Source: Brett Sayles/Pexels

Consciousness is like a rainbow in that it arises from a particular set of circumstances. For there to be a rainbow, several conditions must be met. Rainbows don’t just spring up everywhere. They are not an inherent property of matter or of the universe. Rainbows arise from these circumstances and not from just anything.

The same can be said for lasers, audio recording, digestion, memory retrieval, and air conditioning. These things do not spring from thin air: They stem from physical structures that are configured to instantiate these particular functions, just as the human eye evolved for seeing and the ear evolved for hearing, and eyes can’t hear, and ears can’t see. Similarly, in the study of vision, it is well-known that some neural circuits are devoted to certain kinds of perceptual analysis, such as “edge enhancement” (to detect the boundaries of objects) and motion detection (e.g., the Reichardt detector). Because of their arrangement, the neurons doing motion detection cannot do memory retrieval or music appreciation, and vice versa.

Consciousness is another achievement of the brain, instantiated by the activities of nerve cells and how they are configured to instantiate this particular cognitive phenomenon. And this is the mainstream view: Not all circuits in the brain are associated with consciousness, just as not all parts of a car are associated with, say, the navigational system. The circuitry of the car’s navigational system is different from that of the transmission.

Consciousness is (somehow) instantiated by neural activities configured to instantiate consciousness. There is overwhelming evidence that this is the case, as is known by any anesthesiologist. Not all brain circuits are involved with instantiating consciousness. For example, there is overwhelming evidence that the cerebellum, which has more neurons than the cortex, is not responsible for instantiating consciousness. All the neurons in the cerebellum do not “do” consciousness. They are wired in extremely sophisticated ways to do other things. There is something about the arrangement of the neural circuits associated with consciousness that permits them to instantiate this phenomenon, just as there is something about the components of a toaster that make a toaster capable of toasting toast. A blender cannot toast, and a toaster cannot blend.

Analogously, the neurons involved in the pupillary reflex are not involved in memory retrieval and are not configured to carry out such a process, just as a toaster is not configured to record music, and a television is not configured to make toast. To say that toast “emerges” from the complexity of a toaster does little to explain how a toaster works.

Someone who subscribes to panpsychism would disagree with this view because, according to the panpsychist standpoint, consciousness is a property of all matter. (This is not the traditional, mainstream view of the brain.) From this standpoint, consciousness is not an achievement of the brain; it is a freebie provided (somehow) by the universe and its matter.

A friend of mine who is a panpsychist explained to me that a doorknob is conscious. I asked if it is conscious in the way that you and I are conscious. He said, “No, it is not.” I then asked why not, and he replied that it has something to do with our brains. The doorknob has only a kind of “proto-consciousness,” and we, because of our brain circuitry, have “real consciousness.”

So the question now becomes, “What is special about our brain that allows it to produce real consciousness instead of just proto-consciousness (whatever that might be)?” My friend confessed that we have simply replaced one mystery with another. Moreover, my friend and I agreed that our new question (what is special about the brain that makes it "real" conscious) is worth solving and that to solve it, one must investigate not the doorknob but a subset of circuits in the brain.