Sourced

• If all mankind minus one were of one opinion, and only one person were of the contrary opinion, mankind would be no more justified in silencing that one person, than he, if he had the power, would be justified in silencing mankind.
  • John Stuart Mill, On Liberty (1859)

• The peculiar evil of silencing the expression of an opinion is, that it is robbing the human race; posterity as well as the existing generation; those who dissent from the opinion, still more than those who hold it. If the opinion is right, they are deprived of the opportunity of exchanging error for truth: if wrong, they lose, what is almost as great a benefit, the clearer perception and livelier impression of truth, produced by its collision with error.
  • John Stuart Mill, On Liberty (1859)

• To refuse a hearing to an opinion, because they are sure that it is false, is to assume that their certainty is the same thing as absolute certainty. All silencing of discussion is an assumption of infallibility. Its condemnation may be allowed to rest on this common argument, not the worse for being common.
  • John Stuart Mill, On Liberty (1859)

• I agree with no man's opinion. I have some of my own.
  • Ivan Turgenev, Fathers and Sons, ch. 12

• New opinions are always suspected, and usually opposed, without any other reason but because they are not already common.
  • John Locke, Essay on the Human Understanding

• Quot homines tot sententiae: suo quoque mos.
  As many opinions as there are men; each a law to himself.
  • Terence(c.195-159 BC), Phormio, 454

• The world is governed much more by opinion than by laws. It is not the judgment of courts, but the moral judgment of individuals and masses of men, which is the wall of defense around property and life.
  • William Ellery Channing, reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 440.

• It is more true to say that our opinions depend upon our lives and habits than to say that our lives depend upon our opinions, which is only now and then true.
  • Frederick William Robertson, reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 440.

Attributed

• Everyone is entitled to his own opinion, but not his own facts.
  • Variant: Everyone is entitled to their own opinions, but they are not entitled to their own facts.
    • Quoted in Robert Sobel's review of Past Imperfect: History According to the Movies edited by Mark C. Carnes.
  • Variant: You are entitled to your own opinion, but you are not entitled to your own facts.
    • Quoted in Timothy J. Penny, Facts Are Facts, National Review September 4, 2003.
    • Ellen Hume, Tabloids, Talk Radio and the Future of News, part 4 (TOC), 1995 cites this as something Moynihan said to a "1994 electoral opponent on WNBC in New York".

Unsourced

• Loyalty to petrified opinion never yet broke a chain, or freed a human soul.
  • Mark Twain

• Its name is Public Opinion. It is held in reverence. It settles everything. Some think it is the voice of God.
  • Mark Twain

• Too often we enjoy the comfort of opinion without the discomfort of thought.
  • John F. Kennedy

• I don't ask other men's opinions. I have my own.
  • Charles Manson

• The point is not to take the world's opinion as a guiding star but to go one's way in life and working unerringly, neither depressed by failure nor seduced by applause.
  • Gustav Mahler

• The only opinion that matters is one's own.
  • Anonymous

• Opinions are like assholes; everyone's got one.
  • Dirty Harry

• If I want your opinion, I will tell it to you.
  • Anonymous

• Opinions should be formed with great caution, and changed with greater.
  • H.W. Shaw

• Do not think of knocking out another person's brains because he differs in opinion from you. It would be as rational to knock yourself on the head because you differ from yourself ten years ago.
  • Horace Mann

• He who has no opinion of his own, but depends upon the opinion and taste of others, is a slave.
  • Klopstock

• Any opinion will do to push the other fellow’s ego back into its shell!
  • Swami Raj

• To maintain an opinion because it is thine, and not because it is true, is to prefer thyself above the truth.
  • Venning

• We should always keep a corner of our heads open and free, that we may make room for the opinions of our friends. Let us have heart and head hospitality.
  • Joubert

• No liberal man would impute a charge of unsteadiness to another for having changed his opinion.
  • Cicero

• It is not only arrogant, but it is profligate, for a man to disregard the world's opinion of himself.
  • Cicero

• Who observes not that the voice of the people, yea of that people that voiced themselves the people of God, did prosecute the God of all people, with one common voice, "He is worthy to die." I will not, therefore, ambitiously beg their voices for my preferment; nor weigh my worth in that uneven balance, in which a feather of opinion shall be moment enough to turn the scales and make a light piece go current, and a current piece seem light.
  • Arthur Warwick

• In the minds of most men, the kingdom of opinion is divided into three territories,—the territory of yes, the territory of no, and a broad, unexplored middle ground of doubt.
  • James A. Garfield

• The foolish and the dead alone never change their opinion.
  • Lowell

• Public opinion, though often formed upon a wrong basis, yet generally has a strong underlying sense of justice.
  • Abraham Lincoln

• People with opinions just go around bothering each other.
  • Buddha

• People in supervising positions in investigation are supposed to give too much of their opinion and if they are wrong saying "sorry" is enough.
  • Nate River

• Man tends to treat all his opinions as principles.
  • Herbert Agar

• Opinions cannot survive if one has no chance to fight for them.
  • Thomas Mann

• When I say “everybody says so,” I mean I say so.
  • Ed Howe