Quotations about   proof

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A time-honored concept of Anglo-Saxon justice declares that a man is innocent until proven guilty. I believe that in a democratic society a man is similarly loyal until proven disloyal. No testaments of faith, no protestations of affection for his native land, and no amount of signatures will prove a bloody thing — one way or the other — as to a man’s patriotism or lack thereof.

Rod Serling (1924-1975) American screenwriter, playwright, television producer, narrator
Speech, Moorpark College, Moorpark, California (3 Dec 1968)
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Serling had refused to sign a loyalty oath before speaking, giving up the fee for his appearance.
Added on 2-Aug-22 | Last updated 2-Aug-22
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For a truth, once established by proof, does neither gain force nor certainty by the consent of all scholars, nor lose by the general dissent.

Maimonides
Maimonides (1135-1204) Spanish Jewish philosopher, scholar, astronomer, physician [Moses ben Maimon, Rambam, רמב״ם]
Guide for the Perplexed, Part 2, ch. 15 (c. 1190) [tr. Friedlander (1885)]
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Alternate translation:

For when something has been demonstrated, the correctness of the matter is not increased and certainty regarding it is not strengthened by the consensus of all men of knowledge with regard to it. Nor could its correctness be diminished and certainty regarding it be weakened even if all the people on earth disagreed with it.
[tr. Pines (1963)]

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So when, in future times, men ask you to prove patriotism and loyalty and affection for your native land — remember that these things are not always equated with a willingness to die or to kill.

Rod Serling (1924-1975) American screenwriter, playwright, television producer, narrator
Commencement Address, Ithaca College, New York (13 May 1972)
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Those long chains composed of very simple and easy reasonings, which geometers customarily use to arrive at their most difficult demonstrations, had given me occasion to suppose that all the things which come within the scope of human knowledge are interconnected in the same way. And I thought that, provided we refrain froma ccepting anything as true which is not, and always keep to the order required for deducing one thing from another, there can be nothing too remote to be reached in the end or too well hidden to be discovered.

[Ces longues chaînes de raisons, toutes simples et faciles, dont les géomètres ont coutume de se servir pour parvenir à leurs plus difficiles démonstrations, m’avoient donné occasion de m’imaginer que toutes les choses qui peuvent tomber sous la connoissance des hommes s’entresuivent en même façon, et que, pourvu seulement qu’on s’abstienne d’en recevoir aucune pour vraie qui ne le soit, et qu’on garde toujours l’ordre qu’il faut pour les déduire les unes des autres, il n’y en peut avoir de si éloignées auxquelles enfin on ne parvienne, ni de si cachées qu’on ne découvre.]

René Descartes (1596-1650) French philosopher, mathematician
Discourse on Method [Discours de la méthode], Part 2 (1637) [tr. Cottingham, Stoothoff (1985)]
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(Source (French)). Alternate translations:

Those long chains of reasons, (though simple and easie) which the Geometricians commonly use to lead us to their most difficult demonstrations, gave me occasion to imagine, That all things which may fall under the knowledge of Men, follow one the other in the same manner, and so we doe only abstain from receiving any one for true, which is not so, and observe always the right order of deducing them one from the other, there can be none so remote, to which at last we shall not attain; nor so hid, which we shall not discover.
[Newcombe ed. (1649)]

The long chains of simple and easy reasonings by means of which geometers are accustomed to reach the conclusions of their most difficult demonstrations, had led me to imagine that all things, to the knowledge of which man is competent, are mutually connected in the same way, and that there is nothing so far removed from us as to be beyond our reach, or so hidden that we cannot discover it, provided only we abstain from accepting the false for the true, and always preserve in our thoughts the order necessary for the deduction of one truth from another.
[tr. Veitch (1850)]

Those long chains of reasoning, simple and easy as they are of which geometricians make use in order to arrive at the most difficult demonstrations, had caused me to imagine that all those things which fall under the cognizance of man might very likely be mutually related in the same fashion; and that, provided only that we abstain from receiving anything as true which is not so, and always retain the order which is necessary in order to deduce the one conclusion from the other, there can be nothing so remote that we cannot reach to it, nor to recondite that we cannot discover it.
[tr. Haldane & Ross (1911)]

These long chains of perfectly simple and easy reasonings by means of which geometers are accustomed to carry out their most difficult demonstrations had led me to fancy that everything that can fall under human knowledge forms a similar sequence; and that so long as we avoid accepting as true what it not so, and always preserve the right order for deduction of one thing from another, there can be nothing too remote to be reached in the end, or too well hidden to be discovered.
[tr. Ascombe & Geach (1971)]

Added on 21-Mar-22 | Last updated 21-Mar-22
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The Catholic Church is an institution I am bound to hold divine — but for unbelievers a proof of its divinity might be found in the fact that no merely human institution conducted with such knavish imbecility would have lasted a fortnight.

