Full Idea
The main question on which I would insist is why reliable past experience should be extended to future times, and to other objects, which for ought we know, may be only in appearance similar. …No reasoning can show this.
Gist of Idea
Reason cannot show why reliable past experience should extend to future times and remote places
Source
David Hume (Enquiry Conc Human Understanding [1748], IV.II.30)
Book Reference
Hume,David: 'Enquiries Conc. Human Understanding, Morals', ed/tr. Selby-Bigge/Nidditch [OUP 1975], p.33