<p>This paper presents the rules of science in general as the rules of <i>social</i> science and describes what makes a good theory in both science generally and social science specifically. We argue that good theory in science and social science can both explain and predict. Scientific theory at any level of analysis consists of deductively connected models of processes, and these processes and the entities they involve almost always are ideal types. Good scientific theory is always consistent with good theories at lower levels of analysis. We also explain why evolutionary theory is a good theory for social science and provides the best possible model (or ideal type) of the individual. We note its consistency with science at a lower level of analysis (biology), its mathematical basis, and its ability to predict population trends (including those not predicted by other social science theory). Last, we argue that the use of evolutionary theory in social science should be supplemented with further work on ontogeny (developmental processes) and proximate mechanisms.</p>