This chapter focuses on the importance of probability theory in Jevons’s thought. I argue that the crucial role which Jevons ascribed to probability stemmed from his religious ideas—a connection which the existing scholarship has overlooked. The importance of probability was connected to the relationship between humans, God and the universe: God had created an infinite universe, while the human mind was finite. Due to this gap between the finite human mind and the infinite universe, human knowledge was merely probable. Both natural and social scientists were cautioned that their theories could never be certain, only probable. I will explain how this view led Jevons to take probabilistic tools, such as the method of inverse probability, to be the most appropriate tools for scientific enquiry. I will also contextualise Jevons’s ideas on probability within the debate between Uniformitarians and Catastrophists, which was divided in part over the issue of divine intervention in the course of nature. Moreover, despite Jevons’s assertion that no conclusion could ever be certain, he believed that the existence of natural laws was a certain fact. I will argue that Jevons relied on the Creator to guarantee the existence of natural laws and the stability of nature.