Deflective Truth

When the establishment needs to justify unacceptable ideas, this is often achieved by shifting the focus of the discourse towards a marginally related, but undeniable truth (usually a well-recognized scientific fact, or a widely-agreed ethical principle), treating it as if the former was a necessary derivation of the latter or even as the two statements were equivalent; even if there is no actual logical derivation, the vast majority of people, being too oblivious to rigorous logical reasoning to notice the trick, will still be convinced.
The obvious intended corollary to this operation is that anyone who disagrees with the promoted idea is implicitly accused of either ignoring or denying the truth it is allegedly "based" on (hence the accusations of being "ignorant", "anti-science", "rejecting reality", and such...); this tactic therefore works simultaneously both for propaganda, and as defamation of the opposition.