The truth comes as conqueror only because we have lost the art of receiving it as guest.

Rabindranath Tagore in The Fourfold Way of India (1924)

“It is wise to take admissions of uncertainty seriously,” Daniel Kahneman noted, “but declarations of high confidence mainly tell you that an individual has constructed a coherent story in his mind, not necessarily that the story is true.”

Superforcasting, p. 85

"The remedy lies, indeed, partly in charity, but more largely in correct intellectual habits, in a predominant, ever-present disposition to see things as they are, and to judge them in the full light of an unbiased weighing of evidence applied to all possible constructions, accompanied by a withholding of judgment when the evidence is insufficient to justify conclusions.

I believe that one of the greatest moral reforms that lies immediately before us consists in the general introduction into social and civic life of that habit of mental procedure which is known in investigation as the method of multiple working hypotheses. "

-T. C. Chamberlin from: http://www.mantleplumes.org/WebDocuments/Chamberlin1897.pdf

It is knowledge, in general, which is pursued solely by man, and which is pursued for the sake of knowledge itself, because its acquisition is truly delightful, and is unlike the pleasures desirable from other pursuits [...] For the good cannot be brought forth, and evil cannot be avoided, except by knowledge.

Abu Rayhan al-Birūni

In my experience on this planet, anything that is both important and corruptible (without detection) is already corrupted.

Scott Adams

Does this fit with your experience? As a cynical economist, I'm pleasantly surprised at how non-corrupt grading is at U.S. colleges.

If there’s a single lesson that life teaches us, it’s that wishing doesn’t make it so. Words and thoughts don’t change anything. Language and reality are kept strictly apart—reality is tough, unyielding stuff, and it doesn’t care what you think or feel or say about it. Or it shouldn’t. You deal with it, and you get on with your life.

Little children don’t know that. Magical thinking: that’s what Freud called it. Once we learn otherwise we cease to be children. The separation of word and thing are the essential facts on which our adult lives are founded.

--Professor Fogg in The Magicians by Lev Grossman, p. 248

For superforecasters, beliefs are hypotheses to be tested, not treasures to be guarded. It would be facile to reduce superforecasting to a bumper-sticker slogan, but if I had to, that would be it.

Philip E. Tetlock in Superforecasting

Context: Brady is talking about a safari he took and the life the animals he saw were leading.

Brady: It really was very base, everything was about eating and not dying, pretty amazing.

Grey: Yeah, that is exactly what nature is, that's why we left.

-- Hello internet (link, animated)

Might be more anti-naturalist than strictly rationalist, but I think it still qualifies.

No matter how brilliant our scientist is, or how intricately he himself understands his discovery, if he fails to convey it to the scientific community in such a way that they have ready access to it and can understand it, unfortunately that community will not benefit from what he has discovered. The moral of this story is that the means by which knowledge is conveyed are every bit as important as that knowledge itself.

Barry Smith in Applied Ontology

Though evolution, as such, did encounter resistance, particularly from some religious groups, it was by no means the greatest of the difficulties the Darwinians faced. That difficulty stemmed from an idea that was more nearly Darwin’s own. All the well-known pre-Darwinian evolutionary theories—those of Lamarck, Chambers, Spencer, and the German Naturphilosophen—had taken evolution to be a goal-directed process.

The “idea” of man and of the contemporary flora and fauna was thought to have been present from the first creation of life, perhaps in the mind of God. That idea or plan had provided the direction and the guiding force to the entire evolutionary process.

For many men the abolition of that teleological kind of evolution was the most significant and least palatable of Darwin’s suggestions. The Origin of Species recognized no goal set either by God or nature.

Thomas Kuhn in The Structure of Scientific Revolutions