Hilaire Belloc (1870-1953) Franco-British writer, historian [Joseph Hilaire Pierre René Belloc]
Remark to William Temple
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Quoted in Robert Speaight, The Life of Hilaire Belloc (1957). Variant: "The Catholic Church is an institution I am bound to hold divine, but for unbelievers, here is proof of its divinity, that no merely human institution run with such knavish imbecility would have lasted a fortnight."
Added on 12-Jul-21 | Last updated 12-Jul-21
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There is a rumour going around that I have found god. I think is unlikely because I have enough difficulty finding my keys, and there is empirical evidence that they exist.

Terry Pratchett (1948-2015) English author
“I create gods all the time — now I think one might exist,” Daily Mail (21 Jun 2008)
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Added on 29-Jun-21 | Last updated 29-Jun-21
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What can be asserted without evidence can also be dismissed without evidence.

Christopher Hitchens (1949-2011) English intellectual, polemicist, socio-political critic
“Mommie Dearest,” Slate (20 Oct 2003)

Sometimes referred to as Hitchens' Razor. The concept is not new (consider the Latin phrase "Quod gratis asseritur, gratis negatur"), but was popularized by Hitchens in discussion of contemporary discussion of religion, including in his work God Is Not Great (2007).

While cited by a number of sources to the 2003 Slate article on the canonization of Mother Teresa, the phrase does not appear in the 2016 reprint of the article at the time she was actually declared a saint.

More information (including the original Slate text): The long history of Hitchens' Razor • Background Probability.
Added on 17-May-21 | Last updated 17-May-21
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What certainty can there be in a Philosophy which consists in as many Hypotheses as there are Phenomena to be explained. To explain all nature is too difficult a task for any one man or even for any one age. ‘Tis much better to do a little with certainty, & leave the rest for others that come after you, than to explain all things by conjecture without making sure of any thing.

Isaac Newton (1642-1727) English physicist and mathematician
Opticks, Preface (unpublished) (1703)
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Added on 1-Mar-21 | Last updated 1-Mar-21
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Bigotry and science can have no communication with each other, for science begins where bigotry and absolute certainty end. The scientist believes in proof without certainty, the bigot in certainty without proof. Let us never forget that tyranny most often springs from a fanatical faith in the absoluteness of one’s beliefs.

Ashley Montagu (1905-1999) British-American anthropologist and humanist [b. Israel Ehrenberg, a/k/a Montague Francis Ashley-Montagu]
Science and Creationism, Introduction (1984)

The second sentence is frequently (mis)quoted:
  • "Science has proof without any certainty. Creationists have certainty without any proof."
  • "Religion gives us certainty without proof; science gives us proof without certainty."
Added on 22-Feb-21 | Last updated 22-Feb-21
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As for Eisenhower himself, Welch characterized him, in words that have made the candy manufacturer famous, as “a dedicated, conscious agent of the Communist conspiracy” — a conclusion, he added, “based on an accumulation of detailed evidence so extensive and so palpable that it seems to put this conviction beyond any reasonable doubt.”

Richard Hofstadter (1916-1970) American historian and intellectual
“The Paranoid Style in American Politics,” Herbert Spencer Lecture, Oxford (Nov 1963)
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Reprinted in Harpers (Nov 1964).
Added on 16-Dec-20 | Last updated 16-Dec-20
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The path of sound credence is through the thick forest of skepticism.

George Jean Nathan (1892-1958) American editor and critic
Materia Critica, “Critic and Criticism,” sec. 4 (1924)
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Added on 14-Dec-20 | Last updated 14-Dec-20
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Newton and Descartes started to try and prove that God existed in the same way as they would try and prove something in the laboratory or with their mathematics … And when you try and mix science and religion you get bad science and bad religion. The two are doing two different things. … Science can give you a diagnosis of cancer. It can even cure your disease, but it cannot touch your grief and disappointment, nor can it help you to die well.

Karen Armstrong (b. 1944) British author, comparative religion scholar
“The Reason of Faith,” Interview with Michael Brunton, Ode (Sep-Oct 2009)
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Added on 26-Oct-20 | Last updated 26-Oct-20
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What the world wants iz good examples, not so mutch advice; advice may be wrong, but examples prove themselves.

