Theory - primarily associated with, and originated by, David Hume (1711-1776) - which analyzes causation in terms of nothing but regular sequence (together, in Hume's case, with priority in time and contiguity in time and, where relevant, space).
The basic form of the theory says that one event causes another if it is followed by it and is such that events of the first kind are regularly followed by events of the second kind.
The point of the theory is to dispense with any mysterious causal necessity, and also to distinguish causal connections from logical connections: one event cannot logically necessitate another (Hume was the first to clarify this distinction).
The theory is therefore reductionist in nature, and versions of it appeal to empiricists and positivists.
Recently, however, the extent to which Hume himself adhered to the theory has come into dispute.
Also see: causal realism
J L Mackie, The Cement of the Universe (1974); sophisticated modern version reckoning to stay within the frame of the theory