This contention is close to that of Aristotle...

This contention is close to that of Aristotle; and Montesquieu is in many ways an Aristotelian thinker. But he stresses explicitly, in a way that Aristotle never does, the social milieu in which politics and morals have to be placed. He is the first moralist with a sociological perspective. (Vico precedes him as a sociologist, but is not in the same sense a moralist.) The types of society enumerated by Montesquieu are three: despotic, monarchical, and republican.

Each type has its own kind of health and its own characteristic ailments. Each is marked by a dominant ethos: despotisms by fear, monarchies by honor, republics by virtue. Montesquieu’s own moral preferences emerge in two ways: implicitly in his tone of voice, which betrays a modified admiration for republics, an approval of monarchy, and a genuine dislike of despotism; and explicitly in his repudiation of the attempt to state true moral precepts for all times and places.

“When Montezuma insisted that the religion of the Spaniards was good for their country and the Mexican for his own, what he said was not absurd.”50 Each society has its own standards and its own forms of justification. But from this it does follow that every form of justification which attempts to provide norms of a supracultural kind is bound to fail; hence Montesquieu without inconsistency could attack a variety of moral views as ill-founded.

More than this, Montesquieu combined with his relativism a belief in certain eternal norms, and it perhaps seems more difficult at this point in the argument to acquit him of inconsistency. We have, according to Montesquieu, a concept of justice at least which we can formulate independently of any existing legal system and in the light of which we can criticize all such systems. We can judge positive laws to be more or less just.

How can Montesquieu believe both that every society has its own standards and that, nonetheless, there are eternal norms by means of which such standards can be criticized? If we read Montesquieu as merely asserting that there are certain necessary conditions which any positive code of laws or rules must satisfy if it is to be called just, then he is not inconsistent in also asserting that what is held to be just must vary from society to society.

For although the same necessary conditions must be satisfied in all societies, the satisfaction of these conditions may in no society be sufficient to characterize an action, policy, or rule as just.