Chapter 6 – The First Attack on Bayesianism and How It Can Be Answered

   

                                                     girls learning sign language 

                                     (credit: David Fulmer via Wikimedia Commons) 

The idea behind Bayesianism is straightforward enough to be grasped by nearly all adults in any land. But the idea of radical Bayesianism escapes us. The radical form of Bayesianism says all we do, mentally, fits inside the Bayesian model. But it is very human to dread such a view of ourselves and to slip into thinking that radical Bayesianism must be wrong. We want desperately to believe that at least a few of our core ideas are unshakeable. Too often, unfortunately, people think they have found one. But to a true Bayesian, the one truth that he believes is probably absolute is the one that says there are no absolute truths.

An idea is a mental tool that enables you to sort and respond to sensory experiences—single ones or whole categories of them. ("Aha. Balsamroot. Tasty. Yipe! Over here, poison ivy. Stay away.")  When you find an idea that enables quick, accurate sorting, you keep it. What can confuse and confound this whole picture is the way that, in the case of some of your most deeply held, deeply programmed, ideas, you didn’t personally find them. They came in a trial-and-error way to some of your ancestors, who found the ideas so useful that they then did their best to program these ideas into their children, and thus they were passed down the generations to your parents and then to you.

Almost every idea you acquire is added to your mental toolkit after careful Bayesian analysis and calculations, either by the process of your own noticing, considering, and testing it, or by your family and your tribe programming you with the idea because the tribe’s early leaders acquired that idea by the first process. 

Consciousness and even sanity are constantly evolving for all humans, all the time. We keep rewriting our concept sets, from complex ideas like justice and love to basic ideas like up and down and even to what I mean by I. (Individual minds can indeed be made to reprogram their notions of up and down.¹) Your barest you is a dynamic, self-referencing system that is constantly checking its perceptions of reality against its models/ideas about what reality should be and then updating itself.

A short side note is in order here. A few common species-wide ideas are not acquired by either of the above methods because these ideas are hardwired into us at birth. These are not programmed into humans by our tribes nor by our own life experiences so they don’t fit into either of the categories just described. But they do fit inside the empiricist view simply because in that view, with the models it has gained from the biological sciences, these built-in ideas are seen as genetically-acquired traits and thus as subjects for study by neurophysiologists or geneticists. In short, scientists can go looking for our really basic concepts directly in the human brain, and they do.

For example, some basic ideas of language are built into all normal humans. However, the genes that cause language centres to develop in the fetus’ brain are still being identified. In addition, the structures and functions of these brain areas are still poorly understood. 

In our present discussion, however, these issues can be passed by. They are biological rather than philosophical – hardware rather than software – so they are outside of our present scope. These genes and the brain structures that are built from the information coded in them may someday be manipulated, by genetic engineering, surgery, drugs, or behavior modification or even other technologies we cannot now imagine.

But whether such actions will be judged right or wrong and whether they will be allowed in our society will depend on our moral values. These, as we have already seen, are going to need something more at their core than what is offered by empiricism. Empiricism, as a moral guide, has shown itself to be unreliable in theory and practice. Science has so far failed at being its own moral guide. This line of thought returns us to our philosophical discussion of the foundations of moral codes—and so back to Bayesianism.