Traditionally, Kant's views on the issue of causality are taken to consist in his' response'in the Second Analogy to Hume's skeptical doubts. There is no doubt that Kant saw Hume as presenting some sort of skeptical challenge and that Kant felt the need to respond to this challenge. However, such a view of Kant's theory of causality provides an incomplete and distorted picture of Kant's actual position. I will argue that Kant's central and enduring concern with causality is rather to develop a novel version of what Leibniz calls influxus physicus or physical influx1 and to argue against the two causal theories2 that, along with the theory of physical influx, constitute the standard trichotomy3 popularized by Bayle: Pre-established Harmony and Occasionalism. Accordingly, Leibniz, Malebranche and Descartes are Kant's targets as much as Hume is.