# The Mind/Brain Identity Theory:

A Critical Appraisal

## 5. Conclusion

In this essay, I have outlined what I consider to be the outstanding difficulties for a materialist version of the identity theory. I began with a consideration of the application of the law of indiscernibility of identicals to phenomenal properties, as this application constitutes a problem for the theory. In showing how an identity theorist may dispose of this objection, I led the discussion into a consideration of the problem of phenomenal qualities. My aim here was to show that in attempting to solve this problem, the identity theorist is faced with two horns of a dilemma. Either he abandons all hope of demonstrating his thesis to be true in the near future, barring a revolution in physics just over the horizon, or he flirts with an irreducible dualism of types. Although the identity theory has some significant advantages over its non-interactionist rivals, epiphenomenalism and psycho-physical parallelism, it is caught somewhat between a rock and a hard place. It is unclear which is the least unpalatable of the alternatives. Perhaps further analysis will reveal one or both horns of the dilemma to be imaginary.

One thing that I have stressed throughout this essay is the necessity of evaluating mind-body theories in their historical context. This is because there is no decisive, once and for all, refutation of any of the current mind-body theories. In this vein, I have considered objections to the identity theory that are not logically decisive, but which should give us reason to pause and consider its problems.

There are other challenges for the theory that I think are important, but less significant than the ones that I have considered here. The doubt concerning the one-to-one identity relationship between mental states and brain states is such a problem. Another problem that I have not considered is the charge of speciesism. I have not discussed these objections here because I think that they can be accommodated on a revised identity theory. On such a revised version of the theory, I think some version of a type-type identity can be salvaged. Also, the charge of speciesism can be deflected by rendering the form of the identity relation open-ended. Such modifications to the theory, of course, leave revisionist identity theorists open to the charge of *ad hoc*ness. But that is another story.