The philosophy of science suggests that, on a fundamental level, a scientific theory is only a good theory to the extent that it fulfils a set of basic criteria of adequacy. The study of the predictive mind thus should benefit from an examination and evaluation of the extent to which theories of prediction adhere to these ground rules. There are six reasonable criteria further elucidated in this chapter that are useful to assess the merit of a theory. These criteria are far from perfect benchmarks but, considered as a whole, provide a useful guideline to evaluate theories of prediction. Six criteria are applied to theories of prediction in the remainder of the book. These are: parsimony and simplicity, theoretical precision and mechanistic specificity, testability and predictive power, falsifiability, test of time, and utility. The credibility of a scientific theory is also intrinsically connected to the credibility of the experimental evidence supporting it. This book uses three criteria that provide good benchmarks: the reliability, generalizability, and the validity of the experimental evidence that has been collected.