large groups whenever con- sequentialist considerations are relevant. Such considerations affect preference rankings only when sanctions or rewards can be both effectively and appropriately assigned. Such assignation depends on the possibility of accurately iden- tifying the agent and his action; and on the possibility of actually imposing sanctions or rewards. Neither possibility

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will be fulfilled in many of the interdependent choice situations typical of modem societies, involving large groups of anonymous agents-as in power-restriction type cases. Even where an individual’s action ,can be accurately identi- fied by some members of a large group, unless it is possible to make this information generally known-and in such groups that often will not be possible-it may have no effective impact on that individual.

A ‘third party’ may be required to solve the practical prob- lem for a group which is unable to do so itself. Such a third party will be able to seek out information and impose sanc- tions to guarantee general conformity: I take it that the State, for example, plays this role in power-restriction type cases. The Assurance Game

I will now consider the Assurance Game and its relation to the Prisoner’s Dilemma. The assumptions of Rationality and Symmetry, as outlined in the discussion of the P.D., can be taken as given. There is a difference between the preference rankings for outcomes in the two games:

B1) Assurance Game Preference Rankings

Me You 1. c C 2. D 3. D

C D

4. c D

This differs from the P.D. rankings only in the ordering of the first two outcomes. This difference, however, profoundly influences the nature of the game. Unlike the P.D., there are two equilibrium points (CC and DD) and no dominant strategy. As argued above, in the P.D., since defection is the dominant strategy, mutual defection will be the outcome, whether or not the assumption of Common Knowledge holds. In the Assurance Game, on the other hand, the players’ choice of strategy is contingent on what they know about each other. If the assumption of Common Knowledge holds, then each can choose the cooperative strategy in the con- fident expectation that the other will do the same, since neither has anything to gain from doing otherwise. Thus each will gain his most preferred outcome. In terms of the assumptions outlined above, given Rationality, Symmetry and A.G. Preference Rankings, then Common Knowledge leads to the overcoming of Independence.

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Where Common Knowledge does not apply the players may not choose to cooperate. The principles of strategy choice they use depends on the attitudes they take to the possible outcomes in themselves, not simply in terms of their standing in the preference rankings. Where one outcome is perceived as highly undesirable the principle of ‘maximin’ may be chosen. This recommends choosing the ‘best worst’ outcome: in this case choosing defection, for fear that other- wise one will be a lone cooperator. Maximin is a controver- sial principle, since it seems to rule out such apparently Tea- sonable actions as gambling on a favourable outcome when the rewards of such an outcome are immense and the draw- backs of the least favoured outcome negligible. However, when the possible outcomes produced by the other player’s choice of the strategy which the first would least have pre- ferred him to have chosen can reasonably be seen as ex- tremely undesirable, maximin gains more plausibility. (It is reasonable, for example, to think that a person in a Hobbes- ian State of Nature deliberating about his choice of strategy should allow himself to be guided by maximin to choose defection-Hobbes emphasises the dire consequences of conforming to the various Laws of Nature in such a situation where others do not.)

So in A.G. type situations where Common Knowledge does not apply but where maximin considerations do, each will choose to defect. In the Prisoner’s Dilemma the choice of the defecting strategy is determined by two considerations: the fear of the results of lone cooperation, and the desire for the benefits of lone defection-the desire to be a ‘free rider’. Both of these considerations may be live for each player in an Assurance Game as web again they may fear the results of lone cooperation, and though not attracted to free riding themselves, where they cannot be sure that others won’t free ride-where they lack Common Knowledge-the fear of lone cooperation will drive them to defection. So the mere availability of lone defection in Assurance Games where players lack Common Knowledge will lead to the practical problem-where mutual defection is the outcome, even though each would prefer mutual cooperation.

The practical problem as it arises in the A.G. can be solved by the intervention of a third party, as in the P.D. The task of the third party here, however, is not to affect preference rankings, as in the P.D., but simply to make the information available to the interested parties which will enable them to achieve mutual cooperation.

