Of all difficulties which impede the progress of thought, and the formation of well-grounded opinions on life and social arrangements, the greatest i… - John Stuart Mill

The whole strength and value, then, of human judgment, depending on the one property, that it can be set right when it is wrong, reliance can be placed on it only when the means of setting it right are kept constantly at hand. In the case of any person whose judgment is really deserving of confidence, how has it become so? Because he has kept his mind open to criticism of his opinions and conduct. Because it has been his practice to listen to all that could be said against him; to profit by as much of it as was just, and expound to himself, and upon occasion to others, the fallacy of what was fallacious. Because he has felt, that the only way in which a human being can make some approach to knowing the whole of a subject, is by hearing what can be said about it by persons of every variety of opinion, and studying all modes in which it can be looked at by every character of mind. No wise man ever acquired his wisdom in any mode but this; nor is it in the nature of human intellect to become wise in any other manner. The steady habit of correcting and completing his own opinion by collating it with those of others, so far from causing doubt and hesitation in carrying it into practice, is the only stable foundation for a just reliance on it: for, being cognisant of all that can, at least obviously, be said against him, and having taken up his position against all gainsayers — knowing that he has sought for objections and difficulties, instead of avoiding them, and has shut out no light which can be thrown upon the subject from any quarter — he has a right to think his judgment better than that of any person, or any multitude, who have not gone through a similar process.

Not the violent conflict between parts of the truth, but the quiet suppression of half of it, is the formidable evil: there is always hope when people are forced to listen to both sides; it is when they attend only to one that errors harden into prejudices, and truth itself ceases to have the effect of truth, by being exaggerated into falsehood.

John Stuart Mill (20 May 1806 – 8 May 1873), English philosopher, political theorist, political economist, civil servant and Member of Parliament, was an influential liberal thinker of the 19th century whose works on liberty justified freedom of the individual in opposition to unlimited state control. He was an exponent of utilitarianism, an ethical theory developed by Jeremy Bentham, although his conception of it was very different from Bentham's. He clearly set forth the premises of the scientific method.