That is, each method will be evaluated on its ability to provide reliable and valid measurements of concepts according to the rules set forth in the philosophy of science. Of course, there is no one philosophy of science nor set of rules. But this complexity simply makes our learning experience all the more interesting. Science differs from the Logico-Deductive epistemology in that it requires also the testing or development of theory. Theory is a set of empirically testable, abstract statements about reality.
Science requires theory for three reasons.
First, theory permits a much more productive and efficient way of summarizing observations about reality than empirical generalizations , which summarize in concrete terms only empirical events. Fishbein and Ajzen's theory of rational expectations, for example, is a set of abstract statements that can and have been applied successfully to understanding and predicting a very wide range of behaviors. Limitations to the theory of rational expectations discovered in a study of one behavior, for example, might help to understand or predict another behavior. Good theory provides good explanations of why events occur, which enables people to make better choices about how to shape their environment. To say that science necessarily entails the use of theory is not to say that science must be deductive.