Full Idea
We are to infer that a difference marks a cause just in case the difference would provide the best explanation of the contrast.
Gist of Idea
A contrasting difference is the cause if it offers the best explanation
Source
Peter Lipton (Inference to the Best Explanation (2nd) [2004], 08 'Improved')
Book Reference
Lipton,Peter: 'Inference to the Best Explanation (2nd ed)' [Routledge 2004], p.127
A Reaction
Lipton's offers this as his distinctive contribution to Mill's methods of enquiry. His point is that we draw inferences for explanatory reasons. He rests on Mill, and on contrastive explanation. It sounds rightish, but a bit optimistic.