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.
Delusions, errors and lies are like huge, gaudy vessels, the rafters of which are rotten and worm-eaten, and those who embark in them are fated to be shipwrecked.
What is this self-inside us, this silent observer, severe and speechless critic, who can terrorize us, and urge us onto futile activity, and in the end, judge us still more severely for the errors into which his own reproaches drove us?
Extemporaneous speaking should be practised [sic] and cultivated. It is the lawyer's avenue to the public. However able and faithful he may be in other respects, people are slow to bring him business if he cannot make a speech. And yet there is not a more fatal error to young lawyers than relying too much on speech-making. If any one, upon his rare powers of speaking, shall claim an exemption from the drudgery of the law, his case is a failure in advance.
A collection of errors does not make a truth: quality cannot stem from quantity – a value is not a weight. The reasons of the majority cannot be taken as good reasons.
As the strata of the earth preserve in succession the living creatures of past epochs, so the shelves of libraries preserve in succession the errors of the past and their expositions, which like the former were very lively and made a great commotion in their own age but now stand petrified and stiff in a place where only the literary palaeontologist regards them.
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 are so many errors and misstatements in that list that I won't even begin to name them. Obama was right about one thing, though - Islam has always been a part of America's story.
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.