It is not only the sleep of reason that can engender monsters, as Goya wrote in one of his etchings. Lucid, vigilant reason, when it flows freely, is just as capable of formulating impeccable theories on the inequality of human races; justifying slavery; proving the inferiority of women, the black, or the yellow, the innate evil of the Jew; legitimizing the extermination of the heretic; and supporting conquest, colonialism, and war between nations or classes.
I went back to the previously linked essay and encountered this very good graf in it as well, although I see it now more in the light of the essay's questionable conclusions — it's part of a general build-up towards saying "Aw, reason 'n science, they ain't all that and a bag of chips, are they?" or something analogous to it.
What's alarming about statements like this is how they sit cheek-by-jowl with other statements about how an illiterate populace is all the easier to oppress. Yes, and I would argue that so is a populace that is generally ignorant of critical thinking and science as a discipline (as opposed to just a pile of facts, a slew of discoveries, or a bunch of technical innovations that resulted from the above). Doesn't matter if it's a government or a corporation that's holding the leashes; you're still clamped into one of 'em.
I know full well by now how reason alone isn't a defense against tyranny or oppression. The Jews of Łódź did not need to mount a counter-argument against the Nazis to justify resistance to them. If anything, reason works as a way to lay out an argument for those who are on the fence, rather than to change the minds of those who already have one made up.
But none of this makes reasoning a worthless or ineffectual pursuit. You might as well complain a mountain bike is not a very good rowboat.