Book by Scottish philosopher David Hume. The Enquiry is based on the much longer Treatise on Human Nature, which, as Hume put it, ``fell still-born from the press''. In the Enquiry, Hume advances his theory of sceptical empiricism, treating such topics as divine reward and punishment, the reason of animals, and miracles. Most importantly, though, he argues that the idea of necessary causality is a human invention, and that we cannot know any kind of real necessary connection, but merely ``constant conjunction''.

According to Immanuel Kant's Prolegomena to Any Future Metaphysics, it was Hume that awoke him (Kant) from his ``dogmatic slumber''. The Critique of Pure Reason, and in fact Kant's entire Critical philosophy, is an attempt to answer Hume (as well as others, such as Leibniz, Wolff, and Descartes). In particular, Kant develops transcendental idealism in part in order to describe a means by which we might have apodictic knowledge of causal relations.