Shane King wrote
But this is exactly what I mean when I say it's a popularity contest. We say Einstein is believed by most physicists.
Well, if you chuck away all the reasons anyone has for believing anything, then of course you get apparently 'foundational' problems of epistemology. WP, however, is not here to solve those problems, which may be insoluble in ultra-sceptical terms. It is here to do an honest job of compiling an encyclopedia, not to enquire itself into 'what is knowledge?' You can look in WP and find the various fates of Einstein's views about the photoelectric effect, special relativity, general relativity and the EPR paradox discussed intelligently. On the last there is some minority view discussion on the site, even though 'most physicists' think Einstein was wrong on that one.
Charles