### Kripke's Naming and Necessity

Posted:

**Wed Feb 13, 2019 12:18 am**I will break Kripke's main ideas down one at a time and see if anyone is interested in discussing them.

First, the modal problem. Most philosophers would agree that x=x is a necessary truth. The question is, given that y=x, does it follow that y necessarily equals x? It does seem to follow directly from the first identity by the rule of substitution. Let 'x necessarily equals x' be written #(x=x). Since we assume that x=y, we just substitute y for x and get #(x=y). So it would seem necessary that, if x=y, then #(x=y).

However, there seems to be a problem here. Some identity statements seem to be contingent and not necessary at all. Example - Venus can be seen in the morning in one location and then at night in another. Before modern times, it was thought that these two bright objects in the sky were two different stars. The one was called the morning star and the other the evening star. The Greeks (or some ancient peoples) called the former Phosphorus and the latter Hesperus.

Now we know that Hesperus=Phosphorus (and both are just Venus) is a true statement. Given what we said above about the necessity of identity statements, it must then be necessary that Hesperus=Phosphorus (or #(Hesperus=Phosphorus)). However, as Quine and others pointed out, such identity statements are contingent and not necessary. For it was only after the empirical discovery that both were in fact Venus that we came to know the identity statement was true.

Kripke goes on to attempt a solution to this problem which, after a lengthy and groundbreaking analysis, eventually leads to an interesting take on the mind/body problem.

First, the modal problem. Most philosophers would agree that x=x is a necessary truth. The question is, given that y=x, does it follow that y necessarily equals x? It does seem to follow directly from the first identity by the rule of substitution. Let 'x necessarily equals x' be written #(x=x). Since we assume that x=y, we just substitute y for x and get #(x=y). So it would seem necessary that, if x=y, then #(x=y).

However, there seems to be a problem here. Some identity statements seem to be contingent and not necessary at all. Example - Venus can be seen in the morning in one location and then at night in another. Before modern times, it was thought that these two bright objects in the sky were two different stars. The one was called the morning star and the other the evening star. The Greeks (or some ancient peoples) called the former Phosphorus and the latter Hesperus.

Now we know that Hesperus=Phosphorus (and both are just Venus) is a true statement. Given what we said above about the necessity of identity statements, it must then be necessary that Hesperus=Phosphorus (or #(Hesperus=Phosphorus)). However, as Quine and others pointed out, such identity statements are contingent and not necessary. For it was only after the empirical discovery that both were in fact Venus that we came to know the identity statement was true.

Kripke goes on to attempt a solution to this problem which, after a lengthy and groundbreaking analysis, eventually leads to an interesting take on the mind/body problem.