Introduction

The horizontal divisions within society, such as cohort, age group and generation, have had considerably less attention paid to them than the vertical divisions of class, gender and ethnicity. This may reflect the starker social polarisation that emerged during the course of industrialisation, a polarisation that preoccupied the founders of the emergent social sciences. Horizontal divisions within society may have been recognised but they were not seen as so significant, or as key sites of social conflict. While there is still continued debate regarding the nature and significance of many of the vertical divisions in society, the importance of horizontal divisions has become more prominent. Indeed, some writers now argue that in contemporary society, generation is replacing class as the key site of contemporary social conflict (Turner, 1989; Becker, 1991). All of this makes it important to clarify the different but related horizontal divisions reflected in terms such as ‘age group’, ‘stage of life’, ‘cohort’, ‘period’ and ‘generation’.

Erdman Palmore (1978) pointed out that in most social science research, the need to separate age effects from period and cohort effects is inescapable. Not only are there ageing processes and issues of human development to deal with, but differences between generations and trends over time potentially confound any interpretation based on chronological age. While Palmore argued that it is always important to measure all three types of difference, doing so has always been a problem. Chronological age at least has the virtue of being an ordinal value, even though what a particular age may mean is historically contingent. Period, as has been seen in Chapter Two, is more contentious, as is the idea of generation, since both rely on interpretation. Even the idea of cohort, which seems straightforward, depends for much of its meaning on its conflation with generational effects.

These issues are highlighted in any consideration of the use of the term ‘generation’. Two approaches dominate the conceptualisation of this problem. The first is associated with the demographer Norman Ryder, who argued that ‘cohort’ was a more ‘neutral’ concept for understanding the interplay between history and biography than terms such as generation. He defined cohort as ‘that aggregate of individuals who experienced the same event within the same time interval … [where typically] the defining event has been birth’ (Ryder, 1997, p 68).