He is best known for his attack on the descriptivist (Fregean, Russellian) theory of reference with respect to proper names, according to which a name refers to an object by virtue of the name’s being associated with a description that the object in turn satisfies. He gave several examples purporting to render descriptivism implausible.
The key features of Kripke’s contribution to the philosophy of language are (1) his account of names as rigid designators and not clusters of definite descriptions; and (2) his view that there are necessary a posteriori and contingent a priori truths. Both these claims are contentious and continue to be debated vigorously.
In ‘Naming and Necessity’ Saul Kripke argues against type-type-identity theory by the use of an argument from philosophy of language.
Kripke wants to demonstrate that if one believes in the identity of mental- and brain states, one needs to accept the theory’s full consequence, namely that there cannot be brain states which are not mental states or vice versa. To defend identity theory one would thus be in a need to prove not only empirical (e.g. by scientific research), but analytical a priori, that neither brain states without mental states, nor mental states without brain states could exist. This is quite hard, if not impossible, to do since on the one hand mental states are intuitively independent from the physical domain (Cartesian intuition) and on the other hand zombies are conceivable.
Kripke introduces two types of designators (namings) of entities, namely rigid designators and non-rigid (flaccid) designators. Rigid designators refer to the same entity in every possible world, if the designator has any reference at all. For example, the rigid designator ‘Anthony Flemming’ refers to the same entity in all conceivable worlds. Flaccid designators may refer to different entities in different possible worlds. For example, ‘the author of this essay is Anthony Flemming’ only in this very world. Flaccid designators refer to entities only by use of contingent properties (e.g. X is the author of this essay).
Identities between two rigid designators that name the same entity are necessary. The proposition that they are identical is trivially a priori true (you do not need any experience to prove it). If not both designators that are claimed to be identical are rigid, this identity is contingent, if it is true. The identity might be true in this world, but this has to be proven empirically since one could conceive a non-rigid designator referring to some other object.
Kripke’s strategy is to show, that identity theorists could not argue mind-brain-state identity to be a contingent identity. He demonstrates that both, the term ‘mental state’ and the term ‘brain state’ that are claimed to refer to one and the same entity are rigid designators. As an example Kripke uses the proposition ‘pain is c-fiber stimulation’. The term pain is a rigid designator because you could not imagine it to refer to something else than the sensation pain in another world. According to Kripke one could transfer this example to every other mental-state and the brain state, which is said to be identical with it.
Identity theorists have asserted, the mental states are ‘brain states identity’ was contingent just like the ‘heat is molecular movement’ identity is contingent. Kripke replies, even the latter identity was not a contingent one at all, but necessary. It only seems to be contingent, for one confuses the physical property heat with the sensation of feeling heat. But the name heat could either mean the one or the other thing, since the physical property heat is not identical with the sensation heat (There is heat, namely molecular movement, when there is nobody to perceive the sensation caused by it). If the designator heat names the physical property, it is a rigid designator and the identity is necessary. If the term heat names the feeling there is no identity at all.
Eventually Kripke reasons from this, that type-type-identity has to be necessary, if true, which connotes that every mental state is identical with a specific brain state in every conceivable world. But mental states without brain states and brain states, that are not mental states, either the conception or identity theory has to be false.
Kripke’s argument seems to be some sleight of hand at first glance, because it is that astoundingly convincing and still it seems at least imaginable that mental processes are really brain processes and nothing over and above in this world. This might just be, because he does not have any idea how to solve the mind-body problem himself. Moreover Kripke’s argument is a very strong one indeed. It is very difficult to defeat because its core structure is logically sound:
If it is:
a) true that the terms for both mental- and brain-states are rigid designators, and
b) they are identical, then
c) the identity has to be necessary.
The only way to attack the argument is to challenge the framework of semantics it makes use of. The excerpts contain less information on this topic. Important questions would be for example: Which contingent identities could we know a priori, if any? Is a possible world really identical with a conceivable world and what does this denote to rigid designators?
It is obvious that this is too far-reaching to be examined in this paper.
Kripke is a peculiar man with a sharp intellect. He talks fast and he thinks perhaps even faster. One is still stricken by the fact that he does not seem vitally concerned about applying philosophy to social issues. His ideals do not seem to be those of the visionary public intellectual, like Sartre, Russell, Chomsky or Cornel West. Kripke is one of America’s most respected philosophers, still he is not significant in public debates. For many he is a living legend.