The explanation gap, according to Levine, is that no theory of the physical realization of consciousness in the brain that uses only natural science terms can eliminate the feeling that something remains unexplained. Suppose it is scientifically proven that pain is a C-fiber excitation and its attendant processes in all relevant areas of the brain. Nevertheless, there is more to the concept of pain that people use than the idea of the causal role it plays. There is also its qualitative character, what it is like to feel pain. After discovering C-fiber arousal, what remains unexplained is why pain feels the way it does. Accordingly, psychophysical identity statements differ from other theoretical statements because people’s subjective experiences accompany them. Consciousness is something that cannot be abstracted and observed from the outside; besides, it is largely unknowable, which cannot be said about water and its properties.
Joseph Levine coined the term explanatory gap in 1983 to refer to the same problem as the hard problem of consciousness. The latter arises because phenomenal consciousness does not apply to standard functional explanations. For example, those methods that are used quite successfully in psychology to study various types of mental activity become inapplicable. According to the scholar’s view, this is why materialistic theories of consciousness cannot explain the existence of qualia. Problems in understanding the nature of psychophysical identity statements cannot be solved by specifying laws and mechanisms and calculating probabilities. A situation arises where no satisfactory scientific explanation of the phenomenon under study exists. Even if one thoroughly studies brain processes and the laws of physics and creates all the necessary physical conditions for the emergence of consciousness, there is no certainty that it will appear. This is why these kinds of statements leave a significant gap in the explanation.