The above title leads quite naturally to two sets of questions: (1) What is philosophy of theology? Is it the same as philosophy of religion? Is it the same as philosophical theology? Philosophy of theology is not the same as either philosophy of religion or philosophical theology. Rather, philosophy of theology is a branch of philosophy of science in general, just as philosophy of physics, philosophy of biology or philosophy of psychology. (2) If philosophy of theology is a branch of philosophy of science in general, then how can Karl Popper's work in the philosophy of science prove fruitful for the development of a philosophy of theology? Does not Popper maintain that scientific assertions must be falsifiable by experience? How can one maintain, within a Popperian perspective, that philosophy of theology is a branch of philosophy of science in general? The view that Popper's use of falsifiability as a criterion for demarcating the realm of science excludes theology from among the sciences rests on a common but mistaken reading of Popper. Rather Popper's criterion of demarcation merely excludes theology from among the empirical sciences. This exclusion, far from being alarming to the theologians view their discipline, accords well with it.
In Theology and the Philosophy of Science, a Wolfhart Pannenberg provides us with one approach to philosophy of theology (although he does not use that term). In that work, Pannenberg shows an uncommon familiarity with a broad range of traditions in the philosophy of science. (He does, however, misinterpret Popper in the all too common manner.) Pannenberg develops his philosophy of theology in terms of the hermeneutical tradition of philosophy of science as developed through philosophers such as Jtirgen Habermas and Hans Georg Gadamer. In the present paper I want to argue that one can also develop a philosophy of theology (to my mind, a more fruitful philosophy of theology than that developed by Pannenberg) from the general approach to philosophy of science which is found in Popper's works.
The present paper is divided into three parts. Part 1 will attempt to clear up the misinterpretation of Popper's general philosophy of science which, while it is not exactly rare among philosophers, is notoriously common among theologians. Part 2 will lay out the task of philosophy of theology, distinguishing it from philosophy