Who should care about the relation of brain and mind?  The right answer may be: everybody, not just neuroscientists or philosophers specializing in the mind-body problem.  In one of his brilliant thought-experiments Ludwig Wittgenstein imagined that some group of people could perceive the workings of another person's nervous system and that they would use these perceptions in their behavior toward others.  Wittgenstein's point is that this would not affect only their factual knowledge but also the ways in which they speak and think of other people.  The concepts they apply to others, like the concept of pain, Wittgenstein says, would be different from ours, although not unrelated to them.  "Their life would look different from ours."

The tremendous development of brain imaging techniques is beginning to turn Wittgenstein's thought-experiment into reality, perhaps at first for the group of people called neuroscientists, if not yet for us ordinary folk.  Is it producing the results Wittgenstein envisaged?  Yes, at least in the sense that we need new concepts for the purpose of interpreting what neuroscientists now can see.  Old mentalistic concepts about what can happen in one's mind are of little help in understanding the happenings we can literally see taking place in another person's brain.

Wittgenstein is right in that this difficult problem is relevant also to the concerns of philosophers and psychologists.  Philosophers, because these developments affect our ways of conceptualizing other people's minds.  Psychologists, because they have to use these conceptualizations in their work.  Neuroscientists themselves are affected, because they have to use the new conceptualizations in speaking of the functional manifestations of the neuroscientific phenomena they are studying.  They have to find out, not only the etiology of autism or  the deficiency of the man who mistook his wife for a hat, but also what is conceptually speaking wrong with such patients.  A satisfactory explanation of a mental phenomenon, even when this phenomenon is approached purely functionally must involve an identification of this phenomenon.

Wittgenstein suggests that a new kind of perceptual opacity would change even the look of ordinary people's life.  This is not happening, at least not yet.  But perhaps it might be illuminating and clarifying to think seriously what might be involved in such a change.  In Paul Ziff's old joke, a behaviorist greets another one by saying "You feel fine this morning.   How do I feel?"   Should we perhaps begin by telling this joke about neuroscientists rather than behaviorists?