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I11 The P.D. Reading: Attractions and Problems

The weight of critical opinion holds that Hobbes’s State of Nature should be represented as a Prisoner’s Dilemma. What are the attractions of this claim? They are, I think, twofold. Firstly, it fits with a popular interpretation of Hobbes which sees him as holding that people are by nature selfish and anti-social. Secondly this view appears to be con- sistent with, and to make sense of, Hobbes’s views on the nature and role of the sovereign. Everyone knows that Hobbes’s sovereign is absolute-now it seems that we can see why this is, and at the same time why it is rational for people to accept such an unlimited ruler. Because people are by nature aggressors the sovereign will have to be harsh and authoritarian, to guarantee the cooperative behaviour necessary to keep people out of the State of Nature-he will have to show that the benefits of selfish behaviour are outweighed by the penalties which he will impose for such behaviour.

This might be called the vulgar view of Hobbes-it is the one that seems to have passed into general currency. It has its sophisticated exponents, however (and not only among those who subscribe to the view that the State of Nature can be seen as a P.D.). So, for example, this view is neatly expressed by David Gauthier when he writes: Hobbes takes seriously the view, implicit in many bourgeois thinkers, that all men are mutually selfish. The resultant harmony of interests is imposed, not by an invisible hand, but by the very visible hand of the absolute sovereign.2s

Ullmann-Margalit explains the sovereign’s role in the lan- guage of games theory: owing to the sovereign’s unlimited right of sanction, the pay-off structure of the situation changes in such a way that once the transition into the State of Peace takes place, the situation is no longer P.D. structured. The belligerent policy no longer dominates the peaceful one-the State of Peace is rendered ~table.~9

The view of human nature which such writers attribute to Hobbes is, to say the least, controversial. And in so far as it is an essentialist view (people are by nature selfish, ag- gressive and so on) it implicates Hobbes in blatant self-con- tradiction-since officially Hobbes’s position is relativistic.

Hobbes claims, ‘of the voluntary acts of every man the object is some good to himself‘.30 Hobbes is, theoretically at

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least, a complete relativist and subjectivist about the objects which people may take as goods. To say that the objects of voluntary acts are goods to the agent is a purely formal claim; it does not rule out any particular object being taken as a good, so it does not rule out, for example, people acting for altruistic or friendly motives.

Hobbes is a subjectivist, holding that the ascription of value is dependent on the interests of the valuer: But whatsoever is the object of any man’s appetite; that is in which he for his part calleth good . . . these words good, evil and contemptible are ever used with relation to the person that useth them: there being nothing simply and absolutely so; nor any common rule of good and evil, to be taken from the nature of the objects themselves.31

Hobbes holds not just that valuation is relative to the valuer, but that it is relative to the valuer’s particular situation: Good and evil are names that signify our appetites and aversions; which in different tempers, customs and doctrines of men are different . . . Nay, the same man, in diverse times, differs from himself; and one time praises, that is, calls good, what another time he dispraises, and calls evil. 32

The A.G. Reading: Textual Support If the State of Nature is represented as a many-person

Assurance Game played without Common Knowledge then it is possible to read Leviathan in a way which is both more in sympathy with Hobbes’s professed intentions and more inherently plausible than the reading suggested by those who represent the State of Nature as a Prisoner’s Dilemma. On the suggested reading it is not necessary to see Hobbes as having an essentialist view of human nature, and it is possible to make sense of the role of the sovereign without supposing that he exists simply to deter people from in- dulging their naturally selfish impulses.

To make this reading of Hobbes convincing it is necessary firstly to show that people in the State of Nature lack Com- mon Knowledge; then to explicate the function of the sov- ereign, consistent with Hobbes’s statements on the subject.

The State of Nature is simply the Commonwealth with the ‘common power’ removed. Hobbes writes that ‘It may be per- ceived what manner of life there would be, where there were no common power to fear, by the manner of life which men that have formerly lived under a peaceful government, use to degenerate into, in a civil war’.33

The State of Nature can be seen as inherent in the Commonwealth, whether or not it ever becomes actual. The Commonwealth is of its essence a large organisation-it

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must be if it is to deter invasion by outside forces.34 Problems of isolation, the inability to know those who may affect us, or to have insight into their motives, are inherent in such groupings. As F. S. McNeilly has put it: Hobbes is not an observer predicting on the basis of the known, but an analyst of the deliberation of a participant faced with the unknown. All that is postulated is a reasoning being having a number of objectives and in contact with similar beings.35

It is the function of the Laws of Nature to regulate the relationships between people in large groups. ‘These are the laws of Nature, dictating peace, for a means of the conser- vation of men in multitudes, and which only concern the doctrine of civil ~ociety’~6 (my emphasis).

