Now, at this point in the discussion, opponents of Bayesianism begin to marshal their forces. Critics of Bayesianism give several varied reasons for continuing to disagree with the Bayesian model, but I want to deal with just two of the most telling—one is practical and evidence-based, and the other, which I’ll discuss in the next chapter, is purely theoretical.

        

                                        Elizabeth Eckerd (center) being taunted in Arkansas, 1957

In the first place, say the critics, Bayesianism simply can’t be an accurate model of how humans think because humans violate Bayesian principles of rationality every day. Every day, we commit acts that are at odds with what both reasoning and experience have shown us is rational. Some societies still execute criminals. Men continue to bully and exploit, even beat, women. Some adults still spank children. We fear people who look different from us on no other grounds than that they look different from us. We shun them even when we have evidence showing there are many trustworthy individuals in that other group and many untrustworthy ones in the group of people who look like us. We do these things even when research indicates that such behaviour and beliefs are counterproductive.

Over and over, we act in ways that are illogical by Bayesianism’s own standards. We stake the best of our human and material resources on ways of behaving that both reasoning and evidence say are not likely to work. Can Bayesianism account for these glaring bits of evidence that are inconsistent with its model of human thinking?

The answer to this critique is disturbing. The problem is not that the Bayesian model doesn’t work as an explanation of human behaviour and thinking. The problem is rather that the Bayesian model of human thinking and the behaviours driven by that thinking works too well. The irrational behaviours individual humans engage in are not proof of Bayesianism’s inadequacy, but rather proof of how it applies to the thinking, learning, and behaviour of individuals and also to the thinking, learning, and behaviour of whole communities and even whole nations.

Societies evolve and change because they each contain some people who are naturally curious. These curious people constantly imagine and test new ideas and new ways of doing things like obtaining food, raising kids, fighting off invaders, healing the sick—any of the things the society must do in order to carry on. Often, other subgroups in society view any new idea or way of doing things as threatening to their most deeply held beliefs. If the adherents of the new idea keep demonstrating that their idea works and that the more intransigent group’s old ways are obsolete, then the larger society will usually marginalize the less effectual members and their system of ideas. In this way, a society mirrors what an individual does when he finds a better way of growing onions or teaching kids or easing Papa’s arthritic pain. In this way, we adapt—as individuals, but more profoundly, as societies—to new lands and markets and to new technologies such as vaccinations, cars, televisions, computers, and so on. Farmers, cooks, and teachers who cling to obsolete methods are simply passed by, eventually even by their own grandchildren.

But then there are the more disturbing cases, the ones that caused me to write nearly always above. Sometimes large minorities or even majorities of citizens hang on to obsolete concepts and ways.

The Bayesian model of human thinking works well, most of the time, to explain how individuals form and evolve their basic idea systems. Most of the time, it also can explain how a whole community, tribe, or nation can grow and change its sets of beliefs, thinking styles, customs, and practices. But can it account for the times when majorities in a society do not embrace a new way in spite of the Bayesian calculations showing the idea is sound? In short, can the Bayesian model explain the dark side of tribalism?

                                          Nazi party rally, 1938. Tribalism at its worst

As we saw in our last chapter, for the most part, individuals become willing to drop a set of ideas that seems to be losing its effectiveness when they also encounter a new set of ideas that looks more promising. They embrace the new ideas that perform well, that guide the individual well through the hazards of real life. Similarly, at the tribal level, whole societies usually drop paradigms, and the ways of thinking and living based on those paradigms, when the citizens repeatedly see that the old ideas are no longer working and that a set of new ideas is getting better results. Sometimes, on the level of radical social change, this mechanism can cause societies to marginalize or ostracize subcultures that refuse to let go of the old ways. Cars and car people marginalized the horse culture within a generation. Assembly line factories brought the unit cost of goods down until millions who had once accepted that they would never have a car or a t.v. bought one on payments and owned it in two years. The old small scale shop in which a team of sixteen men made whole cars, one at a time, was obsolete.

The point is that when a new subculture with new beliefs and ways keeps getting good results, and the old subculture keeps proving ineffectual by comparison, the majority usually do make the switch to the new way—of chipping flint, growing corn, spearing fish, making arrows, weaving cloth, building ships, forging gun barrels, dispersing capital to the enterprises with the best growth potential, or connecting a computer to the Internet.

It is also important to state here that, for most new paradigms and practices, the tests applied to them over the decades only confirm that the old way is still better. Most new ideas are tested and found to be less effective than the established ones. Only rarely does a superior one come along.

But the more crucial insight is the one that comes next. Sometimes, if a new paradigm challenges a tribe’s most sensitive central beliefs, the Bayesian calculations about what individuals and their society will do next break down, and most tribes continue to adhere to the old beliefs. The larger question here is whether the Bayesian model of human thinking, when it is taken up to the level of human social evolution, can account for these apparently un-Bayesian behaviors.

Many of our most deeply held beliefs concern areas of our lives that govern our interactions with other humans—family members, friends, neighbors, colleagues, and fellow citizens. These are areas we have long seen, and mostly still see, as being guided not by reason but by sensitive moral beliefs—beliefs derived in different ways from those about the physical world. In anthropological terms, these are the beliefs that enable the members of the tribe to live together, interact, work in teams, and get along.

The continued exploitation of women and execution of murderers mentioned above are consequences of the fact that in spite of our worries about the failures of our moral code in the last hundred years, much of that code lingers on. In many aspects of our lives, we are still drifting with the ways that were familiar, even though our confidence in those ways is eroding around us. We don’t know what else to do. In the meantime, these traditional ways are so deeply ingrained and familiar as to seem natural for many people, even automatic, in spite of evidence to the contrary.

When we study the deepest and most profound of these “traditional” behaviors and beliefs, we are dealing with those beliefs that are most powerfully programmed into every child by all of the tribe’s adult members. These beliefs aren’t subject to the Bayesian models and laws that usually govern the learning processes of the individual human. In fact, they are almost always viewed by the individual as the most important parts of his culture and himself. They are guarded in the psyche by emotional associations that elicit anger and fear when disturbed. They are the beliefs and morés your parents, teachers, storytellers, and leaders enjoined you to hang on to at all cost. In fact, for most people in most societies, these beliefs and the morés that emerge from them are seen as being simply normal. Varying from them is abnormal.

        

                            artist's conception of Moses receiving 10 commandments from God

For centuries, in the West, our moral meta-belief—that is to say, our belief about our moral beliefs—was that they had been set down by God and, therefore, were universal and eternal. When we took that view, we were in effect placing our moral beliefs in a separate category from the rest, a category meant to guarantee their inviolability. Non-Western societies do the same.