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.
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