The fundamental role of the sovereign, on the A.G. read- ing, will be that of a coordinator. Chapter 30 of Leviathan, entitled ‘Of the Office of the Sovereign Representative’, is probably Hobbes’s most coherent statement on the role of the sovereign, and it does appear to support the claim that Hobbes sees people as capable of uncoerced cooperation. He asserts that the sovereign was trusted with power for ‘the procuration of the safety of the people. . . . But by safety here is meant not a bare preservation, but also all other content- ments of life, which every man by lawful industry, without danger or hurt to the Commonwealth, shall acquire to himself’.37 The sovereign procures such safety ‘not by care applied to individuals further than their protection from injuries, when they shall ~omplain’~8 but rather by public instruction and the making of good laws. Hobbes’s views on both these sovereign functions, law-making and instruction, indicate that he thought that people at least had the poten- tial to run their own affairs with the minimum of govern- mental interference. In his discussion of the need for public instruction Hobbes praises the capacities of the common people, claiming that he should be ‘glad that the rich and potent subjects of a kingdom, or those who were accounted the most learned, were no less incapable than they’.39 So certainly such people will, if properly instructed, understand the need for following the Laws of Nature (acting coopera- tively). Similarly in his discussion of good laws Hobbes in- sists that in matters which do not impinge on external af- fairs ‘the best counsel . . . is to be taken from the general information, and complaints of the people of each province, who are best acquainted with their own wants’, and he in- sists that ‘the use of laws . . . is not to bind the people from all voluntary actions, but to direct and keep them in such

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a motion as not to hurt themselves by their own impetuous desires, rashness or indiscretion, as hedges are set, not to stop travellers, but to keep them in the way’.40

NOTES

1 David Gauthier, The Logic of Leviathan, Oxford, OUP, 1962. 2 In this paper I consider only the statement of that philosophy found

in Thomas Hobbes, Leviathan, ed. C. B. McPherson, London, Penguin, 1980. Originally published 1651. For convenience I have not always followed the original typography or s.pelling

3 Those I focus on m this paper are: Edna Ullmann-Margalit, The Emergence of Norms, Oxford, Clarendon Press, 1977; Greg Kavka, Hobbesian Moral and Political Theory, Princeton, Princeton University Press, 1986; Jean Hampton, Hobbea a d the Social Contract Tradition, Cambridge, CUP, 1986.

4 The seminal work in games theory is J. Von Neumann and 0. Morgenstern, Theory of Games and Economic Behavior, Princeton, Princeton University Press, 1953. More accessible works, from which the simple gametheoretic concepts in this paper have mainly been drawn, are R. D. Luce and H. M a , Games and Decisions, New York, John Wiley and Sons, 1957; D. Lewis, Convention, Cambridge, Mass., Harvard University Press, 1969; M. Bacharach, Economics and the Theory of Games, London, Macmillan, 1976. For Hobbes’s account of reasoning and action see Chs. 5-8 of Leviathan, op. cit., especially Ch. 6, p. 127, Ch. 8, p. 139, and Ch. 14, p. 197.

6 John Rawls, A Theory of Justice, Oxford, OUP, 1976, p. 269. 6 Brian Barry, Political Argument, London, RKP, 1965, pp. 253-254, Edna Ullmann-Margalit, .The Emergence of Norms, op. cit., pp.

62-73; Greg Kavka, Hobbesian Moral and Political Theory, op. cit., p. 109; Jean Hampton, Hobbes and the Social Contract Tradition, op. cit., pp. 80- 81. On the other hand, David Gauthier in The Logic of Leviathan, op. cit., pp. 76-88, denies that people in a State of Nature are actually in a P.D. type situation, though they may believe, and act as if, they are. Rather (though Gauthier does not use this terminology) their situation ia better represented as an Assurance Game (see the matrix on p. 85). So Gauthier’s response to the issue at hand and the one given in this paper are broadly in agreement, though there are considerable differences in detail and emphasis.

