The Enigma Of Reason: A New Theory Of Human Understanding

Hugo Mercier and Dan Sperber THE ENIGMA OF REASON A New Theory of Human Understanding Contents Introduction: A Double Enigma  I  SHAKING DOGMA  1 Reason on Trial  2 Psychologists’ Travails  II  UNDERSTANDING INFERENCE  3 From Unconscious Inferences to Intuitions  4 Modularity  5 Cognitive Opportunism  6 Metarepresentations  III  RETHINKING REASON  7 How We Use Reasons  8 Could Reason Be a Module?  9 Reasoning: Intuition and Reflection 10 Reason: What Is It For?  IV WHAT REASON CAN AND CANNOT DO 11 Why Is Reasoning Biased? 12 Quality Control: How We Evaluate Arguments 13 The Dark Side of Reason 14 A Reason for Everything 15 The Bright Side of Reason  V REASON IN THE WILD 16 Is Human Reason Universal? 17 Reasoning about Moral and Political Topics 18 Solitary Geniuses? Conclusion: In Praise of Reason after All Notes References Illustration Credits Acknowledgments Follow Penguin Introduction: A Double Enigma They drink and piss, eat and shit. They sleep and snore. They sweat and shiver. They lust. They mate. Their births and deaths are messy affairs. Animals, humans are animals! Ah, but humans, and humans alone, are endowed with reason. Reason sets them apart, high above other creatures—or so Western philosophers have claimed. The shame, the scandal of human animality, could at least be contained by invoking reason, the faculty that makes humans knowledgeable and wise. Reason rather than language—other animals seemed to have some form of language too. Reason rather than the soul—too mysterious. Endowed with reason, humans were still animals, but not beasts. Reason: A Flawed Superpower? With Darwin came the realization that whatever traits humans share as a species are not gifts of the gods but outcomes of biological evolution. Reason, being such a trait, must have evolved. And why not? Hasn’t natural selection produced many wondrous mechanisms? Take vision, for instance. Most animal species benefit from this amazing biological adaptation. Vision links dedicated external organs, the eyes, to specialized parts of the brain and manages to extract from patterns of retinal stimulation exquisitely precise information about the properties, location, and movement of distant objects. This is a hugely complex task—much more complex, by any account, than that of reason. Researchers in artificial intelligence have worked hard on modeling and implementing both vision and reasoning. Machine vision is still rudimentary; it comes nowhere near matching the performances of human vision. Many computer models of reasoning, on the other hand, have been claimed (somewhat optimistically) to perform even better than human reason. If vision could evolve, then why not reason? We are told that reason, even more than vision, is a general-purpose faculty. Reason elevates cognition to new heights. Without reason, animal cognition is bound by instinct; knowledge and action are drastically limited. Enhanced with reason, cognition can secure better knowledge in all domains and adjust action to novel and ambitious goals, or so the standard story goes. But wait: If reason is such a superpower, why should it, unlike vision, have evolved in only a single species? True, some outstanding adaptations are quite rare. Only a few species, such as bats, have well-developed echolocation systems. A bat emits ultrasounds that are echoed by surfaces in its environment. It uses these echoes to instantaneously identify and locate things such as obstacles or moving prey. Most other animals don’t do anything of the sort. Vision and echolocation have many features in common. One narrow range of radiation—light in the case of vision, ultrasounds in the case of echoloca