Full Idea
Presentism says that although there is nothing outside the present, yet there are past-tensed and future-tensed truths that do not supervene on the present, and hence do not supervene on being.
Gist of Idea
Presentism says only the present exists, so there is nothing for tensed truths to supervene on
Source
David Lewis (Armstrong on combinatorial possibility [1992], p.207)
Book Reference
Lewis,David: 'Papers in Metaphysics and Epistemology' [CUP 1999], p.207
A Reaction
Since I rather like both presentism and truth supervening on being, this observation comes as rather a devastating blow. I thought philosophy would be quite easy, but it's turning out to be rather tricky. Could tensed truths supervene on the present?
Related Idea
Idea 14405 How can a presentist explain an object's having existed? [Merricks]