Quotations about   logic

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The validity of an idea or action is determined not by whether it is widely believed or widely reviled but by whether it obeys the rules of logic. It is not because an argument is denounced by a majority that it is wrong nor, for those drawn to heroic defiance, that it is right.

Alain de Botton (b. 1969) Swiss-British author
The Consolations of Philosophy, ch. 1 “Consolation for Unpopularity” (2000)
Added on 28-Feb-19 | Last updated 28-Feb-19
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In short, Mort was one of those people who are more dangerous than a bag full of rattlesnakes. He was determined to discover the underlying logic behind the universe. Which was going to be hard, because there wasn’t one.

Terry Pratchett (1948-2015) English author
Mort (1987)
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Added on 23-Feb-18 | Last updated 23-Feb-18
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What is madness? To have erroneous perceptions and to reason correctly from them.

Voltaire (1694-1778) French writer [pseud. of Francois-Marie Arouet]
Philosophical Dictionary, “Madness” (1764)
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Added on 7-Nov-17 | Last updated 7-Nov-17
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If the world were a logical place, men would ride side-saddle.

Rita Mae Brown (b. 1944) American author, playwright
Sudden Death (1983)
Added on 16-Oct-17 | Last updated 16-Oct-17
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Philosophy had supplied Socrates with convictions in which he had been able to have rational, as opposed to hysterical, confidence when faced with disapproval.

Alain de Botton (b. 1969) Swiss-British author
The Consolations of Philosophy, ch. 1 “Consolations for Unpopularity” (2000)
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Added on 24-Aug-17 | Last updated 24-Aug-17
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Prejudices are what fools use for reason.

voltaire-prejudices-fool-reason-wist_info

Voltaire (1694-1778) French writer [pseud. of Francois-Marie Arouet]
(Attributed)
Added on 6-Dec-16 | Last updated 6-Dec-16
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It doesn’t have to make sense, it just has to sound like it does.

Elmore Leonard (1925-2013) American novelist and screenwriter
(Attributed)
Added on 18-Oct-16 | Last updated 18-Oct-16
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Histories make men wise; poets, witty; the mathematics, subtle; natural philosophy, deep; moral, grave; logic and rhetoric, able to contend.

Francis Bacon (1561-1626) English philosopher, scientist, author, statesman
“Of Studies,” Essays (1625)
Added on 29-Sep-16 | Last updated 29-Sep-16
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He’s suffering from Politicians’ Logic. Something must be done, this is something, therefore we must do it.

Antony Jay (b. 1930) English writer, broadcaster, director
Yes, Prime Minister, 2×05 “Power to the People” (7 Jan 1988)

Variant: "There is this great idea about the logic of a politician, along the lines of: 'Something must be done, this is something, therefore we must do it.'"
Added on 1-Aug-16 | Last updated 1-Aug-16
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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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Reasoning will never make a man correct an ill opinion, which by reasoning he never acquired.

Jonathan Swift (1667-1745) English writer and churchman
“Letter to a Young Clergyman” (9 Jan 1720)
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Added on 20-Aug-15 | Last updated 20-Aug-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."
Added on 24-Apr-15 | Last updated 24-Apr-15
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Men, as well as women, are much oftener led by their hearts than by their understandings.

Lord Chesterfield (1694-1773) English statesman, wit [Philip Dormer Stanhope]
Letter to his son (21 Jan 1748)
Added on 2-Mar-15 | Last updated 2-Mar-15
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You can’t reason someone out of an idea they weren’t reasoned into.

Sig Lines
~
Added on 16-Jan-15 | Last updated 16-Jan-15
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If the first button of one’s coat is wrongly buttoned, all the rest will be crooked.

Giordano Bruno (1548-1600) Italian philosopher
(Attributed)
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Attributed in John Emerich & Edward Dalberg, The Cambridge Modern History (1904).
Added on 8-Dec-14 | Last updated 8-Dec-14
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Reason is incompetent to answer any fundamental questions about God, or morality, or the meaning of life.

Carl L. Becker (1873-1945) American historian
The Heavenly City of the Eighteenth-Century Philosophers (1932)
Added on 2-Dec-14 | Last updated 2-Dec-14
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Rationality is not one of humanity’s strong points.

John Scalzi (b. 1969) American writer
The Ghost Brigades, ch. 5 (2006)
Added on 3-Sep-14 | Last updated 3-Sep-14
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As soon as a true thought has entered our mind, it gives a light which makes us see a crowd of other objects which we have never perceived before.

