Locke's View of the Hard Problem of Consciousness and Its Implications for Neuroscience and Computer Science

Modern neuroscience has come to accept the challenge of understanding consciousness (Crick and Koch, 2003; Dehaene and Changeux, 2011). A major finding has been the discovery that there are conscious and unconscious systems in the brain (top and bottom of Figure 1, Lisman and Sternberg, 2013) and the development of methods for manipulating whether a sensory input will be consciously or unconsciously processed (Lamme, 2006). Interestingly, even stimuli that are not consciously processed can stimulate emotions and actions (Flykt et al., 2007). Despite this progress, there is the strong sentiment that the “hard” problem of consciousness has not been addressed. The hard problem deals with the question of how the feeling of consciousness arises. We feel conscious and the word seems easy to relate to our experience, but defining it is difficult. This impedes elucidation of the neural underpinnings of consciousness and makes it impossible to take a clear stand on whether a computer could be conscious. A recent meeting brought together experts in the hard problem, with two of the main protagonists being Daniel Dennett and David Chalmers. According to a report of this meeting (New Yorker, March 2017), Dennett believes that the brain is a collection of subsystems, with more advanced organisms having more subsystems. These subsystems interact to produce consciousness in a way that is greater than the sum of the parts. Moreover, consciousness is graded, with advanced organisms having much more of it than lower organisms. Chalmers’ view is quite different. He believes that consciousness can only be understood by including processes outside of the brain. According to the article, he has been “gravitating toward ‘pan-proto-psychism”’—the idea that consciousness might be “a fundamental property of the universe upon which the brain somehow draws.” I suggest that it is useful to consider a third idea about consciousness based on the ideas put forward by the philosopher John Locke (1603–1704) in his Essay Concerning Human Understanding, Book II, Chapter 1. Locke believed that there are two types of sensory input to the perceptual system, one from the sense organs and another from the “internal sense.” About this second input, Locke wrote: