 A careful treatment of this problem therefore requires bringing into play considerations of probability theory. This makes understandable what could otherwise be seen as very strange for a theological textbook: Bolzano’s Textbook of the Science of Religion contains a section on mathematical probability theory (RW II, 39 ff.). However, also the choice of certain examples and the focus on certain methodological questions in The Theory of Science can better be understood if one sees that they are theologically motivated. Quite interesting in this respect are Bolzano’s investigations into the discovery and credibility of testimonies and into the degree of credibility of a proposition with respect to testimonies that are in favor of it as well as of testimonies against it (WL III, 555–568); he used these investigations as a basis for his theory of the divine revelation. The special treatment of proofs, “which are only to show that the probability of a proposition exceeds a given magnitude” (WL IV, 294–296), is closely connected with the topic of miracles: In order to prove that an event \(E\) is an unusual event and thus qualifies to be a miracle, one must demonstrate that the intrinsic probability of the assumption that \(E\) has not occurred is \(\gt \bfrac{1}{2}\) and therefore exceeds a certain magnitude. The specification of a particular degree of probability, however, is not required for this. Bolzano’s digression into probability theory in his Textbook of the Science of Religion and his careful use of probability theory in the discussion of miracles are obviously directed towards arguments brought forward by David Hume, although Bolzano does not mention his name in this context.