David Chalmers on Consciousness
Chalmers assumes consciousness involves both experiential and nonexperiential aspects. On the basis of this assumption, he finds two different classes of problems of consciousness:
There is not just one problem of consciousness. “Consciousness” is an ambiguous term that refers to many different phenomena. Each of these phenomena needs to be explained, but some are easier to explain than others. At the start, it is useful to divide the associated problems of consciousness into “hard” and “easy” problems. (Chalmers 1995a, p. 9)
The easy problems are nonexperiential and have functionalist solutions:
The easy problems are easy precisely because they concern the explanation of cognitive abilities and functions. To explain a cognitive function, we need only specify a mechanism that can perform the function. The methods of cognitive science are well suited for this sort of explanation and so are well suited to the easy problems of consciousness. (Chalmers 1995a, p. 11)
But the hard problem of explaining experience has no functionalist explanation:
By contrast, the hard problem is hard precisely because it is not a problem about the performance of functions. The problem persists even when the performance of all of the relevant functions is explained. (Chalmers 1995a, p. 11)
Chalmers catalogs approaches to the hard problem: denying its existence; avoiding it (explaining the easy problems instead); and searching for neural correlates of consciousness. These approaches do not inspire Chalmers. Many believe that the work on neural correlates will eventually yield a complete causal theory of consciousness. Chalmers thinks not. He concurs with Leibniz that experience is inexplicable as physical mechanisms. Leibniz imagined himself shrunken and entering a brain. All he would see would be mechanisms in a device similar to a complex clock or mill—not a mind with experiences. How could he understand experience in terms of causal mechanisms? Experience and mechanisms seem utterly different. Similarly, Chalmers does not see how neural mechanisms could cause experiences:
The question about experience here is as mysterious as ever. The point is even clearer for new discoveries in neurophysiology. These discoveries may help us make significant progress in understanding brain function, but for any neural process we isolate, the same question will always arise. (Chalmers 2010, p. 14)
The brain consists of neurally decomposable cognitive functions lacking a phenomenal glow:
It is difficult to imagine what a proponent of new neurophysiology expects to happen over and above the explanation of further cognitive functions. It is not as if we will suddenly discover a phenomenal glow inside a neuron! (Chalmers 1995a, p. 17)
Both Leibniz and Chalmers think of the brain as lacking causal powers of experience. They don’t think that anything physical can cause an experience.
To support his noncausal position on experience, Chalmers entertains the thought of nonconscious creatures who behave like us. He imagines a world like ours, minus consciousness—we’ll call it World Two. World Two has type-identical physical entities and natural laws. It is a mirror world.
If consciousness is a physical phenomenon, World Two would be inconceivable: given type-identical physical entities and natural laws, consciousness must be present. Chalmers suggests, however, that World Two is conceivable, and he takes it as evidence that consciousness is nonphysical.