Joseph Levine’s Explanatory Gap
Early on, the philosopher Joseph Levine (1952—) articulated why scientific explanations of consciousness are problematic (Levine 1983). Levine credits British philosopher John Locke (1632-1704) for having understood the key issue in his reflections on how experience (simple ideas) bears no intelligible relation to corpuscular (physical) processes:
He states that the simple ideas which we experience in response to impingements from the external world bear no intelligible relation to the corpuscular processes underlying impingement and response. Rather, the two sets of phenomena—corpuscular processes and simple ideas—are stuck together in an arbitrary manner. (Levine 1983, p. 359)
Levine points out that Locke had to rely on God to make sense of how experience systematically accompanies physical processes:
The simple ideas go with their respective corpuscular configurations because God chose to so attach them. He could have chosen to do it differently. (Levine 1983, p. 359)
Levine won’t rely on God for metaphysics and finds himself pushing further and wanting to have an answer, but to no avail:
Now, so long as the two states of affairs seem arbitrarily stuck together in this way, imagination will pry them apart. Thus it is the non-intelligibility of the connection between the feeling of pain and its physical correlate that underlies the apparent contingency of that connection. (Levine 1983, p. 359)
In short, he finds himself with an explanatory gap between experience and physical processes. Levine believes that the materialist cannot close it and that it is inconceivable how some physical state, such as a brain state, could be the cause of experience. The same goes for functional states. A functional analysis of some experiential state, such as being in pain, does not help us understand why the experience must necessarily be the way it is. Levine believes that experiences could have physical causes. But he thinks we are utterly in the dark about them. Levine concludes that the mind-body problem remains.