Kripke, Saul Aaron (1940–)

3. Necessity and essentialism

Essentialism is the view that things have certain of their significant properties necessarily – that they could not have existed without possessing those properties (see Essentialism). In the early 1960s the very notion of necessity was often thought to be incoherent. But even philosophers who granted the meaningfulness of the notion and conceded the existence of certain necessary truths typically found essentialism unacceptable.

Much of the antipathy towards necessity and essentialism may be traced to a confusion of necessity with analyticity (see Analyticity). Just as Kripke urged that a prioricity and necessity are distinct notions, so did he insist that analyticity is a third notion, not to be confused with the others. But such a confusion appears to underlie one of the main arguments against essentialism. It was claimed that the idea that a thing has a property necessarily makes no sense absolutely, but only relative to a specific way of designating the thing. For example, if the number nine is designated by ‘the number of the planets’, then it has the property of numbering the planets necessarily, but if it is designated by ‘nine’, it does not. So the idea of attributing a necessary property to the object independently of any designation makes no sense (see Quine, W.V.).

This may seem correct if we have not carefully distinguished necessity from analyticity. For ‘The number of the planets numbers the planets’ seems analytic while ‘Nine numbers the planets’ does not. But when we set aside analyticity and focus clearly on necessity, the question no longer concerns sentences of our language. Instead we are asking whether a certain object had to have a certain property. If the object is the number nine and the property is numbering the planets, the answer must be ‘no’, for we can imagine a world in which the solar system developed differently. And if the property is being a square, the answer must be yes. There is no world in which nine is not a square. (Of course it could be that the name ‘nine’ did not refer to nine. But, in such a world, nine – whatever it might be called there – would still be a square.)

Kripke argued that ordinary entities also have nontrivial essential properties. Suppose a specific table, T, is made of wood. According to Kripke, although it is possible for tables to be made of other materials, no such possibility exists for T. Of course it is an empirical matter whether T has this property at all. But this merely means the matter is a posteriori, not that it is contingent. We know that such properties as T’s location or finish are contingent because we can imagine a world in which T is somewhere else or differently finished. According to Kripke, we cannot imagine a world in which T is not made of wood. When we think we have imagined such a world, closer consideration reveals it is really a world in which some other table has been switched with T (or made instead of T, and so on).

Kripke relies heavily on ‘intuition’ here and in his other philosophical work. But he is not invoking a special power or sense. Rather, he is insisting that the concepts that concern us in philosophy are, after all, our own concepts, and accordingly that the best evidence for how they fit together can only come from thinking as carefully as we can about them. In this entry we have managed a glimpse at some of the results of this approach in Kripke’s work on reference and modality. Comparably powerful and compelling results are to be found throughout the full range of his remarkable work.