Steven Pinker -- How the Mind Works - Hampshire High Italian ...

Good Ideas 311diverge so unevenly that some of their scions are almost unrecognizable.Those branchlets have to be hacked off to keep the category as we knowit, and the main branch is disfigured by jagged stumps. It turns into afuzzy category whose boundaries are defined by similarity, without acrisp scientific definition.Fish, for example, do not occupy one branch in the tree of life. One oftheir kind, a lungfish, begot the amphibians, whose descendantsembrace the reptiles, whose descendants embrace the birds and themammals. There is no definition that picks out all and only the fish, nobranch of the tree of life that includes salmon and lungfish but excludeslizards and cows. Taxonomists fiercely debate what to do with categorieslike fish that are obvious to any child but have no scientific definitionbecause they are neither species nor clades. Some insist that there is nosuch thing as a fish; it is merely a layperson's stereotype. Others try torehabilitate everyday categories like fish using computer algorithms thatsort creatures into clusters sharing properties. Still others wonder whatthe fuss is about; they see categories like families and orders as mattersof convenience and taste—which similarities are important for the discussionat hand.Classification is particularly fuzzy at the stump where a branch washacked off, that is, the extinct species that became the inauspiciousancestor of a new group. The fossil Archaeopteryx, thought to be theancestor of the birds, has been described by one paleontologist as "a pisspoorreptile, and not very much of a bird." The anachronistic shoehorningof extinct animals into the modern categories they spawned was abad habit of early paleontologists, dramatically recounted in Gould'sWonderful Life.So the world sometimes presents us with fuzzy categories, and registeringtheir similarities is the best we can do. Now we may turn thequestion around. Does the world ever present us with crisp categories?In his book Women, Fire, and Dangerous Things, named after a fuzzy grammaticalcategory in an Australian language, the linguist George Lakoffargues that pristine categories are fictions. They are artifacts of the badhabit of seeking definitions, a habit that we inherited from Aristotle andnow must shake off. He defies his readers to find a sharp-edged category in