Josh Billings (1818-1885) American humorist [pseud. of Henry Wheeler Shaw]
Everybody’s Friend, Or; Josh Billing’s Encyclopedia and Proverbial Philosophy of Wit and Humor, “Puddin and Milk” (1874)
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Added on 17-Jul-20 | Last updated 17-Jul-20
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There is nobody, in the commonwealth of learning, who does not profess himself a lover of truth, — and there is not a rational creature, that would not take it amiss, to be thought otherwise of. And yet, for all this, one may truly say, there are very few lovers of truth, for truth-sake, even amongst those who persuade themselves that they are so. How a man may know, whether he be so, in earnest, is worth inquiry; and I think, there is this one unerring mark of it, viz. the not entertaining any proposition with greater assurance than the proofs it is built on will warrant. Whoever goes beyond this measure of assent, it is plain, receives not truth in the love of it, loves not truth for truth-sake, but for some other by-end.

John Locke (1632-1704) English philosopher
An Essay Concerning Human Understanding, Book 4 “Of Knowledge and Opinion,” ch. 19 “Of Enthusiasm,” sec. 1 “Love of truth necessary” (1689)
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Added on 1-Jun-20 | Last updated 1-Jun-20
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Science is the belief in the ignorance of the experts.

Richard Feynman (1918-1988) American physicist
“What Is Science?” address, National Science Teachers Association, New York (1966)
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As to a hereafter, we have not the slightest evidence that there is any — no evidence that appeals to logic and reason. I have never seen what to me seemed an atom of proof that there is a future life. And yet — I am strongly inclined to expect one.

Mark Twain (1835-1910) American writer [pseud. of Samuel Clemens]
Quoted in Albert Bigelow Paine, Mark Twain: A Biography, Vol. 4, ch. 264 (1922)
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You mean, your statistics are facts, but my facts are just statistics.

Jonathan Lynn (b. 1943) English actor, comedy writer, director
Yes, Prime Minister, S1E3 “The Smokescreen” (23 Jan 1986) [with Anthony Jay]
Added on 11-Feb-20 | Last updated 11-Feb-20
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Maturity begins when we’re content to feel we’re right about something without feeling the necessity to prove someone else wrong.

Sydney J. Harris (1917-1986) Anglo-American columnist, journalist, author
(Attributed)

Frequently attributed to Harris, but the original source has not been found. Earliest citation I could find was in Reader's Digest (1973), where it is further credited to the Publishers-Hall Syndicate.
Added on 10-Feb-20 | Last updated 10-Feb-20
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Details that could throw doubt on your interpretation must be given, if you know them. You must do the best you can — if you know anything at all wrong, or possibly wrong — to explain it. If you make a theory, for example, and advertise it, or put it out, then you must also put down all the facts that disagree with it, as well as those that agree with it. There is also a more subtle problem. When you have put a lot of ideas together to make an elaborate theory, you want to make sure, when explaining what it fits, that those things it fits are not just the things that gave you the idea for the theory; but that the finished theory makes something else come out right, in addition. In summary, the idea is to try to give all of the information to help others to judge the value of your contribution; not just the information that leads to judgment in one particular direction or another.

Richard Feynman (1918-1988) American physicist
“Cargo Cult Science,” commencement address, California Institute of Technology (1974)
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Believe in truth. To abandon facts is to abandon freedom. If nothing is true, then no one can criticize power because there is no basis upon which to do so. If nothing is true, then all is spectacle. The biggest wallet pays for the most blinding lights.

Timothy Snyder (b. 1969) American historian, author
On Tyranny, ch. 10 (2017)
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Added on 7-Jun-18 | Last updated 7-Jun-18
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In our judgment of men, we are to beware of giving any great importance to occasional acts. By acts of occasional virtue weak men endeavour to redeem themselves in their own estimation, vain men to exalt themselves in that of mankind.

Henry Taylor (1800-1886) English dramatist, poet, bureaucrat, man of letters
The Statesman: An Ironical Treatise on the Art of Succeeding, ch. 3 (1836)
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There is only one proof of ability — action.

[Für das Können gibt es nur einen Beweis: das Tun.]

Marie von Ebner-Eschenbach (1830-1916) Austrian writer
Aphorisms [Aphorismen] [tr. Wister (1883)]
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Alt. trans.: "There is only one proof of ability: doing it."
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Anger is the common substitute for logic among those who have no evidence for what they desperately want to believe.

