The attempt to delineate and characterize a particular period of history as an ‘age’, e.g. postmodernism. It assumes two things: first, that there is difference in kind (not just degree) between one moment in history and another; second, that there is something that gives a particular segment of time a certain kind of unity. In recent memory, the 1960s stands out as the most widely talked about example of period: according to some historians, it differs significantly from the 1950s because it is dominated by the ‘youth culture’ of the so-called baby boomer generation; it is unified by a shift in the structure of feeling away from believing in the idea of government towards a more dissident and rebellious position. Today, it is probably the notion of globalization that is the most talked about example of a periodizing hypothesis, though not everyone recognizes it as such (i.e. there are those who refuse it on the grounds that international trade has always been around). Further Reading: F. Jameson ‘Periodizing the 60s’ in The Ideologies of Theory (2008).