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A Critique of Purely Weak Reason

August 2, 2010

At the Edge, moral psychologist Jonathan Haidt recommends a thought provoking paper on the function of reasoning in human interaction. In case you haven’t heard, it turns out Reason is a shameless lawyer kept on retainer by our desires. We’re hardwired to argue to attain higher in-group status and to form winning coalitions. Contrary to what intellectuals, Kant, Rawlsians, deliberative democrats, and other wordsmiths in the academic zoo will tell you, argument is seldom about truth seeking. It is about winning. Sez Haidt:

It’s called, “Why Do Humans Reason?  Arguments for an Argumentative Theory,” by Hugo Mercier and Dan Sperber. The article is a review of a puzzle that has bedeviled researchers in cognitive psychology and social cognition for a long time. The puzzle is, why are humans so amazingly bad at reasoning in some contexts, and so amazingly good in others?

So, for example, why can’t people solve the Wason Four-Card Task, lots of basic syllogisms?  Why do people sometimes do worse when you tell them to think about a problem or reason through it, than if you don’t give them any special instructions?

Why is the confirmation bias, in particular— this is the most damaging one of all—why is the confirmation bias so ineradicable?  That is, why do people automatically search for evidence to support whatever they start off believing, and why is it impossible to train them to undo that?  It’s almost impossible. Nobody’s found a way to teach critical thinking that gets people to automatically reflect on, well, what’s wrong with my position?

And finally, why is reasoning so biased and motivated whenever self-interest or self-presentation are at stake?  Wouldn’t it be adaptive to know the truth in social situations, before you then try to manipulate?

The answer, according to Mercier and Sperber, is that reasoning was not designed to pursue the truth. Reasoning was designed by evolution to help us win arguments. That’s why they call it The Argumentative Theory of Reasoning. So, as they put it, and it’s here on your handout, ‘The evidence reviewed here shows not only that reasoning falls quite short of reliably delivering rational beliefs and rational decisions. It may even be, in a variety of cases, detrimental to rationality. Reasoning can lead to poor outcomes, not because humans are bad at it, but because they systematically strive for arguments that justify their beliefs or their actions. This explains the confirmation bias, motivated reasoning, and reason-based choice, among other things.’

Here is one version of the paper. Our ignorance and the biases of deliberative reason bedevil our thinking about governance and national rule-sets. We may know our values but we don’t know how to ensure institutions, laws and norms will protect and nurture them. Our imaginations are also very weak. The credibility of any moral argument for one set of rules ought to be weighed against the weaknesses of the deliberative process of which it is part. Truth seeking does not come naturally so if we care about such things, we ought to pay greater attention to the incentives for finding them. In one on one moral argument, those incentives are rarely present.


  1. August 6, 2010 9:27 pm

    Thank you for talking about our work on your blog. You say however that our theory speaks against deliberative democracy. We claim on the contrary that deliberating in group can allow people to overcome the biases of reasoning, and thus that people reasoning together tend to produce good outcomes (at least when there’s a genuine debate — i.e. not everyone agrees in the first place).

    Here’s a submitted paper on that topic:

    • Mike Gibson permalink*
      August 6, 2010 11:28 pm

      Forgive my own confirmation bias! My eager hyperbole got in the way.

      And thanks for the reference to this paper. I look forward to plunging in.


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