Hume’s Two Definitions of Cause

This chapter examines David Hume's two definitions of cause in the context of quantitative and qualitative research. The two definitions can be found in Hume's quotation from Enquiries Concerning Human Understanding, and Concerning the Principles of Morals: “We may define a cause to be an object followed by another, and where all the objects, similar to the first, are followed by objects similar to the second [definition 1]. Or, in other words, where, if the first object had not been, the second never would have existed [definition 2].” Hume's phrase “in other words” makes it appear as if definition 1 and definition 2 are equivalent, when in fact they represent quite different approaches. The chapter considers how Hume's definition 2, which it calls the “counterfactual definition,” and definition 1, the “constant conjunction definition,” are related to understandings of causation in the qualitative and quantitative research traditions.