Consciousness: What We Still Don’t Know


Much has recently been written about the subject of consciousness, thanks to the revival of interest in disciplines as various as philosophy, psychology, cognitive science, and neurobiology. Of these various fields of research the one that I think is most likely to have important long-term results is neurobiology, where the race to solve the problem of consciousness is now on.

What exactly is the problem and how exactly do we suppose we can solve it? Our ultimate scientific objective is to find out how exactly the brain causes all of our conscious states and where and how exactly those states exist and function in the brain. I cannot overstate the importance of this project. If we had a full theory of exactly how subjective states of consciousness come into existence and function as parts of the real world it would be one of the most stunning scientific achievements of all time. Why can’t the brain scientists answer this question? It sounds like a standard scientific problem. Finding a causal basis of consciousness in the brain sounds no more mysterious than finding the causal basis of disease, inherited traits, or any other biological phenomenon. It turns out however that it is extremely difficult to do.

Part of the difficulty stems from the sheer technical problems of studying a system of a hundred billion or so neurons stuffed into the skull. But there are also some conceptual or philosophical obstacles. I used to think that philosophers should clear the ground so that we can get a clear statement of the problem and then get out of the way and let the neuroscientists take over and solve the problem. I still think that is exactly what should happen, but it turns out that the neuroscientists have been brought up on the same mistakes as the rest of us and these can stand in the way of the investigation.

First of all we have to get clear about what consciousness is. It is sometimes said that consciousness is “hard to define.” But if we are just talking about a definition that identifies the target of our research, rather than giving a scientific analysis of the sort that typically comes at the end of an investigation, it does not seem to me that consciousness is hard to define. Consciousness consists of states of awareness or sentience or feeling. These typically begin in the morning when you wake up from a dreamless sleep and go on all day until you go to sleep or otherwise become “unconscious.” According to this definition dreams are a form of consciousness. Self-consciousness, in the sense of having a second-order consciousness about your own consciousness, for example worrying (second order) about your pain (first order), is not required as part of the definition of consciousness, though for human beings it is quite common.

Some of the salient features of consciousness so defined are these: All conscious states are qualitative in the sense that there is something that it feels like,…

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