No, it was a fair point, just over-optimistic in regard to absolute truth. We can't be certain that anybody believes, knows, or has even heard of, any true things. However, we're pretty good at collecting together a widely-believed set of ideas where none of those ideas conflict with any of the others so far, at least not in most people's conscious awareness apart from in the minds of a few stray dissidents who may turn out to be brilliant or wackjobs. Once in a while a popular idea is shown to conflict with the rest and we have to revise our sketchy collection of tentative theories, to keep them all in apparent agreement and hence looking true. That's rational.

Sometimes, as in physics, bashing them all into line is beyond anyone's ability, for now.