Ned Block and the Concept of Consciousness
Ned Block argues that the word “consciousness” has different meanings we must get clear about (Block 1995). His argument is similar to that made by the philosopher Wittgenstein: whenever we are dealing with a noun, we tend to think it refers to something specific. But as Wittgenstein points out, a single noun may refer to many things.
Access and Phenomenal Consciousness
Block asks us to consider consciousness as a mongrel concept: it has different meanings. Phenomenal consciousness is, according to Block, about experiences. My phenomenal consciousness of writing in a beach house encompasses the smell of ocean air, the sounds of rolling waves, glittering sunlight, and the taste of freshly made coffee. Phenomenal consciousness is what we normally think of as experience with all of its impressions and sensations.
Block contrasts phenomenal consciousness with access consciousness—having access to information. If we think of consciousness as Block does, then it looks as if some misunderstandings can be avoided. For example, the functionalist approach of cognitive science is not threatened by those who argue that it cannot explain consciousness. A functionalist approach may be unable to explain phenomenal consciousness, but it could explain access consciousness. Block is a functionalist when it comes to access consciousness. We can think of the brain as a functionalist machine with access consciousness through information processing. But phenomenal consciousness does not reduce to functionalist information processing.
Blindsight as Access Consciousness
To support his division between phenomenal and access consciousness, Block asks us to consider blindsight. As mentioned in chapters “Consciousness Rediscovered” and “Consciousness as a Modern Mystery”, if you are a blindsighter, your primary visual cortex is impaired, so you have a blind area in your visual field. In Block’s words, you have no phenomenal consciousness of things in your blind area. I hold up a cross there and ask you what you see. You see nothing. Yet if I ask you to guess what is in front of you or how the object is rotated, your guesses are better than chance. What does this mean? It appears that your brain has access to information about your left visual field although you have no experience of seeing anything there. Block takes this as evidence for access consciousness—your brain has conscious access to information without phenomenal consciousness.
If Block is right about access consciousness, does it mean my pocket calculator is conscious? According to a functionalist account, the calculator does have access to information. The same goes for microwave ovens, remote controls, and hundreds of gadgets found in a typical household. It is difficult to see what entities could not be construed as having access consciousness. But what sense does it make to speak of nonsentient things that are incapable of having any point of view—in Nagel’s sense, incapable of any subjective experiences whatsoever—as being conscious? Block must explain further how access consciousness is more than a convenient construct that fits with functionalist models of cognitive science.