Online research in philosophy

Abstract Thomas Polger has argued in favour of the mind?brain type?identity theory, the view that mental states or processes are type?identical to states of the central nervous system. Acknowledging that the type?materialist must respond to Kripke?s modal anti?materialist argument, Polger insists that Kripke?s argument rests on dubious assumptions concerning the identity conditions of brain states. In brief, Polger claims that one knows that x and y are non?identical when one knows the identity conditions for both x and y. Replace x and y with ?brain states? and ?sensations? and it follows that one can know that brain states and sensations are non?identical only if one knows the identity conditions for brain states. But according to Polger, we do not know the identity conditions for brain states. Hence, we should not be so confident that brain states and sensations are non?identical after all. But Polger?s account is terribly flawed. Ironically, if Polger?s scepticism is warranted, then Polger himself has no good reasons to be a type?materialist. But more importantly, Polger?s scepticism regarding the identity conditions of brain states is deeply defective. We do, I submit, understand the identity conditions of brain states. In the end, I submit, Kripke is safe from Polger.

Although it seems plausible to say that the same story can be retold in different media, it is difficult to say exactly what this would entail. The primary difficulty is in coming up with an acceptable theory of story identity. In this article I present several theories of story identity and explore their weaknesses. I argue that in the end we are left with two unattractive options: a strict theory that implies that the same story can almost never be retold and a lenient theory that has trouble differentiating between a general story type and the same story.

One of the positive arguments for the type-identity theory of mental states is an inference-to-the-best-explanation (IBE) argument, which purports to show that type-identity theory is likely true since it is the best explanation for the correlations between mental states and brain states that we find in the neurosciences. But given the methods of neuroscience, there are other relations besides identity that can explain such correlations. I illustrate some of these relations by examining the literature on the function of the hypothalamus and its correlation with sensations of thirst. Given that there are relations besides identity that can explain such correlations, the type-identity theorist is left with a dilemma: either the correlations we consider are weak, in which case we do not have an IBE to an identity claim, or else the correlations we look at are maximally strong, in which case there are too few cases for the inductive part of the strategy to work.

It is commonly believed that there is a fundamental incompatibility between multiple realization and type identity in the philosophy of mind. This claim can be challenged, however, since a single neural type may be realized by different microphysical types. In this case, the identity statement would connect the psychological and the neural type, while the neural type, in turn, could be multiply realized by different microphysical types. Such a multiple realization of higher level types occurs quite frequently even within physics and it should be acceptable for physicalism in general.

Functionalism cannot accommodate the possibility of mad pain—pain whose causes and effects diverge from those of the pain causal role. This is because what it is to be in pain according to functionalism is simply to be in a state that occupies the pain role. And the identity theory cannot accommodate the possibility of Martian pain—pain whose physical realization is foot-cavity inflation rather than C-fibre activation (or whatever physiological state occupies the pain-role in normal humans). After all, what it is to be in pain according to the identity theory is to be in whatever state that occupies the pain role for us.

Functionalists in philosophy of mind traditionally raise two major arguments against the type identity theory: (1) psychological states are _multiply realizable_ so that there are no one-to-one mappings of psychological states onto neural states and (2) the most that evidence could ever establish is the _correlation_ of psychological and neural states, not their identity. We defend a variant on the traditional type identity theory which we call _heuristic identity theory_ (HIT) against both of these objections. Drawing its inspiration from scientific practice, heuristic identity theory construes identity claims as hypotheses that guide subsequent inquiry, not as conclusions of the research.