On being importantly necessary for consciousness.

Engel et al. (1999) claim that ‘‘appropriate synchronization among cortical neurons may be one of the necessary conditions for the buildup of perceptual states and awareness of sensory stimuli.’’ The question I wish to examine in this brief comment is exactly what they mean by a ‘‘necessary condition’’ for consciousness. For example, gravity is surely necessary for human consciousness, for without gravity life itself would not be possible. On the other hand, when singling out the items of study for consciousness in the brain, gravity does not rank high on the list of possible suspects since there are other things also necessary that somehow seem closer to being sufficient for consciousness as well. I want to examine where on the continuum of items of interest for the study of consciousness neuronal synchronization is likely to rank: Does it resemble gravity or does it resemble substance(s) C, the sufficient factor(s)? Let me put my query another way. When we devise scientific theories to explain phenomena in the world, we single out some causal relations among the vast web of interactions as the important connections for understanding some event. Some causal influences are too trivial to matter much in a general theory; others are too far removed from the phenomenon in question to fall within the scope of a finite theory. Under normal circumstances, UV radiation would fall in the former category for any general theory of consciousness and breathable air would fall into the latter. Though my skull is constantly bombarded by ultraviolet radiation, its effects on my conscious experiences are quite minimal. Hence even a complete theory of consciousness can ignore UV effects, for successful theories highlight only the most important components and interactions in getting to the specified end state. Mutatis mutandis, oxygen supports mammalian life and being alive is a prerequisite for my being conscious. However, that I and creatures like me are alive and consuming oxygen are not going to be facts included in a theory explaining our conscious awareness. We can take life sustained in part by oxygen as a given background assumption and build a theory of consciousness on top of such facts. The question is what sort of phenomenon is neural synchrony? Is it too trivial or too far removed from conscious processing to matter in theory, even if it is necessary? Or is it more important than that?