Full Idea
If epiphenomenalism were true, it would be a mystery how such things could be known to us.
Gist of Idea
If epiphenomenalism were true, we couldn't report consciousness
Source
Jaegwon Kim (Philosophy of Mind [1996], p.130)
Book Reference
Kim,Jaegwon: 'Philosophy of Mind' [Westview 1998], p.130
A Reaction
If a brain were asked whether it was conscious, it would presumably say 'yes', but (if epiphenomenalism were true) the cause of that would have to be brain events, and NOT information that it is conscious, which the brain could not have. Big objection.