 The thesis develops an account of probability appropriate for scientific inference. It presents an argument to supplement what Reichenbach understands to be Kant’s transcendental principle of causality with a transcendental principle of probability. In Reichenbach’s reading of Kant, the “principle of causality” asserts that every event is preceded by a cause that determines it according to some universal law (see the discussion of Kant’s principle in Section 2 of the entry on  Kant and Hume on Causality).  The principle is “transcendental” because it cannot be empirically established, but is instead a precondition for the very possibility of empirical knowledge. Reichenbach’s claim is that there is a principle of probability that has an equal status: it cannot be empirically established, but it is a precondition of empirical knowledge. It states that events are governed by a probability distribution.