7 T. Hobbee, Leviathan, Ch. 13, p. 183. 8 Ibid., p. 184. B Ibid., p. 185. 10 T. Hobbee, De Cive, Ch. 1.3 in Man and Citizen, ed. B. Gert, Brighton,

Sussex, Harvester Press, 1972, p. 114. 11 Ibid., Ch. 13, p. 168. 12 Ibid, Ch. 14, p. 189. For a more detailed discussion of the Right of

Nature, see D. J. C. Carmichael, The Right of Nature in Leviathan’ in The Canadian Journal of Phibsophy (18) June 1988, pp- 257-270.

18 Leviathan. op. cit., p. 190. 14 Ibid., p. 188. 15 Here I follow Carmichael in ‘The Right of Nature in Leviathan’, op. cit. 16 J. Hampton, Hobbes and the Social Contract Tradition, op. cit., p. 61. 11 E. Ullmann-Margalit, The Emergence of Norms, op. cit., pp. 62-73. 18 The validity of representing some many-person games in a two-person

format is further discueeed below.

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l 9 T. Hobbes, Leviathan, op. cit., Ch. 15, p. 215. 2o R. D. Luce and H. Raiffa, Games and Decisions, op. cit., p. 95. 21 Ibid., p. 50. 22 It is worth noting that this feature of the P.D. means that the two-

person representation of P.D. preference rankings given above is also suitable for representing the preference rankings of participants in many- person P.D.s, with ‘me’ denoting each of a group in turn, and ‘you’ the rest.

D. Lewis, Convention, op. cit., p. 8. 24 I agree in this with L. Sowden, ‘That There is a Dilemma in the

Prisoner’s Dilemma’, Synthese 55 (1983) 347-352, contra L. Davis, ‘Prisoner’s Paradox and Rationality’, American Philosophical Quarterly 14 (1977) 319- 327. Cf. the discussions by Hillel Steiner, ‘Prisoner’s Dilemma as an Insoluble Problem’, Mind XLI (1982) 285-286; David Gordon, ‘Is the Prisoner’s Dilemma an Insoluble Problem’, and J. P. Porter, ‘Relevant Interest and the prisoner’s Dilemma’, both in Mind XCII (1984) 98-100.

25 For convenience I will discuss only two-person cases: the way in which the discussion can be generalised in games between small numbers will be obvious.

26 On the nature of such ‘exclusionary reasons’ and their role in practical reasoning see Joseph Raz, ‘Reasons for Actions, Decisions and Norms’ in J. Raz (ed.), Practical Reasoning, Oxford, OUP, 1978, pp. 128-143.

27 Two-person P.D., where the agents are known to each other and where the choice situation will be reiterated an indefinite or infinite number of times, provides a clear case where, if agents are guided by consequentialist considerations, then the cooperative strategy is most advantageous for each. Each can affect the other’s choice of strategy, punishing the other by defecting if he has defected at the previous stage, and rewarding him by cooperating if he has done likewise at the previous stage. For the long-term effectiveness of this tit-for-tat strategy see R. Axelrod, The Evolution of Cooperation, New York, Academic Press, 1984, esp. 192-215. As I in effect argue below, this argument may not be generalised for all many-person reiterated P.D.5.

28 D. Gauthier, The Logic of Leviathan, op. cit., p. 90. E. Ullmann-Margalit, The Emergence of Norms, op. cit., p. 67; simi-

larly, Hampton writes: ‘even shortsighted people unable to appreciate the long-term benefits of cooperation can at least appreciate the short-term consequences of the sovereign’s sanctions against reneging and will therefore find it in their best interests in the short run and the long run to keep their parts of the bargain. . . . the sovereign’s sanctions mean that keeping a contractual promise is no longer a prisoner’s dilemma’. Jean Hampton, Hobbes and the Social Contract Tradition, op. cit., pp. 132-133.

30 T. Hobbes, Leviathan, op. cit., p. 192. 31 Ibid., Ch. 6, p. 120. 32 Ibid., Ch. 15, p. 261. 33 Ibid., Ch. 13, p. 187. 34 Ibid., Ch. 17, p. 234. 35 F. S. McNeillv. The Anatomy of Leviathan, New York, McMillan, 1968, . . - .

p. 165. 36 T. Hobbes, Leviathan, op. cit., Ch. 15, p. 214. 37 Ibid.. Ch. 30. D. 376. _ - 38 Ibid.’ 39 Ibid., Ch. 30, p. 379. 40 Ibid.

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