“I realized now that militancy in the best sense of the word was the only answer where the black man was concerned, that any black man who wasn't a militant in 1970 was either blind or a coward.”

This quote was instead first mentioned in a 1931 book titled “Since Calvary: An Interpretation of Christian History” by the comparative religion specialist Lewis Browne.
Disputed

Speech delivered in Birmingham, Alabama, quoted in the Christian Science Monitor, 27 October 1921, p. 2.
1920s

Playboy interview (May 1995)
Context: I believe in moderate sexual harassment guidelines. But you can't the Stalinist situation we have in America right now, where any neurotic woman can make any stupid charge and destroy a man's reputation. If there is evidence of false accusation, the accuser should be expelled. Similarly, a woman who falsely accuses a man of rape should be sent to jail. My definition of sexual harassment is specific. It is only sexual harassment — by a man or a woman — if it is quid pro quo. That is, if someone says, "You must do this or I'm going to do that" — for instance, fire you. And whereas touching is sexual harassment, speech is not. I am militant on this. Words must remain free. The solution to speech is that women must signal the level of their tolerance — women are all different. Some are very bawdy. … You must develop the verbal tools to counter offensive language. That s life. Feminism has created a privileged, white middle class of girls who claim they're victims because they want to preserve their bourgeois decorum and passivity.

" Malcolm X: Make It Plain http://www.pbs.org/wgbh/amex/malcolmx/filmmore/pt.html," from The American Experience, season 6, episode 6, PBS (first aired 26 January 1994)
Attributed

This is attributed, with an expression of doubt as to its correctness, in Mathematics, Our Great Heritage: Essays on the Nature and Cultural Significance of Mathematics (1948) by William Leonard Schaaf, p. 163; also attributed in Pi in the Sky : Counting, Thinking and Being (1992) by John D. Barrow. There are a number of similar expressions to this with various attributions, but the earliest published variants seem to be quotations of Lord Bowen:
When I hear of an 'equity' in a case like this, I am reminded of a blind man in a dark room — looking for a black hat — which isn't there.
Lord Bowen, as quoted in "Pie Powder", Being Dust from the Law Courts, Collected and Recollected on the Western Circuit, by a Circuit Tramp (1911) by John Alderson Foote; this seems to be the earliest account of any similar expression. It is mentioned by the author that this expression has become misquoted as a "black cat" rather than "black hat."
An earlier example with "hat" as a learned judge is said to have defined the metaphysician, namely, as a blind man looking for a black hat in a dark room, the hat in question not being there Edinburgh Medical Journal, Volume 3 (1898)
With his obscure and uncertain speculations as to the intimate nature and causes of things, the philosopher is likened to a 'blind man in a dark room looking for a black cat that is not there.'
William James, himself apparently quoting someone else's expression, in Some Problems of Philosophy : A Beginning of an Introduction to Philosophy (1911) Ch. 1 : Philosophy and its Critics
A blind man in a dark room seeking for a black cat — which is not there.
A definition of metaphysics attributed to Lord Bowen, as quoted in Science from an Easy Chair (1913) by Edwin Ray Lankester, p. 99
A blind man in a dark room looking for a black cat which isn't there.
A definition of metaphysics attributed to Lord Balfour, as quoted in God in Our Work: Religious Addresses (1949) by Richard Stafford Cripps, p. 72
A philosopher is a blind man in a dark room looking for a black cat that isn't there. A theologian is the man who finds it.
H. L. Mencken, as quoted in Peter's Quotations : Ideas for Our Time (1977) by Laurence J. Peter, p. 427
A metaphysician is like a blind man in a dark room, looking for a black cat — which isn't there.
Variant published in Smiles and Chuckles (1952) by B. Hagspiel
Misattributed

Song lyrics, The Freewheelin' Bob Dylan (1963), A Hard Rain's a-Gonna Fall