Full Idea
Where different effects have been found to follow from causes, which are to appearance exactly similar, all these various effects must occur to the mind in the same proportion in transferring the past to the future.
Gist of Idea
We transfer the frequency of past observations to our future predictions
Source
David Hume (Enquiry Conc Human Understanding [1748], VI.47)
Book Reference
Hume,David: 'Enquiries Conc. Human Understanding, Morals', ed/tr. Selby-Bigge/Nidditch [OUP 1975], p.58