Trash Talking

A certain amount of bellicose rhetoric must perhaps be forgiven when its only intended function is to rally the bloodthirsty faithful. Enemies of Mao Tse-Tung thought were once called "foreign reactionaries" and "imperialist running dogs." Such pronouncements did not result in the ultimate triumph of World Communism. But they did, perhaps, promote a happy feeling of camaraderie among the true believers.

So too with "junk science," a phrase that does nothing to convert skeptics, but which does communicate the speaker's membership in a certain ideological club in a way that fellow members may find reassuring. The charter members of this club make themselves known by never using the word "science" at all without the "junk" prefix, except when referring to epidemiological studies failing to show a statistically significant association between some disease and some product of Fortune 500 manufacture. If you really want to show your bona fides with these people, you'll use the phrase "junk science" to dismiss even scientific hypotheses that enjoy widespread acceptance among serious and impartial investigators -- e.g., the law of gravitation.

Or global warming.