"You're not black, or gay, or Hispanic, or whatever; you wouldn't understand." Only outsiders, only the oppressed, can understand the hurt, so only they can really comprehend the need for restrictions on debate. White males have no standing to protest controls, because they haven't felt the pain.
That argument deserves a special place in the hall of shame. For one thing, it assumes that only members of certified minority groups know what pain is like. Much worse, though: the "only-minorities-can-understand" argument is anti-intellectualism at its most rancid. It is the age-old tribalist notion that, as Popper put it, "we think with our blood," "with our national heritage," or "with our class." White supremacists will always say that blacks shouldn't be in charge because they "can't understand" (they're too stupid), anti-Semites will say the same about Jews (too corrupt), and now, shamefully, some American minority activists are saying something similar about "in-groups" (too pampered, too blind). They are denying the very possibility of liberal science, whose premise is that knowledge is available to everyone and comes through public inquiry and criticism, not from the color of your skin or your ethnic heritage or your social class. Accept their credo, and you have a race war or a class war where liberal inquiry once was.
One of liberal science's great social advances was to reject the idea that races or tribes have perspectives. Within any racial or ethnic group you care to name, perspectives are much more different than alike. Knowing a man's color or descent tells you nothing whatever about his "perspective"; nor does it make him a bit more or less credible as a player in the game of science. No personal authority is allowed — nor any racial authority. To insist, then, on including people of various races as representatives of their "racial perspective" or "ethnic viewpoint" is to flirt with the irrationalism of Nazi science, and its distinctions between "Jewish" and "Aryan" science.
It is also to give power to ambitious and often dangerously illiberal people. Gays and blacks or women or whoever are no more in universal agreement than anyone else. When activists insist on introducing the "gay perspective" or the "black perspective" or the "women's perspective" into a curriculum or a discussion, they really mean introducing the activists' own particular opinions. Those minority activists want power and seek it by claiming to speak for a race or a gender or an ethnicity. Accept their premises, and knowledge comes in colors. Public criticism across lines of race or blood becomes difficult or impossible.
This book was written in 1992. Almost a quarter-century later, you can't stroll around the twitosphere without being jostled every few minutes by some dipshit college kid hollering about privilege and trying to stuff a pamphlet in your hand. Ah, ploosa shawnje.
To clarify, when he uses the term "liberal science", he's referring mainly to two principles. One, no one gets the final say: you may claim that a statement is established as knowledge only if it can be debunked in principle, and only insofar as it withstands attempts to debunk it. And two, no one has personal authority: you may claim that a statement has been established as knowledge only insofar as the method used to check it gives the same result regardless of the identity of the checker, and regardless of the source of the statement. These principles apply just as much in everyday life as in the laboratory. To this, he contrasts the principle of fundamentalism, which he basically defines as those who know the truth should decide who is right, a principle first established by good ol' Plato. "If you believe that truth is obvious, then it is obvious who should settle differences of opinion: those who know the truth. This is the fundamentalist way: rule by the right-thinking, exclusion and (if necessary) elimination of the wrong-thinking." Later, he adds that another characteristic is the inability to entertain the notion that you might be wrong.
I'd excerpt the whole book if I could (it's only 160 or so pages; shouldn't take you that long to read). I chose this particular passage because of the way it illuminated something you still see today — the "minority activists" he mentions in the last paragraph are often the same species of privileged white folks they spend most of their time railing against. Like religious fundamentalists, they perfunctorily acknowledge their own status as sinners but claim to have been saved by the truth nonetheless, before proceeding to lecture the heretics all the more vociferously. When challenged, it becomes obvious that they still feel entitled to set themselves up in positions of power, where they have the final say in granting recognition and validation. Minority viewpoints are only valid insofar as they harmonize with that of the privileged whites in question. You have to grudgingly admire the slick maneuvering; it's almost like if members of the Tsar's inner circle had managed to reinvent themselves as Bolshevik leaders.