What does the Fool say to Thomas Hobbes in Chapter 15 of Leviathan?
The Fool is an antagonist introduced by Hobbes in Book XV, Part 1 of Leviathan. In so introducing this figure, Hobbes is putting forward a possible objection to his own ethical thesis, which states unequivocally that rationality is ultimately grounded in self-interest.
The Fool, accepting Hobbes's notion at face value, takes matters to their logical conclusion, insisting that if practical reason is indeed grounded in self-interest, then it is perfectly rational to act in one's own interests, even if that ultimately entails breaking the covenant into which men have entered with the all-powerful sovereign. To this end, the Fool's conclusion is stark: there is no justice—not even the somewhat limited conception advanced by Hobbes.
In terms of moral philosophy, the antagonism between Hobbes and his fictional interlocutor closely resembles an important distinction between deontological and consequentialist ethics. The Fool conceives rationality as inhering in the act itself, irrespective of the damaging consequences that may ensue. To that end, he may be understood as a kind of deontologist, albeit in relation to purely rational, as opposed to moral conduct. In other words, the act, rather than its consequences, is the thing.
Hobbes, on the other hand, is something of a consequentialist, propounding what amounts to a utilitarian ethic avant la lettre that looks to the results of moral acts, rather than examining any intrinsic worth they may have. And it is this consequentialist standpoint that forms the basis of Hobbes's attempted refutation of the Fool. The selfish actions of an individual, however ostensibly rational they may appear, can lead not just to self-destruction, but also threaten the very fabric of the fragile covenant between man and sovereign that establishes a peaceful and ordered civil society. In both cases, the Fool's fetish for what he perceives to be rationally based self-interest is ultimately very far from being in his own interest at all.
In other words, for Hobbes, unlike the Fool, what matters are the reasonable expectations of the agent in making a moral decision rather than the purported rationality of the act itself. In that sense, both actual and (reasonably) expected consequences need to be taken into consideration in order to gain a fuller understanding of justice.
In this chapter, the Fool says (not necessarily to Hobbes himself) that there is not really any such thing as justice. He says that people might as well just do whatever is useful for them. The Fool argues that there is no reason that people should keep their word and adhere to the terms of the covenants or contracts that they have made.
This is in direct contradiction to what Hobbes gives as the third law of nature. The third law of nature says that people must follow the terms of the agreements that they make. This, to Hobbes, is justice.