To over-generalize, there are two types of nonfiction books worth reading: those written by an eminent specialist summarizing the current state of his or her field, often focusing on the singular idea that defines the author's career; and those written by a journalist without special knowledge about the field, tracking a particular idea, crossing the boundaries of disciplines when required by the pursuit. Malcolm Gladwell's Blink is a bravura example of the latter sort of book: he ranges through art museums, emergency rooms, police cars, and psychology laboratories following a skill he terms 'rapid cognition.'
Rapid cognition is the sort of snap decision-making performed without thinking about how one is thinking, faster and often more correctly than the logical part of the brain can manage. Gladwell sets himself three tasks: to convince the reader that these snap judgments can be as good or better than reasoned conclusions, to discover where and when rapid cognition proves a poor strategy, and to examine how the rapid cognition's results can be improved. Achieving three tasks, Gladwell marshals anecdotes, statistics, and a little bit of theory to persuasively argue his case.