As commonly understood Kripke’s notion of rigidity is a property that some terms have and that others lack. I argue that there is no such property that is had by some terms and lacked by others; hence there is no rigidity as commonly construed . Recent discussions of rigidity have, I claim, forgotten the importance that stipulation plays in Kripke’s original account. In short the argument is that the truth-conditions of sentences with supposed rigid designators in them can vary depending on the stipulative act of the speaker. But if rigidity were a property of the terms themselves the truth-conditions should not vary! I introduce the notion of frigidity which is not a property that terms have, but something that we do and is a tool that we use to evaluate counter-factuals (Introducing Frigidity). We decide to ‘freeze’ the referent of a term and then try to evaluate counter-factual statements in terms of the constant referent. The ‘freezing’ is accomplished by a stipulative act on the part of the speaker.
Thus it follows that there are two ways to perform the thought experiment of frigid stipulation corresponding to taking one or the other terms flanking the identity sign as frigid and asking ‘what about that in another possible world?’ We decide that we are going to stipulate, trivially as Kripke says, that we want to find out about X in a possible world. So for water=H20 we can ask ‘what if H20, this very chemical substance, was in a world that was different from ours?’ If it turns out that H20 is not ‘watery’ that is OK. We can then also ask ‘what about water? Stuff that acts like this, fills our lakes and etc? What if we found a world that had watery stuff that was not H20?’ And that is OK as well. This has the advantage of explaining why people’s intitions vary about whether twater is water.
However Kripke (Kripke 1980) makes the claim that when it comes to mental kinds we cannot do this because in the case of pains and whatnot their properties are not separable in this way. But once we switch from rigidity to frigidity this is less obvious. We can hold the brain state frigid and ask ‘what is it like to have this brain state in a world that is different from ours?’ It may turn out that that very brain state is not like anything to have at all. On the other hand we can hold the sensation of pain frigid and ask questions about worlds with that sensation. It certainly seems logically possible that some of those worlds will have that sensation and yet not have any brain states at all!
This is just what Kripke’s bjection to the identity theory is. He says “this notion seems to me self-evidently absurd. It amounts to the view that the very pain I now have could have existed without being a mental state at all,” (p.147). Well, yes this is true if what he means is that the very brain state he is in and which is his pain might have existed but was not painful for the creature that had it. This is to do no more than admit that there might exist an unfelt pain. He is wrong if he means that a pained creature, one that felt pain, would not be in pain.