 Hume’s critique of causation presents an important challenge to the PSR. In his Treatise of Human Nature (I, 3, 3) Hume considers several arguments which attempt to prove the “general maxim in philosophy, that whatever begins to exist, must have a cause” and finds all of them wanting. Hume argues that since the ideas of cause and its effect are evidently distinct, we can clearly conceive or imagine an object without its cause. He takes the separability of the two ideas to show that there is no necessary conceptual relation between the ideas of cause and effect insofar as conceiving the one without the other does not imply any contradiction or absurdity.