It is possible to write a brilliant book with one, major and fundamental flaw? Yes, it's possible. That is what Hugo Mercier and Dan Sperber have done.
Those of you who have read Daniel Kahneman's "Thinking, Fast & Slow", will remember that he identified System 1 and System 2 in our thinking, with "1" being the more immediate intuitive response to thinking, and "2" the more rational side of our thinking.
Mercier and Sperber dismiss this approach, and prefer to present another way in which the brain works, primarily due to intuitive inferences of what we perceive or anticipate what other people will do or say. The evidence they present to make their case is excellent and very convincing. The use of abstract logic is indeed a rare thing. They explain how our mind has modules, little folders of knowledge, memory, expertise, that can be connected or not when confronted to a situation. And all that makes sense. They give the example of somebody walking into a doctor's waiting room, and the number of inferences made to appraise the situation in a flash moment is really spectacular.
They then explain how reasoning happens as a follow-up to inuitions, to justify our actions or to build arguments with other people. Again, what they say makes sense.
The big issue that I have with this approach is that it totally diminishes the role of the reasoning capabilities of the individual outside of social contexts. Truly, I reason the whole time. When I drive to the hospital, I will think about which route best to take depending on the time of day. That is not just an intuition. Surely, when they wrote their book, they reasoned alone. What about the car mechanic who has to solve the engine's troubles? He does not go about this inuitively. Just like the plumber who was called in to find the leak. Or the electrician to find a problem with the electricity.
I truly believe that humans can think logically in very concrete, pragmatic contexts. If I have five keys on my key ring, I will proceed with trial and error. If one key does not work, I will move to the next, remembering that the first key is not the right one. There is some logic in that. If the lamp next to my desk stops shining, I will check whether a new light bulb will solve the issue. If not, I will not keep changing light bulbs until I find one that works. No, I will check the wire, the socket, and so forth, until I have identified the problem. Mercier and Sperber are right that in more abstract and moral contexts, our sense of logic often fails, because of confirmation bias. But this confirmation bias is not active in pragmatic concrete contexts.
When there is immediate feedback, and in a pragmatic context, the reasoning will be flawless. When somebody wants to go shopping and the baker, the butcher, the grocer and the shoe shop are geographically located on one street, the person will automatically look for efficiency and go to these shops in the right sequence. He will not move erratically from the butcher to the baker then to the shoe shop and back to the grocer. No, his plan will be rational, pre-meditated, solitary and conscious.
Even worse, the authors attack people who might question their approach: "
Actually, the usual defences of the intellectualist approach to reason are themselves good examples of biased and lazy reasoning. It is an undisputed fact that individual reasoning is rarely if ever objective and impartial as it should be if the intellectualist approach were right".
Mercier and Sperber tell only half the story, namely reasoning in social contexts, and intuitive responses to moral choices, based on the theory of Jonathan Haidt. But Haidt was aware that his theory was only relevant for moral choices, not for all kinds of reasoning and intuitions. Somehow, Mercier and Sperber have missed this.
The whole success of humanity, is not only the social skill of being able to work together. Individuals have improved their hunting tactics by better reasoning (analysis of animal behavior, downwind approach, ...) as by their skills at perfecting weapons. The cleverest ones survived. The advantage of smart tools were as obvious in prehistory as they are now. Many of those are the results of clear logic, and inferences, without too much confirmation bias. There is no blow to self-esteem when one bow is not better than another bow. The hunter can identify why one type of wood is better for the bow, and why cat gut for strings are better than dog gut. There is no need for him to stick to cat gut because that happens to be his belief, just as I will not keep changing light bulbs without wondering whether the cause of the problem might not lie elsewhere.
In short, if Mercier and Sperber had written a book about social reasoning, or reasoning on a moral and abstract level, their book is fantastic. What they write is absolutely true, and much better than Kahnemann in my opinion. But their book ignores that reasoning can take place outside of social contexts, in the concrete and pragmatic environment of everyday life.
It's high time for both authors to get out of their ivory tower and do some handywork.
