Philosophical analysis of axiomatic methods goes back at least to Aristotle. In the large literature of many centuries a great variety of ssues have been raised by those holding viewpoints that range from that of Proclus to that of Hilbert. Here I try to consider in detail only a highly selected set of ideas, but they are ones I judge important. The first section gives a brief overview of the formalization of theories within frrst-order logic. The second section develops the axiomatic characterization of scientific theories as set-theoretical predicates. This approach to the foundations of theories is then related to the older history of the axiomatic method in the following section. 1. Theories with Standard Formalization A theory with st...