“Humans were genetically inclined to be intolerant of difference. They could overcome the inclination, but it was a reality of the Human conflict that they often did not.”

Jokes and their Relation to the Cognitive Unconscious (1980)
Context: I am inclined to doubt that anything very resembling formal logic could be a good model for human reasoning. In particular, I doubt that any logic that prohibits self-reference can be adequate for psychology: no mind can have enough power — without the power to think about Thinking itself. Without Self-Reference it would seem immeasurably harder to achieve Self-Consciousness — which, so far as I can see, requires at least some capacity to reflect on what it does. If Russell shattered our hopes for making a completely reliable version of commonsense reasoning, still we can try to find the islands of "local consistency," in which naive reasoning remains correct.

The Doll (1887–1889)

On War (1832), Book 1

The Rickover Effect (1992)
Context: It is a human inclination to hope things will work out, despite evidence or doubt to the contrary. A successful manager must resist this temptation. This is particularly hard if one has invested much time and energy on a project and thus has come to feel possessive about it. Although it is not easy to admit what a person once thought correct now appears to be wrong, one must discipline himself to face the facts objectively and make the necessary changes — regardless of the consequences to himself. The man in charge must personally set the example in this respect. He must be able, in effect, to "kill his own child" if necessary and must require his subordinates to do likewise.

Source: The Margarets (2007), Chapter 32, “I Am Gretamara/On Mars” (p. 272)

Being and Nothingness (1943)

Women Can't Hear What Men Don't Say (2000)

Draft for a Statement of Human Obligation (1943)
Context: The combination of these two facts — the longing in the depth of the heart for absolute good, and the power, though only latent, of directing attention and love to a reality beyond the world and of receiving good from it — constitutes a link which attaches every man without exception to that other reality.
Whoever recognizes that reality recognizes also that link. Because of it, he holds every human being without any exception as something sacred to which he is bound to show respect.
This is the only possible motive for universal respect towards all human beings. Whatever formulation of belief or disbelief a man may choose to make, if his heart inclines him to feel this respect, then he in fact also recognizes a reality other than this world's reality. Whoever in fact does not feel this respect is alien to that other reality also.