At one level, sociology is easy to define. It is the study of social institutions – the family, religion, sport, community, and so on. We can study institutions at the micro-level by looking at interactions between family members, for example, or we can examine macro-relations such as the family and kinship system of a society as a whole. Below this level of minimal agreement, there is considerable dispute as to what sociology really is, and during the twentieth century and into this century many critics of sociology have periodically pronounced it to be in crisis or to be moribund. It is said to be prone to jargon, or it is claimed by its critics to be merely common sense. A natural scientist at my former Cambridge college, on hearing that...