PHIL 41150: Political Philosophy
Dr. Robert Lane
Lecture Notes: Friday February 21, 2003

[4.] The State of Nature is a Prisoner's Dilemma. (Leviathan ch.14).


[4.1.] Laws and Rights of Nature.


In Lev ch.14-15, Hobbes identifies "Laws of Nature": these are general principles (i) that are revealed by reason and (ii) that describe behavior that is in one's best interest:


The passions that incline men to peace, are fear of death; desire of such things as are necessary to commodious living; and a hope by their industry to obtain them. And reason suggesteth convenient articles of peace, upon which men may be drawn to agreement. These articles, are they, which otherwise are called the Laws of Nature... (Ch.13 14, p.404, emphasis added)


A LAW OF NATURE, (lex naturalis,) is a precept, or general rule, found out by reason, by which a man is forbidden to do that, which is destructive of his life, or taketh away the means of preserving the same; and to omit that, by which he thinketh it may be best preserved. (Ch.14 3, p.404, emphasis added)


These "laws" are not absolute -- they merely "bind to a desire they should take place" (ch.15, 36, p.414), i.e.

         they are principles that a rational being would desire everyone to follow;

         but in the absence of reasonable assurance that everyone else will follow them, you yourself have no obligation to follow them.


         first law of nature: "to seek peace, and follow it"

         second law of nature, "that a man be willing, when others are so too, as farforth, as for peace, and defence of himself he shall think it necessary, to lay down this right to all things; and be contented with so much liberty against other men, as he would allow other men against himself." (5, pp.404-405)


The right to which Hobbes refers in the second law follows from what he calls "the right of nature":


         "The RIGHT OF NATURE ... is the liberty each man hath, to use his own power as he will himself, for the preservation of his own nature; that is to say, of his own life" (1, p.404)

The right that follows from this is a "right to all things": "there is nothing he can make use of, that may not be a help unto him, in preserving his life against his enemies; it followeth, that in such a condition, every man has a right to every thing: even to one another's body." (Ch.14 4, p.404)



[4.2] Prisoner's Dilemmas.


As Hobbes describes the situation:

         what would benefit everyone the most would be for all to "lay aside the right of nature," i.e. to agree to a truce and then stick to it;

         but it would be irrational for any given individual to agree to a truce and then abide by it, since there is no guarantee that others will do the same;

         so if each individual does what's in his own rational best interest, everyone ends up worse off as a result.


This sort of situation, in which the rational actions of rational individuals make everyone worse off than if they had behaved irrationally, is called a prisoner's dilemma.


[4.2.1.] The Original Dilemma. The phrase "prisoner's dilemma" was coined in the 1950s to describe this scenario:[1] Suppose you are arrested by the secret police, beaten and thrown into a cold, dark cell in the basement of police headquarters. Hours later you are taken to an interrogation room. "You are being charged with treason," says the interrogator. "We have also arrested your friend Axel. He is in another part of the building now and is also charged with treason. We demand that you confess, and we offer you the following deal. We are also making Axel the same offer..."


If Axel confesses and

A. you confess... you get five years.

B. you don't confess... you get ten years.

If Axel doesn't confess and

C. you confess... you get one year.

D. you don't confess... you get two years.


Should you confess, or not? If you:

         assume that everything the interrogator tells you is true;

         assume that you have no way of knowing what Axel will do and that you have no way of communicating with him; and

         make the decision entirely on the basis of what is best for you (what will get you the shortest sentence)


The solution: no matter what Axel does, you're better off confessing.



You do not confess

You confess

Axel does not confess

A-2, you-2

A-4, you-1

Axel confesses

A-1, you-4

A-3, you-3


The numerals indicate where each scenario ranks with Axel and with you; "1" indicates best and "4" indicates worst; Axel's rank is given first, yours is given second. E.g., the situation in which you confess but Axel does not is "1" for you and "4" for him (you get one year but he gets ten).


Why this is a dilemma:

         Axel is in the same position as you--the police have made him the same offer.

         If he acts in his own best rational interest, he will also confess, in which case you both get five years.

         But if neither of you had confessed (if neither had done the rational thing), each of you would only get two years. You would both be better off if neither of you had not done the rational thing!


Even if you could somehow communicate with Axel and agree both not to confess, you still don't know that, once you are separated again, he will keep his end of the agreement. Either way, you are better off breaking the agreement yourself! So both rational agents will end up confessing and thus both be worse off than they would be had neither one of them done the rational thing.


[4.2.2.] The Dilemma in the State of Nature.


You and Axel are individuals living in a state of nature. You are considering whether to attack Axel and base your decision on what will be in your own rational best interest. There are four possible scenarios:


Axel attacks and

A. you attack...

B. you don't attack...

Axel doesn't attack and

C. you attack...

D. you don't attack...


Should you attack, or not? If you:

         assume that you have no way of knowing what Axel will do; and

         make the decision entirely on the basis of what is best for you (what will gain for you the most resources)

No matter what Axel does, you're better off attacking.



You do not attack

You attack

Axel does not attack

A-2, you-2

A-4, you-1

Axel attacks

A-1, you-4

A-3, you-3


This is why conflict between you and Axel (two individuals living in Hobbes' state of nature) would inevitably result from each behaving rationally: no matter what the other individual does, each will be better off if he attacks the other -- even if they've agreed to a truce!


So both rational agents will end up attacking and thus both will be worse off than they would be had neither one of them done the rational thing.



[4.2.3.] Escaping the Dilemma.


An individual in the state of nature cannot guarantee the best case scenario for himself (he attacks and others don't) -- there's always the risk he'll find himself in the third best scenario (everyone attacks everyone). What each individual needs is a way of guaranteeing the second-best scenario, in which no one attacks. On Hobbes' account, this is the purpose of the social contract, by which a commonwealth (civil society) is brought into existence: it provides a way out of the prisoner's dilemma by providing an assurance, in the form of an authority that makes and enforces the laws, that others will keep their agreements with you (and that you will keep yours with them).


[1] Games with this structure were developed by Merrill Flood and Melvin Dresher (Hampton refers to Flood, "Some Experimental Games," Management Science 5 (October 1958): 5-26) ; the version with prisoners, as well as the name "prisoner's dilemma," is due to Albert W. Tucker. For more on prisoner's dilemmas, see Kuhn, Steven; "Prisoner's Dilemma", The Stanford Encyclopedia of Philosophy (Winter 2001 Edition), Edward N. Zalta (ed.), URL =

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