[Aussitôt qu’une pensée vraie est entrée dans notre esprit, elle jette une lumière qui nous fait voir une foule d’autres objets que nous n’apercevions pas auparavant.]

François-René de Chateaubriand (1768-1848) French writer, politican, diplomat
“Pensées, Réflexions et Maximes,” Complete Works of Chateaubriand [Oeuvres Illustrées de Chateaubriand], Vol. 3, sec. 7 (1852)
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Added on 8-Apr-14 | Last updated 8-Apr-14
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From principles is derived probability, but truth or certainty is obtained only from facts.

Jesse Olney (1798-1872) American geographer, educator, politician
In Godwin, The National Preceptor, Lesson 85 “Select Sentences,” rule #19 (1830)
Added on 27-Feb-14 | Last updated 27-Feb-14
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The great and peculiar benefit which a fair course of scientific study confers, even on those who do not follow it as a profession, is that it compels such a firm and entire faith in our mental processes, so far as their range extends, that it teaches us what this range is, and enables us to distinguish between the natural and the artificial limitations of man’s powers. And let me bid you remember that this faith does not rest upon mere testimony, however respectable, however solemnly supported. The works of science are her witness. Her age of inspiration and of miracles is not over, but beginning, and its duration will be coeval with that of the intellect of man. Nor is access to her deepest secrets restricted to a race or to a priesthood. Every man can, if he pleases, apply to the sources of all scientific knowledge directly, and verify for himself the conclusions of others. In science, faith is based solely on the assent of the intellect; and the most complete submission to ascertained truth is wholly voluntary, because it is accompanied by perfect freedom, nay, by every encouragement, to test and try that truth to the uttermost.

T. H. Huxley (1825-1895) English biologist [Thomas Henry Huxley]
“Science and Religion,” lecture (Dec 1858)
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Quoted in The Government School of Mines, The Builder (Jan 1859)
Added on 31-Jan-14 | Last updated 31-Jan-14
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Happiness is not an ideal of reason but of imagination.

Immanuel Kant (1724-1804) German philosopher
Groundwork of the Metaphysics of Morals [Grundlegung zur Metaphysik der Sitten] (1785)
Added on 9-Jan-14 | Last updated 25-Sep-15
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There is hardly any error into which men may not easily be led if they base their conduct upon reason only.

Samuel Butler (1835-1902) English novelist, satirist, scholar
Erewhon, ch. 21 (1872)
Added on 11-Jan-13 | Last updated 5-Sep-19
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The reason that truth is stranger than fiction is that fiction has to have a rational thread running through it in order to be believable, whereas reality may be totally irrational.

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

See Twain.
Added on 14-Aug-09 | Last updated 20-Jan-19
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An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it is also more nourishing.

H.L. Mencken (1880-1956) American writer and journalist [Henry Lewis Mencken]
A Little Book in C Major (1916)

He later changed this to "... concludes that it will also make better soup." (A Book of Burlesques (1924); also attributed to Chrestomathy.)
Added on 16-Nov-07 | Last updated 1-Dec-14
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What a man believes may be ascertained, not from his creed, but from the assumptions on which habitually acts.

George Bernard Shaw (1856-1950) British playwright and critic
Man and Superman, “The Revolutionist’s Handbook,” “Religion” (1903)
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Added on 9-Aug-07 | Last updated 7-Nov-17
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People generally quarrel because they cannot argue.

Gilbert Keith Chesterton (1874-1936) English journalist and writer
“The New Generations and Morality,” The Illustrated London News (9 Mar 1929)
Added on 1-Feb-04 | Last updated 21-Mar-14
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Logic is an organized way of going wrong with confidence.

Kettering - ketterings law - wist_info quote

Charles F. Kettering (1876-1958) American inventor, engineer, researcher, businessman
“Kettering’s Law,” from address before American Society of Mechanical Engineers (c. 1944)

Quoted in Heinlein, The Number of the Beast (1980).

Alternately quoted:

  • "Beware logic. Logic is an organized way to go wrong -- with confidence."
  • Logic is an organized way to go wrong with confidence. We should all know by now that a logical course is not always the right one."

Sometimes referred to "Kettering's Observation."

Cited in Food Industries magazine, vol. 16 (1944), referring to the speech being "recent" (the magazine is also referred to as Food Engineering).

This site previously incorrectly attributed the quote to Iris Murdoch.  That attribution seems to have been duplicated at some other sites, but was an error.  I have also found citations to L. Walter Lundell and Karl Popper.

Another "Kettering's Law" that is referenced is: "Parts left out cost nothing, require no maintenance, and do not fail."

Added on 1-Feb-04 | Last updated 7-Dec-15
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