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

Thinking Machines 127Taylor are grandmothers (indeed, a Jewish grandmother, in Taylor's case).When it comes to bachelors, many people—such as immigration authorities,justices of the peace, and health care bureaucrats—are notoriouslyMwfuzzy about who belongs in the category; as we all know, a lot canhinge on a piece of paper. Examples of unfuzzy thinking are everywhere.A judge may free an obviously guilty suspect on a technicality. Bartendersdeny beer to a responsible adult the day before his twenty-firstbirthday. We joke that you can't be a little bit pregnant or a little bit married,and after a Canadian survey reported that married women have sex1.57 times a week, the cartoonist Terry Mosher drew a woman sitting upin bed beside her dozing husband and muttering, "Well, that was .57."In fact, fuzzy and crisp versions of the same category can live side by sidein a single head. The psychologists Sharon Armstrong, Henry Gleitman,and Lila Gleitman mischievously gave the standard tests for fuzzy categoriesto university students but asked them about knife-edged categorieslike "odd number" and "female." The subjects happily agreed to daft statementssuch as that 13 is a better example of an odd number than 23 is,and that a mother is a better example of a female than a comedienne is.Moments later the subjects also claimed that a number either is odd or iseven, and that a person either is female or is male, with no gray areas.People think in two modes. They can form fuzzy stereotypes by uninsightfullysoaking up correlations among properties, taking advantage ofthe fact that things in the world tend to fall into clusters (things that barkalso bite and lift their legs at hydrants). But people can also create systemsof rules—intuitive theories—that define categories in terms of therules that apply to them, and that treat all the members of the categoryequally. All cultures have systems of formal kinship rules, often so precisethat one can prove theorems in them. Our own kinship system givesus a crisp version of "grandmother": the mother of a parent, muffins bedamned. Law, arithmetic, folk science, and social conventions (withtheir rites of passage sharply delineating adults from children and husbandsfrom bachelors) are other rule systems in which people all over theplanet reckon. The grammar of a language is yet another.Rule systems allow us to rise above mere similarity and reach conclusionsbased on explanations. Hinton, Rumelhart, and McClelland wrote:"People are good at generalizing newly acquired knowledge. If, for example,you learn that chimpanzees like onions you will probably raise yourestimate of the probability that gorillas like onions. In a network thatuses distributed representations, this kind of generalization is auto-