This book follows on from, and at various points exploits, my earlier work On Sociology (2nd edn 2007). It has, however, a significantly different character. On Sociology was a collection of rather diverse essays that were brought together under the headings of ‘Critique and Program’ (volume 1) and ‘Illustration and Retrospect’ (volume 2). These essays were mainly written around the turn of the century – a time of intense debate over how sociology as an academic and intellectual enterprise should be viewed and of great uncertainty over the future course of its development. During more recent years I have become aware of a significantly changing situation. Some at least of the kinds of sociology that I earlier criticised – for example, ‘grand’ historical sociology and ‘post-modernist’ ethnography – would appear to have fallen into decline; and, of greater consequence, the version of sociology that I argued for programmatically and sought to illustrate has, at least in certain respects, flourished to a degree that I find surprising – although, of course, pleasantly so. I would naturally like to see evidence here of the influence of On Sociology; but, as a good Popperian, I have to accord crucial importance to the ‘logic of the situation’. Research designed to address well-defined sociological problems and based on the quantitative analysis of extensive and high-quality data-sets – even if not backed by theoretical advance to the extent I might wish – has been increasingly recognised as having premium payoffs, in both its ‘pure’ and ‘applied’ aspects, and has in turn become increasingly attractive to working sociologists and to funding agencies alike.

Consequently, there now appears to be less need than previously for critical or programmatic interventions, and I would, in turn, wish to emphasise the following point regarding the present work. In seeking to make out the case for an understanding of sociology as a population science, my main concern is not to propose to sociologists how they should conceive of and practise their subject. It is rather to suggest a way in which a fuller and more explicit rationale than has hitherto been available might be provided for what a large and steadily growing number of sociologists in fact already do – although, perhaps, without a great deal of reflection on the matter. If asked what purpose the elaboration of such a rationale might serve, my response would be twofold.