Hans Reichenbach's Probability Logic

Any attempt to characterize Reichenbach’s approach to inductive reasoning must take into account some of the core influences that set his work apart from more traditional or standard approaches to inductive reasoning. In the case of Reichenbach, these influences are particularly important as otherwise Reichenbach’s views may be confused with others that are closely related but different in important ways. The particular influences on Reichenbach also shift the strengths and weaknesses of his views to areas different from the strengths and weaknesses of other approaches, and from the point of some other approaches Reichenbach’s views would seem quite unintelligible if not for the particular perspective he has. Reichenbach’s account of inductive reasoning is fiercely empirical. More than perhaps any other account it takes its lessons from the empirical sciences. In Reichenbach’s view, an inductive logic cannot be built up entirely from logical principles independent of experience, but must develop out of the reasoning practiced and useful to the natural sciences. This might already seem like turning the whole project of an inductive logic on its head: We want an inductive inference system built on some solid principles (whatever they may be) to guide our scientific methodology. How could an inference procedure that draws on the methodologies of science supply in any way a normative foundation for an epistemology in the sciences? For Reichenbach there are two reasons for this “inverse” approach. We will briefly sketch them here, but return with more detail later in the text: First, Reichenbach was deeply influenced by Werner Heisenberg’s results, including the uncertainty principle, that called into question whether there is a fact to the matter – and consequently whether there can be certain knowledge about – the truth of propositions specifying a particular location and velocity for an object in space and time. If there necessarily always remains residual uncertainty for such propositions (which prior to Heisenberg seemed completely innocuous or at worst subject to epistemic limitations), then – according to Reichenbach – this is reason for more general caution about the goals of induction. Maybe the conclusions any inductive logic can aim for when applied to the sciences are significantly limited. Requiring soundness of an inference – preservation of truth with certainty – may not only