Sunday, 6 November 2011

The Believing Brain

William James is supposed to have said, "Thinking is what a great many people think they are doing when they are merely rearranging their prejudices."  Courtesy of a tip from Roo and the friendly folk at the Brisbane City Council library service, I've finally got my hands on Michael Shermer's The Believing Brain, which explains this aphorism in a lot more detail.

I previously encountered Shermer through his Why People Believe Weird Things, a fun journey through a set of beliefs on the edge of the intellectual world like Holocaust denial, alien abduction, Ayn Rand's Objectivism and the psi quotient.  Shermer revealed himself as an intensely curious, sympathetic but highly skeptical observer, constantly on the hunt for evidence. 

The Believing Brain covers some of the same territory but it's a much more technical book dealing with the question from the point of view of Shermer's own specialist field, neuro-psychology.  What it is about our brains, Shermer wants us to know, that makes us so prone to belief, of whatever kind?

There's a lot of detail about the operation of neurons and brain chemicals, the functions of different parts of the brain, and the way our brains respond to certain stimuli.  What it comes down to, though, is three things - patternicity, agenticity and bias. 

Patternicity: Our brains have evolved to seek and recognise patterns in their surrounding environment.  A primitive hominid, wandering in the jungles of Africa, hears the rustling of leaves.  It could be a lion about to turn him or her into dinner.  It could also just be the wind in the leaves.  The hominid has to make an instant decision.  The one who assumes it is a lion and runs away is likely to survive, irrespective of whether there actually is a lion.  The one that doesn't is likely to be eaten.  The one that runs away is our ancestor.  Hence, an inability to see patterns where they actually exist is fatal, but a tendency to percieve non-existent patterns has no evolutionary cost, so it is likely to persist.

Agenticity: Part of the reason our ancestors were so successful in doing this is that they were able to perceive the intentions of other creatures - both people and animals.  "That lion plans to eat me".  A peculiar characteristic of our species is that we attribute agency to all sorts of things, including things like rocks, trees, the sky and so on which actually have no intentions. 

Bias: These tendencies are far from superficial - they lie at the basis of our brain function, encoded in the way our brains work, in the electrical impulses and interplay of brain chemicals that accompany thought.  The result, says Shermer, is that our beliefs are seldom formed through a rational examination of the evidence.  Belief comes first, evidence follows, and we automatically look for evidence which supports our pre-existing beliefs, noticing the supporting facts and screening out the contradictory ones.

From this basis, he moves on to discuss various beliefs, especially focusing on alien visitations, belief in God, political ideology and conspiracy theories.  I found his discussion of visitations (whether by aliens, ghosts, spirits or angels) fascinating.  Our brain, he says, creates an image of our body, repeated in each brain hemisphere.  Perhaps, he says, if these mirror images get out of sync, as they are prone to under pressure - for instance, for solo climbers in the Himalayas, or in the early morning hours of a stressful period in someone's life - the brain will have two rival body images.  Because it knows there should only be one, it seeks a pattern to explain the other and lights on something from memory or culture - an alien, an angel, the ghost of a parent.  He describes how such hallucinations can be reproduced in the laboratory by electrically stimulating certain parts of the brain.  The patterns we find match what we expect to find, but don't correspond to any objective reality.

What is the answer to this sea of irrationality?  Of course you guessed it, it's Science.  The scientific method provides a methodology of controlled experimentation to collect objective evidence, statistical techniques to analyse this evidence, and a system of peer review in which rival scientists will gleefully pull your conclusions to bits if they don't match the evidence.  He doesn't claim perfection for this system, or that scientists are immune from the processes that drive belief, but what he does assert is that it's the best way to arrive at reliable knowledge and to test these beliefs.

One of the things I enjoy about Shermer is the fact that he doesn't overclaim on his evidence.  There is a lot that we know about the functioning of our brains, but also a lot we don't, and words like "might" and "perhaps" appear a lot in this book.  Shermer is happy to speculate but it is generally clear when he is.  He is also clear what his analysis does not prove.

Explaining why someone believes in democracy does not explain away democracy; explaining why someone holds liberal or conservative values within a democracy does not explain away those values.

Indeed.  One thing Shermer skates over, although I am sure he is aware of it, is the distinction between correlation and causality.  It is possible to track what is happening electrically and chemically in our brains as we perform certain types of thought or respond to certain stimuli.  Does this mean the chemical and electronic activity causes the thoughts, or do the thoughts cause the activity?  If you produce hallucinations by electrically stimulating parts of the brain, these hallucinations are not caused by the brain's electrical activity, but by the experimenter's stimulation of it.  In the absence of such artificial stimulation, what else causes these things?  Are the causes always the same?  Shermer is forced back on "might" and "perhaps". 

This is where his own biases are clearly on show, and he makes no attempt to hide them.  He is a materialist, believing that everything has a "natural" cause.  Humans are purely physical - when our body dies, there is nothing else of us to continue on.  There is no god.  This is not the result of his examination of the evidence - he himself is clear that there is no evidence - it is his own philosophical position.  He believes that the burden of proof lies with those who claim otherwise, since something which cannot be proven to exist probably doesn't.  Yet this assumption means that he sees the evidence in a particular way.  All his "perhapses" are naturalistic explanations.  He never says "perhaps some of them really did see angels". 

Shermer devotes the first three chapters of his book to outlining three different world views.  The first is that of a self-taught former bricklayer who once heard a disembodied voice speaking to him, and has built his life around what it said.  The third is devoted to explaining his own world view - converted to fundamentalist Christianity in his teens before drifting towards atheism as the scientific evidence against his version of belief piled up.  Yet he balances his journey from fundamentalism to skepticism with the journey in the opposite direction of distinguished geneticist Dr Francis Collins, who converted to evangelical Christianity in his 20s and has retained this belief alongside considerable scientific eminence.  Shermer is not just being polite when he says that his reasoning does not disprove God's existence - there are enough believers with high level scientific training to show this is an established fact.

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