McGinn and Cognitive Closure
McGinn suggests that we cannot understand how our conscious minds fit in with our brains:
I argue that the bond between the mind and the brain is a deep mystery. Moreover, it is an ultimate mystery, a mystery that human intelligence will never unravel. (McGinn 1999, p. 5)
We are cognitively closed off from understanding consciousness (McGinn 1989). We cannot answer all questions. Like all animals, we have cognitive limitations. Our understanding of consciousness might be analogous to that of dogs’ understanding of quantum mechanics.
Philosophers since Descartes have struggled with the understanding of consciousness in a physical world, and have gotten nowhere. It is time to give up the quest to explain consciousness. In McGinn’s view, human cognition is geared to understand a three-dimensional, spatial world, but consciousness is not there—it is outside space:
There is this strange incongruity in the relation between mind and world: the world outside us is essentially spatial and we represent it that way in our every experience, yet our experience is itself essentially nonspatial. It is as if to be aware of a spatial world the mind has to exist outside of space. (McGinn 1999, p. 111)
How could the mind exist outside space? The universe might have come from a big bang that determined the features of our universe, but remnants of a nonspatial reality before the big bang remain as consciousness.
It may sound as if McGinn is a dualist, but he sees himself as a mysterian property pluralist. In his view, reality has many properties—some explainable, some not. McGinn is suspicious of views that sum up reality in fixed ontological categories such as physicalism or dualism:
I am sometimes described as a mysterian physicalist, i.e., as someone who holds that there are unknowable physical properties of the brain. That, however, is not my position: I would not describe the unknowable properties of the brain that explain consciousness as “physical,” since I am suspicious of the whole notion of the physical. For the same reason, of course, I am not a dualist, if that means someone who believes that the mind is “nonphysical.” (McGinn 2004, p. 19)
McGinn accepts the ontology of neither the materialist nor the idealist because the mental and physical are ill-defined categories:
All such categories are ill-defined, as I see it. If anything, I am a mysterian property pluralist: I think there are many kinds of properties that pose various kinds of explanatory questions, some soluble, some not. (McGinn 2004, p. 19)
The notion of physical matter is unstable. Think of Descartes’s conception of body. He thought of its essence as an extension. Moreover, there was no empty space in the universe—only geometric shapes, pushing against each other. Newton’s conception of matter includes mass and gravitational attraction. In atomic theory, matter is mostly empty space. For Einstein, matter and energy are interchangeable—different aspects of the same underlying reality. With quantum mechanics, one particle can be in two states at the same time (superposition) and two particles can affect each other instantly over vast distances. Physicists also tell us that the universe consists mostly of dark matter that we know hardly anything about. One of the latest theories in physics—string theory—if true, would mean that our universe consists of vibrating strings. What holds the category of physical matter together? We simply explain different properties of reality as best we can. But consciousness depends on a property of the brain that we cannot know:
Consciousness is rooted in the brain via some natural property of brain tissue, but it is not explicable in terms of electrochemical processes of the familiar kind. I shall argue that it is the very unknowability of this property that generates all our perplexities. (McGinn 1999, p. 29)
Suppose McGinn is wrong and the solution to the problem of consciousness involves some nonmysterious causal factor of the brain. We assume that a property, P, is the cause of consciousness.
We should not think of consciousness as being outside the brain, as in the diagram above. But where could it be located? We can perhaps point to the brain and say that consciousness is in here somewhere; nevertheless, we don’t find consciousness entangled within its cells. Neuroscience explains the brain in increasing detail. But if consciousness is not found in the brain—like neurons, glia, cell nuclei, cortical regions or other brain structures—then how can we find out about P? How could we find what causes consciousness? The problem is not only that consciousness is unobservable in the brain. Many entities of physics are currently unobservable, but that does not hinder us from theorizing. Moreover, with new technology, they might become observable. This happened many times throughout history, as when scientists waited for the Large Hadron Collider to observe the Higgs boson.
To say that consciousness depends on an unobservable property implies something different from saying that an entity of physics is unobservable. In McGinn’s view, consciousness is not only practically undetectable but also absolutely undetectable (at least from a human point of view).
Let us examine the problem of consciousness the other way around to see if we can make better progress. We can observe consciousness in the first-person sense. But now we find ourselves with another problem. It is possible to monitor our conscious states—such as thoughts and feelings—but by doing so, we gain no access to the physical properties of the brain.
We cannot trace the causal arrow backward from within consciousness to P and find ourselves in a muddle. When we seek a causal path from brain to consciousness, we find nothing, and when we start with conscious experience and retrace a causal path in the other direction, we also find nothing.
-  This suggestion led to a heated debate with philosopher Daniel Dennett, who said it was embarrassing to be in the same field as McGinn and wrote a book, Consciousness Explained (Dennett1991), largely in response to McGinn, in which Dennett set out to explain consciousness.