Indeed the reasoned criticism of a prevailing belief is a service to the proponents of that belief; if they are incapable of defending it, they are well advised to abandon it. This self-questioning and error-correcting aspect of the scientific method is its most striking property.
Concepts which have proved useful for ordering things easily assume so great an authority over us, that we forget their terrestrial origin and accept them as unalterable facts. They then become labeled as 'conceptual necessities,' etc. The road of scientific progress is frequently blocked for long periods by such errors.
Some positive persisting fops we know, Who, if once wrong, will needs be always so; But you with pleasure own your errors past, And make each day a critique on the last.
Truths ... are too often considered as so true, that they lose all the power of truth, and lie bed-ridden in the dormitory of the soul, side by side with the most despised and exploded errors.
There is no more evil thing in this world than race prejudice, none at all. [...] It justifies and holds together more baseness, cruelty, and abomination than any other sort of error in the world.
It is not to everyone's taste that truth should be pronounced pleasant. But at least let no one believe that error becomes truth when it is pronounced unpleasant.
I believe that I have really found the relationship between gravitation and electricity, assuming that the Miller experiments are based on a fundamental error. Otherwise, the whole relativity theory collapses like a house of cards.
What is toleration? It is the prerogative of humanity. We are all steeped in weaknesses and errors: Let us forgive one another's follies, it is the first law of nature.
After long study and experience, I have come to the conclusion that (1) all religions are true; (2) all religions have some error in them; (3) all religions are almost as dear to me as my own Hinduism, in as much as all human beings should be as dear to one as one's own close relatives.
For truth is strong next to the Almighty. She needs no policies or stratagems or licensings to make her victorious. These are the shifts and the defences that error uses against her power.