Data, Models, Theory and Reality: The Structure of Demographic Knowledge

Abstract

The development of demographic theory has been hampered by the widespread adherence — not always self-conscious — to the methodological doctrines of logical empiricism. According to this view, theory arises from empirical generalizations, and can be rejected if empirical exceptions or counter-examples are brought forward. An alternative view of theory sees it as an imaginative construction in response to data, a construction that is true by definition, but not a true description of the real world. As an abstraction it necessarily misrepresents the concrete world. The question is whether a theory is close enough to some part of the real world in certain respects to serve some well-defined purpose. Examples of this alternative view are found in the ‘semantic’ school of philosophy of science, but also in the work of some leading demographers and a few other social scientists. When seen from this alternate perspective, demography actually has more and better theory than is commonly thought.

This paper has been prepared for a workshop on ‘Agent-Based Computational Demography,’ at the Max Planck Institute for Demographic Research, Rostock, Germany, 21–23 February 2001, Francesco C. Billari and Alexia Furnkranz-Prskawetz, organisers. Some portions of the paper were presented earlier at a Workshop on Synthetic Biographies, organised jointly by the University of Groningen and the University of Pisa (San Miniato, Italy, June 1999), and at a Workshop on Longitudinal Research, organised by the Population Studies Centre, University of Western Ontario (London, Canada, October 1999 — see Rajulton, 2001). Ongoing research on modelling and demographic theory has been supported by the Social Sciences and Humanities Research Council of Canada. The author is Professor Emeritus, Population Studies Centre, University of Western Ontario, London, Canada.