Problem of Other Minds

The problem of other minds has traditionally been regarded as an epistemological challenge raised by the skeptic. The challenge may be expressed as follows: given that I can only observe the behavior of others, how can I know that others have minds? The thought behind the question is that no matter how sophisticated someone's behavior is, behavior on its own is not sufficient to guarantee the presence of mentality. It remains possible, for example, that other people are actually nothing more than automata made out of flesh (or "philosophical zombies" as the term for this example stands). Perhaps the main argument offered against this possibility in the history of philosophy is the argument from analogy (other things have minds if they are sufficiently similar to us); it can be found in the works of John Stuart Mill, A. J. Ayer, and Bertrand Russell. The argument from analogy has faced scrutiny from the likes of Norman Malcolm who have issues with the 'one case' nature of the argument.

More recently, it has come to be appreciated that the epistemological issue is intimately related to metaphysical and conceptual issues. This is best appreciated by considering the examples of type physicalism and philosophical behaviorism. According to the type physicalist, to be in a certain type of mental state is just to be in a certain type of physical brain state. So, if we can detect that another individual is in a certain type of physical state, then we can know that they are in a certain type of mental state. Thus, it seems that we can know, in a relatively unproblematic way, that other people are in certain mental states. In this case, the epistemological problem is dissolved by making a claim about the metaphysics of mind. Logical behaviorism, on the other hand, makes a claim about the nature of our mental concepts. This claim is that statements about mental phenomena can be analyzed into statements about behavior and behavioral dispositions. To be in a certain mental state, e.g. pain, is just to behave, or be disposed to behave, in certain ways. Since statements ascribing mental predicates to individuals make claims about nothing over and above their behavior, they can be verified to be true or false by observation of behavior. Thus, the behaviorist closes the conceptual gap between behavior and mentality which is responsible for the epistemological problem.