Brain Specialization and Cognitive Closure

Brain Specialization and Cognitive Closure

Is the human brain intellectually limited? How limited might it be? Is it also limited emotionally and athletically and artistically? Suppose we ask the same question about the parts of the brain, the various functional structures gathered into a single brain—are they limited? For example, can the visual cortex perform all possible mental tasks—seeing everything, knowing everything, feeling everything? Obviously not: it is a specialized organ dedicated to certain specific tasks—seeing in general and seeing what this organism needs it to see. It is by no mean omnicompetent. Why on earth would it be? It is no more omnicompetent than the heart: this organ has the function of pumping blood around the animal’s body—not the function of pumping any old thing and certainly not performing non-pumping tasks. The same is obviously true of other brain parts (and body parts): they do a specific job and not any job you might come up with. They are like the parts of any machine—special purpose devices designed to do one sort of thing and not another. You put them all together and you get a functioning organism. No one would ever think the hypothalamus can do everything.

It is much the same with the two cerebral hemispheres, notoriously so. They have specialized functions, distinct identities or “personalities”. The left hemisphere, we are told, specializes in language, logic, motor control of the right side of the body, and the ability to focus; the right hemisphere is said to handle creativity, spatial skills, emotions, motor control of the left side of the body, and metaphor. The empirical facts are somewhat cloudy but the general picture is plausible enough: the brain in general tends to specialize according to area. There is lateralization of function as well as location of function. Accordingly, we don’t expect the left hemisphere to be able to do what the right hemisphere can do or vice versa (despite a degree of plasticity). One would expect cognitive (and other) closure with respect to the two hemispheres of the brain. Would anyone claim that the right hemisphere has the equipment to solve the mind-body problem, say? Then why does it seem reasonable to insist that the two limited hemispheres together could solve all problems? How can two limited things combine to produce an unlimited thing?

What is the function of the human brain? The same as the function of any animal’s brain—to aid survival. We need not think of this in a brutish primitive way—by all means include happiness and intellectual inquiry (worthwhile survival). The point is that each species has a specific lifestyle, with a distinctive type of body and reproductive procedure. We are bipedal and social; other animals are not.  There is no reason to believe that we, or any other known species, possess some sort of all-purpose brain power. We don’t possess an all-purpose body capable of any action and equipped for any environment. On the contrary, bodies are specialized according to their survival requirements—very specialized. The brain (mind) is really no different; it has its scope and limits. What would be the point of equipping it to do things it will never be called upon to do? Just think how impractical such a design might be. Organisms must economize not waste resources on quixotic ventures. The parts of the body and brain are thus specialized and the brain itself is an organ that obeys the same laws. You don’t need a heart that will pump up tires and you don’t need a brain that will pump out answers to any conceivable question. Such a thing is surplus to requirements, to put it mildly. Cognitive closure follows from the basic laws of biology.

Here is another way to conceptualize the point. The genes are very simple beings with only one thing on their little gene minds: survival. They build bodies that serve their limited purposes (no one thinks the genes could solve the mind-body problem!). The bodies they build contain organs that serve their purposes, including brains. Don’t expect these brains to be designed so as to solve any problem the universe throws at them. The genes would never make brains like that. Brains operate under tight constraints. The selfish gene is an intellectually limited gene. Not the dumb gene exactly, but certainly the austere and miserly gene. It’s amazing brains are as clever as they are.