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

     

                                  ophidiophobia is now thought to be genetically  inherited  

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 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. 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 to you.

Every idea you acquire is installed as part of your mental equipment, after careful Bayesian calculations, either by the process of your own noticing, speculating, 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 your sense perceptions against your ideas about what reality should be and then updating and rewriting itself.

                                                   dealing with acrophobia, the fear of heights

A short side note is in order here. A few commonly used, species-wide ideas, or proto-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 tribe nor by our own life experiences, so they don’t fit into either of the categories just described. But they do fit inside the modern empiricist view of what knowledge is simply because in that view, with the models it has gained from the biological sciences, especially genetics, these built-in ideas are seen as genetically acquired anatomical traits and thus as subjects for study by geneticists or neurophysiologists. In short, scientists can go looking for them directly in the human brain, and they do.

For example, some basic of our basic fears are now thought to be built into our brains from birth. Having these fears "factory-installed" in a human being's brain had survival advantages. Thus, over generations, they became part of our basic equipment. 

On the more positive side, some ideas of language are also built into all normal humans. But the genes that cause the fetus to build language centres into its developing brain are still being identified. In addition, the structures and functions of these brain areas, once they’re built, are poorly understood. In our present discussion, however, these issues can be passed by. They are biological rather than philosophical in nature, and thus outside our present scope. These genes and the brain structures that are built from the gene-coded information might someday be manipulated, either by behavior modification, genetic engineering, surgery, drugs, or other technologies we cannot now imagine.

                               

            babies' learning to talk happens too rapidly to be explained by nurture alone

Whether such actions will be judged right or wrong and whether they will be permitted in the normal institutions of 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 its own moral guide, has proved neither sound in theory nor effective in practice. The evidence of human history strongly suggests that science, at least so far, has failed at being its own moral guide. This line of thought returns us to our philosophical discussion of moralities and their sources—and so back to Bayesianism.

This Bayesian model of how we think is so radical that at first it eludes us. To each individual, the idea that she is continually adjusting her entire mindset, and that no parts of it, not even her deepest ideas of who she is or what reality is, can ever be fully trusted is disturbing to say the least. Doubting our most basic ideas is flirting on the edge of mental illness. Even considering the possibility is upsetting. But this radical Bayesian view is certainly the one I arrive at when I look back honestly over the changes I have undergone in my own life. The Bayesian model of how a “self” is formed, and how it evolves as the organism ages, fits the set of memories that I call “myself” exactly.

Thomas Kuhn was the most famous of the philosophers who have examined the processes by which people adopt a new theory, model, or way of knowing. His works focused only on how scientists adopt a new scientific model, but his conclusions can be applied to all human thinking. His most famous book proposes that all our ways of knowing, even our most cherished ones, are tentative and arbitrary.² Under his model of how human knowledge grows, humans advance from an obsolete idea or model to a newer, more comprehensive one by paradigm shifts— that is by leaps and starts rather than in a steady march of gradually growing enlightenment. We “get”, and then start to think under, a new model for organizing our thoughts by a kind of conversion experience, not by a gradual process of persuasion and growing understanding.

Caution and vigilance seem to be the only rational attitudes to take under such a view of the universe and the human place in it. To many people, the idea that all of the mind’s systems—and its systems for organizing systems and perhaps even its overriding operating system, its sanity—are tentative and are subject to constant revision seems even more than disturbing; it seems absurd. But then again, cognitive dissonance theory would lead us to predict that humans would quickly dismiss such a scary picture of themselves. We don’t like to see ourselves as lacking in any unshakeable principles or beliefs. However, evidence and experience suggest we are indeed almost completely lacking in fixed concepts or beliefs, and we do nearly always evolve personally in those scary ways. (Why I say nearly always and almost completely will become clear shortly.)