The Mind Problem
What makes body possible? What are the conditions of the possibility of material objects? Space: bodies are essentially extended things and space is the home of extended things. Without space body would be impossible; with it body slots smoothly into place. Space and body are intelligibly connected, made for each other. A world consisting of space and bodies in space is an intelligible and possible world, not a peculiar and paradoxical one. For instance, parts of bodies, even minute parts, map neatly onto parts of space. The two seem designed to fit together. An intelligent God would approve. But now ask what makes mind possible: what are the conditions of possibility for minds to exist? Minds are not extended things but rather conscious things: their essence is thought (as Descartes put it) not extension. So space is not the matrix into which they naturally fit—its properties do not map onto the properties of mind. Parts of consciousness don’t match up with parts of space; the very idea seems like a category mistake. So what does make mind possible? That is the problem I am calling “the mind problem”.
One response is to invoke a different type of underlying reality: instead of extended space we introduce a non-spatial substance or realm. Call this “immaterial substance”; then we say that what makes mind possible is the existence of an immaterial substance. But this has all the advantages of theft over honest toil, for we can say nothing about the properties of this supposed substance that explains its link to mind. Space has a nature ideally suited to matter, but the supposed non-spatial substance has no nature that we can specify, and so no nature that can explain its power of harboring consciousness. We are merely bandying labels and conjuring phantasms. So this kind of dualism does not solve the mind problem; it simply re-raises it. We still don’t know what gives mind an intelligible foothold in the world. Postulate an immaterial substance if you will, but don’t fool yourself into thinking you have solved anything thereby. For instance, how does the what-it’s-like of consciousness arise from the inner nature of the immaterial substance? Have you really any idea what you are talking about when you utter these words?
Another response is to populate the world with something closer to mind so as to give mind a chance of getting off the ground. Thus we postulate a world of mini minds that can organize into a recognizable macro mind. We call this “panpsychism” and congratulate ourselves on our ingenuity. Now we can map parts to parts, starting with something that will in principle make mind possible, viz. more mind. Here the problem is that the mini minds raise the same question as the macro mind: what makes them possible? They need to slot into the world of extended matter (specifically, the brain), but we have said nothing about how that works; and there is the distinct danger that we will end up declaring them primitive and inexplicable, in which case why not do that to begin with and avoid the detour through the mini mind level? What we don’t have is an analogue of the role of space in relation to matter; instead we have the analogue of postulating lots of mini bodies to explain the existence of macro bodies—but what makes them possible? We already know that space exists, so we can help ourselves to its properties in accounting for the possibility of matter. But in the case of mind we have no such antecedently accepted reality to fall back on.
This is where we might choose to rethink our premises: why not deny that mind lacks extension? True, it seems that way intuitively, but intuitions can be faulty, so we are not obliged to follow their dictates—leaving us the option of asserting that consciousness is an extended thing just like matter. Thoughts and feelings accordingly have length, breadth, and height, size and shape, location and volume—they are no different from regular chunks of matter. Then we have no trouble saying what makes them possible—the same thing that makes bodies possible. We label this liberating doctrine “materialism” and commend ourselves for our intellectual fearlessness in the face of insurmountable paradox. The drawback is that this looks a lot like denying the obvious in order to escape a genuine difficulty: mind simply does not have extension, no way no how. That is like saying that numbers have mass or values have color! What is the exact size of the thought that purity is overvalued? Where are that thought’s parts located? Do some thoughts have different shapes from other thoughts or do they all have the same shape (different from the shape of desires)? Such questions haunt (and daunt) less robust souls than our intrepid materialist.
Have we run out of options? Stunned into silence, another type of theorist wonders if we are able to say anything: perhaps the answer to our question lies beyond our limited powers of comprehension. The conjecture is that in addition to properties of extension material things have other properties of an unknown nature that explain the possibility of mind. These properties are intuitively “closer” to mind than properties of extension, which is just physical geometry. Thus mind comes to exist in virtue of hidden properties of matter, though properties as natural as any known properties. If a race of beings had no notion of space, then they might puzzle over how bodies can exist; we are like that with respect to mind. In reaction to this “mysterian” position many feel that we simply haven’t the foggiest idea what these hidden properties could be, so they doubt that such a view is tenable. Yet the other positions are even less tenable, so we seem stuck in theoretical limbo. The mind problem continues to taunt us.
What is called the mind-body problem could be re-labeled the mind problem, because it concerns the very existence of mind not just its relation to body. It is not that we understand how mind exists and we understand how body exists but we are puzzled about their connection; we don’t really understand how mind exists at all. It exists in virtue of something—something must make it possible—but we draw a blank on saying what it might be. Descartes’ problem goes deeper than even he realized.
 I am not claiming to have decisively refuted the various positions that have been offered in this area in these brief remarks; I am merely summarizing prevailing opinion, or recording familiar objections. I am aiming to articulate the shape of the debate.
 Someone might wonder whether time is to mind as space is to body: does mind exist in virtue of time? It is true that consciousness has a temporal dimension, while lacking a spatial dimension, and this seems integral to its essence. Certainly this would restore the analogy to matter and space, but time by itself cannot explain the distinctive features of mind, since it holds equally of non-conscious phenomena. It is not that the features of consciousness map point-by-point onto the structure of time; time is too “thin” to provide this kind of underpinning. Still, the suggestion is worth pondering (could time have a richer nature than we generally recognize?).
 Another way to put the point is that mind presents itself as a dependent phenomenon but it is impossible to say what it depends on: it is unintelligibly dependent. The threat is that this epistemic point could turn into metaphysical impossibility. Then we end up denying its very existence.