Full Idea
The class of possible causes is often too big, …but if we are lucky or clever enough to find or produce a contrast where fact and foil have similar histories, most potential explanations are immediately 'cancelled out', and we have a research programme.
Gist of Idea
With too many causes, find a suitable 'foil' for contrast, and the field narrows right down
Source
Peter Lipton (Inference to the Best Explanation (2nd) [2004], 05 'A case')
Book Reference
Lipton,Peter: 'Inference to the Best Explanation (2nd ed)' [Routledge 2004], p.81
A Reaction
He has a nice example of a triumph in 19th century German epidemiology. Once you get a good hypothesis, you can set up comparisons, based on a possible fact and a good foil. Genius is spotting hypothesis and foil. Nice.
Related Idea
Idea 16816 In 'contrastive' explanation there is a fact and a foil - why that fact, rather than this foil? [Lipton]