Isaac Asimov (1920-1992) Russian-American author, polymath, biochemist
“The Tyrannosaurus Prescription”
Added on 29-Mar-16 | Last updated 29-Mar-16
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Everyone is prejudiced in favor his own powers of discernment, and will always find an argument most convincing if it leads to the conclusion he has reached for himself; everyone must then be given something he can grasp and recognize as his own idea.

Pliny the Younger (c. 61-c. 113) Roman politician, writer [Gaius Plinius Caecilius Secundus]
Letters, Book 1, Letter 20 [tr. Radice (1963)]
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There is something wonderful in seeing a wrong-headed majority assailed by truth.

John Kenneth Galbraith (1908-2006) Canadian-American economist, diplomat, author
The Guardian (28 Jul 1989)
Added on 24-Jun-15 | Last updated 24-Jun-15
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In our reasonings concerning matter of fact, there are all imaginable degrees of assurance, from the highest certainty to the lowest species of moral evidence. A wise man, therefore, proportions his belief to the evidence. […] No testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous, than the fact, which it endeavors to establish.

David Hume (1711-1776) Scottish philosopher, economist, historian, empiricist
An Enquiry Concerning Human Understanding, Sec. 10 “Of Miracles,” Part 1 (1748)

Often given as just, "A wise man proportions his belief to the evidence."
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GEORGE: There is presumably a calendar date — a moment — when the onus of proof passed from the atheist to the believer, when, quite suddenly, secretly, the noes had it.

Tom Stoppard (b. 1937) Czech-English playwright and screenwriter
Jumpers, Act 1 (1972)
Added on 26-Sep-14 | Last updated 26-Sep-14
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Writers the most learned, the most accurate in details, and the soundest in tendency, frequently fall into a habit which can neither be cured nor pardoned — the habit of making history into the proof of their theories.

John Dalberg, Lord Acton (1834-1902) British historian
“The History of Freedom in Antiquity,” Speech, Bridgenorth Institute (28 Feb 1877)
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Added on 4-Mar-14 | Last updated 12-Feb-20
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The man of science has learned to believe in justification, not by faith, but by verification.

T. H. Huxley (1825-1895) English biologist [Thomas Henry Huxley]
“On the Advisableness of Improving Natural Knowledge” (1870)
Added on 18-Dec-13 | Last updated 18-Dec-13
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Times of trouble best discover the true worth of a man.

Thomas à Kempis (c. 1380-1471) German monk, author
The Imitation of Christ, Book 1, ch. 16 (c. 1418) [tr. L. Sherley-Price (1952)]
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Alt trans.: "The measure of every man's virtue is best revealed in time of adversity -- adversity that does not weaken a man but rather shows what he is."
Added on 5-Jun-09 | Last updated 14-Sep-16
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Extraordinary claims require extraordinary evidence.

Carl Sagan (1934-1996) American scientist and writer
Cosmos (1980)

Parallels a comment by Marcello Truzzi, "Extraordinary claims require extraordinary proof."
Added on 6-Aug-07 | Last updated 2-Aug-16
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When men have realized that time has upset many fighting faiths, they may come to believe even more than they believe the very foundations of their own conduct that the ultimate good desired is better reached by free trade in ideas — that the best test of truth is the power of the thought to get itself accepted in the competition of the market.

Oliver Wendell Holmes, Jr. (1841-1935) American jurist, Supreme Court Justice
Abrams v. United States, 250 U.S. 616, 630 (1919) [Dissent]
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Faced with the choice between changing one’s mind and proving there is no need to do so, almost everyone gets busy on the proof.

John Kenneth Galbraith (1908-2006) Canadian-American economist, diplomat, author
Economics, Peace and Laughter (1971)
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(also called "Galbraith's Law")
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I have argued flying saucers with lots of people. … I was interested in this: they keep arguing that it is possible. And that’s true. It is possible. They do not appreciate that the problem is not to demonstrate whether it’s possible or not, but whether it’s going on or not. Whether it’s probably occurring or not, not whether it could occur.

Richard Feynman (1918-1988) American physicist
The Meaning of It All (1998)
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Added on 1-Feb-04 | Last updated 10-Jan-20
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He uses statistics as a drunkard uses a lamppost — for support rather than for illumination.

Andrew Lang (1844-1912) Scottish writer, journalist, historian
(Attributed)

Original source not found, but attributed by several sources to Lang in 1937, possibly derived from a comment by A. E. Houseman. More information here.
Added on 1-Feb-04 | Last updated 23-Jun-21
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