The idea of incommensurability

You might join the army or you might become a priest. Which would be better? Intuitively it seems this question may have no determinate answer; the values realized by these two careers seem to be so very different that they cannot be weighed against each other in a precise way. In some circumstances there will be a determinate answer to the question – for instance if you do not believe in God and like guns. But, in more balanced circumstances, it will not be determinate which is the better option. This phenomenon of indeterminacy is often called the ‘incommensurability’ of values. It is often thought to be a central feature of ethical life.

James Griffin has taken up the subject of incommensurability several times during his career. He is not enthusiastic about its importance, and even casts some doubt on its existence. He points out, first, that what many philosophers have called ‘incommensurability’ is not really that at all, or ought not to be called that. ‘Incommensurability’ ought to be reserved for cases where alternatives are ‘incomparable’ as Griffin puts it, by which he means that they cannot be put in an order. When a philosopher says the value of free speech is incommensurable with the pleasure of eating pizza, she means that free speech is immeasurably more valuable than this pleasure. That is to say, free speech and this pleasure can be ordered, emphatically. A small amount of free speech is better than any large amount of pizza-pleasure. This is not really incommensurability but extreme commensurability. Griffin mentions other misuses of the term too. If we set the misuses aside, and concentrate on true incommensurability, he thinks it may be hard to find any.