Other Minds and the Mind-Body Problem

Other Minds and the Mind-Body Problem

It is generally assumed that we have no problem knowing the existence and contents of our own mind, but we do have a problem knowing the existence and contents of other people’s minds. But it is a further question whether this is a necessary truth. I will argue that it is not: it is only a contingent truth that we know our own mind so well and other minds so poorly. This is not hard to see. We know our own mind by introspection, by “looking inward” (whatever that may be), but what if that faculty were to fail us? The faculty of sight may fail us, resulting in a drastic reduction to knowledge of the external world, so why not the faculty of introspection? Granted, cases of introspective blindness are not common—indeed, I have never heard of one—but the idea is not logically excluded. The right kind of brain damage could make it happen—just knock out the relevant neurons. Then the person would be unable to peer within and deliver a judgment about his mental state. You might have a mental state and not know it, these being distinct achievements. You could become self-blind; you have no consciousness of your mind. Yet you may retain your ability to infer your mind from other facts about yourself—behavioral and cerebral. Then you would be in the same position respect to your own mind as you are with respect to the minds of others. You would have a “my mind” problem. Maybe creatures could have evolved that are born this way: they have no introspective faculty but can make indirect inferences about their mental state. So, it is not a necessary truth that creatures with minds have no own mind problem; in some possible worlds there are minds that are not transparent to their owners. Isn’t this already partially true of us, what with the unconscious and self-deception and generally fallibility? Some people may be said to have giant own mind problems.

What about other minds—are they necessarily subject to skepticism? Here the problem can be circumvented by brain splicing: if brains are suitably connected, you could know what is in someone else’s mind.[1] This need not be done by surgical transplant but by remote communication: establish a link between my mind and yours such that what happens in your brain is fed directly into my brain’s introspective faculty. People could hook up this way, thereby gaining non-inferential knowledge of each other’s states of mind. They don’t need to infer other minds from behavior or by looking at the brain. People might even be born this way in some possible world. Imagine if self-blindness occurred simultaneously with other-vision: we would have a world with no problem of other minds, but a problem of one’s own mind—an inverted epistemic world. We live in a world with the converse problem, but it is not so in all worlds. The current set-up is therefore contingent.

How does the mind-body problem fit into all this? As follows: if we had the solution to that problem, we would have an alternative way to gain knowledge of minds—not introspective, not inferential, and not by splicing (or some equivalent). That is, we could deduce minds from whatever underlies them in the brain (or elsewhere): we would have a necessary link between the brain and the mind. Call this link L; then knowledge of L would provide knowledge of mind. The reason we can’t (without splicing) solve the problem of other minds is that we don’t know the identity of L—so we must go by behavior and observation of the brain (which doesn’t cover L). The same applies in the hypothetical case of self-blindness: we can’t replace the introspective faculty with knowledge of the necessitating link. We are ignorant of L, so we can’t use it to get around the other minds problem or the own mind problem (if we are afflicted by it). The other minds problem thus intersects with the mind-body problem. There are several ways in which we can in principle know minds: by introspection, by inference from behavior (including the brain’s behavior), by splicing (or some equivalent), or by solving the mind-body problem. In the actual world we have just two ways, but this is a contingent fact. In a world in which people have all four methods, they have no other minds problem or own mind problem. They are epistemically rich while we are poor. We are just a few possible worlds away from having no other minds problem at all. We could in principle be in receipt of data from three separate channels: via splicing, behavioral, and by solving the mind-body problem. This is the context in which to consider the other minds problem as we experience it.[2]

[1] See my “How to Solve the Problem of Other Minds”.

[2] Of course, if we can’t solve the mind-body problem, this is not a possible way for us to solve the other minds problem—not without radically changing our nature anyway. But other types of minds might not be thus ignorant, in which case the other minds problem may never have occurred to them. We just happen to have an other minds problem. The same is not true of the external world problem.