Why should one be moral? This question is nearly as old as the discipline of moral philosophy itself; it has been troubling ethicists ever since Glaucon challenged Socrates to disprove that “the life of the unjust man is much better than that of the just.” To find an answer to the question of why one should be moral has been taken to be one of the most fundamental tasks of moral philosophy. And even a casual survey of the history of ethics will reveal that there are many ways of trying to answer the question.

In Plato's Republic, Socrates argued that true artisans work not in their own interest but for the good of that upon which they practice their art. So the true ruler is one who works for the good of the city or the citizens, not the ruler's own self-interest. Many would hold, with Leo Strauss, that Machiavelli contends the very opposite — that for him the true prince ruthlessly seeks self-interest and personal power. I think this is too simple a reading of Machiavelli.

I do not want to argue that Machiavelli is not a Machiavellian — that he does not counsel evil. But I do want to argue that Machiavelli's advice to the prince is to avoid self-interest. The prince is encouraged to act for the good of the state. It is true that in Machiavelli's opinion this will often require doing evil, and it is also true, one must admit, that Machiavelli does not really expect the prince to succeed in avoiding self-interest.

1 Introduction

Numerous solutions have been proposed to the semantic paradoxes. Two that are frequently singled out and compared are the following. The first is that according to which paradoxical sentences are neither true nor false — as it is sometimes put, they are semantic gaps. The second is that according to which paradoxical sentences are both true and false — as it is sometimes put, they are semantic gluts (dialetheias). Calling the first of these a solution is, in fact, somewhat misleading: it is rather like calling an opening gambit a game of chess. For the solution runs into severe problems almost immediately, and so can be only the first of a series of (often ad hoc) moves made to defend the original weak opening. Nonetheless, the symmetry involved in the gap and glut solutions is obvious enough to make the comparison a natural one.

So begins the first of Locke's Two Treatises of Government. But this Englishman, gentleman, and self-styled ‘lover of liberty’ was not himself above pleading for slavery when it suited him. That plea has been an embarrassment to his admirers ever since. Locke attempted to legitimize slavery by portraying it as a form of punishment for crimes committed where no central political authority or justice system exists. If a victim of an assault is entitled to take his attacker's life in self-defense, Locke reasoned, he must also be entitled to take his attacker's liberty.

Descartes contends that he, or his mind, is really distinct from his body. Many philosophers have little patience with this claim. What could be more obvious than that the mind depends on the body? But their impatience often dissolves when they recognize that Descartes only asserts a de re modal statement. To say that one thing is really distinct from another is to say that each can exist apart from the other (AT VII 162: CSM II 114). But should we grant Descartes this de re modal claim itself?

Descartes's argument for the real distinction is based on the assumption that clear and distinct conception provides a reliable guide to possibility.

A tempting solution to problems of semantic vagueness and to the Liar Paradox is an appeal to truth-value gaps. It is tempting to say, for example, that, where Harry is a borderline case of bald, the sentence

1. (1) Harry is bald

is neither true nor false: it is in the ‘gap’ between these two values, and perhaps deserves a third truth-value. Similarly with the Liar Paradox. Consider the following Liar sentence:

1. (2) (2) is false.

That is, sentence (2) says of itself that it is false. If we accept the Tarskian schema

where ‘S’ is a name of a sentence ‘p,’ we are led into paradox. Both the assumption that (2) is true, and the assumption that (2) is false lead us, via (T), to

1. (3) (2) is true if and only if (2) is false.

Given this result, a natural reaction is to place (2) in a ‘gap’ between true and false.