Full Idea
If one reads of a genuine assassination, but then fails to read the reports next day which untruthfully deny the event, one probably does not know of the event. But we must conclude that knowledge has a further 'social aspect'.
Gist of Idea
If you would deny a truth if you know the full evidence, then knowledge has social aspects
Source
report of Gilbert Harman (Induction [1970], §IV) by Ernest Sosa - The Raft and the Pyramid Appx
Book Reference
'Epistemology - An Anthology', ed/tr. Sosa,E. /Kim,J. [Blackwell 2000], p.150
A Reaction
I doubt if this is enough to support an externalist account of defeasibility. Wise people don't 'know' of an event after one report. For 24 hours the Royalists thought they had won Marston Moor! You know he's dead when you see the Zapruder film.