 Hume introduces the problem of induction as part of an analysis of the notions of cause and effect. Hume worked with a picture, widespread in the early modern period, in which the mind was populated with mental entities called “ideas”. Hume thought that ultimately all our ideas could be traced back to the “impressions” of sense experience. In the simplest case, an idea enters the mind by being “copied” from the corresponding impression (T. 1.1.1.7/4). More complex ideas are then created by the combination of simple ideas (E. 2.5/19). Hume took there to be a number of relations between ideas, including the relation of causation (E. 3.2). (For more on Hume’s philosophy in general, see Morris &amp; Brown 2014).