Monday, August 11, 2008

No one really uses reason by Chris Frith in New Scientist

No one really uses reason

THOUGH many may find it troubling, it is now clear that few of the active processes occurring in our brains ever impinge on our awareness. In other words, we do most of our "thinking" without ever being conscious of it.
The simple act of seeing something depends upon what the German physicist, doctor and philosopher Hermann von Helmholtz called "unconscious inferences". It is these that enable our brain to work out which object is causing the crude signals coming from our senses. The same principle applies to action. When we perform a simple action, picking up a glass, for example, we are not aware of the complex decisions our brain has to make about the best way to move our arm and shape our fingers.

It is a good thing that we are not aware of these low-level inferences. The truth is that we would never do anything if we had to think consciously about everything we see and every move we make. And it turns out that even quite important decisions involving many factors, such as choosing which car to buy, are better made if we don't consciously think about them. This is because the unconscious brain is very good at taking many things into account at the same time. We suspect that as soon as you start thinking about those things consciously, a brain system with very limited capacity is employed, which can concentrate on just a few items.

So where does conscious reasoning come into the picture? It is an attempt to justify the choice after it has been made. And it is, after all, the only way we have to try to explain to other people why we made a particular decision. But given our lack of access to the brain processes involved, our justification is often spurious: a post-hoc rationalisation, or even a confabulation - a "story" born of the confusion between imagination and memory.

Conscious reasoning is an attempt to justify a decision after it's made

Taking all of this into account, what then is reason? Just because our decisions are not conscious, it does not follow that reason is not involved. Given two options, the reasonable thing to do is to choose the better option. Brains are very good at doing this. After all, this is the basis of learning: to choose the nice things and avoid the nasty ones.

Economists and mathematicians, such as John Nash of A Beautiful Mind fame, have developed mathematical algorithms to ensure the best option is chosen - and brains have been shown to use similar mechanisms. The problem lies in deciding what we mean by "best". For Rational Economic Man, the best choice is the one that gets him the most gain. But do real people make such "best" choices?

In the experimental Ultimatum game, for example, suppose one player is given $10, and can give any proportion of this money to the second player. If the second player refuses their offer, then neither player gets any money. What should the second player do? The rational action is to accept any offer since some money is better than none. But in reality most people reject low offers.

This result is often understood to show that people are unreasonable, that their judgement is clouded by their emotional response to an unfair offer. However, from the point of view of the group, rather than the individual, the rejection of unfair offers is a good choice because it increases the likelihood of group cooperation and fairness. In this case, therefore, we can argue that our emotional responses are more reasonable than our conscious decisions.

In the 21st century,

we are discovering more and more about the brain and the role of emotion, and challenging old ideas about how we learn, make decisions, act and remember. This is already beginning to make us revise our notions of what constitutes reason - and that, in turn, is bound to have consequences for our attitudes to reason and to the endeavours of scientists.

Read about all the problems with reason in our special issue

Chris Frith is at the Wellcome Trust Centre for Neuroimaging, University College London. He wrote Making up the Mind (Blackwell, 2007)
From issue 2666 of New Scientist magazine, 23 July 2008, page 45

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