An aspect of rational behaviour is rational belief. Criteria for belief in generalisations as distinct from propositions about specific events are what characterise the social sciences. Central to this is statistical analysis, though of course it is not the whole story. The use and limitations of statistical methods in the analysis of war are considered. In this part, some issues of conflict on the international scene are discussed which both are substantively important and also illustrate the ways in which we try to establish propositions about social behaviour and consider their truth or otherwise.