It's a cop-out depending on your epistemological standpoint. I'm typically an empiricist so I appreciate the sentiment, but I recognize that other viewpoints of what truth and knowledge are could have merit.

I'm not a big reader on philosophy and epistemology but merely the smorgasbord of "theories of truth" presented at http://en.wikipedia.org/wiki/Truth is enough for me to shy away from asserting that "where the truth exists it is singular." I sympathize with and have held the same position, but I've seen enough to cast doubt upon my gut feelings on the matter.