Better to remain silent and be thought a fool than to speak out and remove all doubt.

- generally attributed to Abraham Lincoln

Lower your voice and strengthen your argument.

- Lebanese proverb

New opinions are always suspected, and usually opposed, without any other reason but because they are not already common.

- John Locke

We should have a great many fewer disputes in the world if words were taken for what they are, the signs of our ideas, and not for things themselves.

- John Locke

The surest way to corrupt a youth is to instruct him to hold in higher esteem those who think alike than those who think differently.

- Friedrich Nietzsche

Whatever it be that makes us trust in ourselves that we are comparatively wise or good, so as to treat those with contempt who do not subscribe to our doctrines, or follow our party, is a proof and fruit of a self-righteous spirit. Self-righteousness can feed upon doctrines, as well as upon works; and a man may have the heart of a Pharisee, while his head is stored with orthodox notions of the unworthiness of the creature, and the riches of free grace. Yea, I would add, the best men are not wholly free from this leaven; and therefore are too apt to be pleased with such representations as hold up our adversaries to ridicule, and by consequence flatter our own superior judgments. Controversies for the most part, are so managed as to indulge rather than to repress this wrong disposition; and therefore, generally speaking, they are productive of little good. They provoke those whom they should convince, and puff up those whom they should edify. I hope your performance will savour of a spirit of true humility, and be a means of promoting it to others.

- John Newton

There is a principle of self, which dispses us to despise those who differ from us; and we are often under its influence, when we think we are only showing a becoming zeal in the cause of God.

- John Newton

We should have a great many fewer disputes in the world if words were taken for what they are, the signs of our ideas, and not for things themselves.

- John Locke

He who believes the truth least, holds onto it the most tenaciously.

- Augustine

On no occasion call yourself a philosopher, nor talk at large of your principles among the multitude, but act on your principles. For instance, at a banquet do not say how one ought to eat, but eat as you ought. Remember that Socrates had so completely got rid of the thought of display that when men came and wanted an introduction to philosophers he took them to be introduced; so patient of neglect was he. And if a discussion arise among the multitude on some principle, keep silent for the most part; for you are in great danger of blurting out some undigested thought. And when someone says to you, “You know nothing,” and you do not let it provoke you, then you know that you are really on the right road. For sheep do not bring grass to their shepherds and show them how much they have eaten, but they digest their fodder and then produce it in the form of wool and milk. Do the same yourself; instead of displaying your principles to the multitude, show them the results of the principles you have digested.

- The Manual of Epictetus - #46