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Home > Dictionary of Science Quotations > Scientist Names Index R > Bertrand Russell Quotes > Certainty

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Bertrand Russell
(18 May 1872 - 2 Feb 1970)

Welsh mathematician, logician and philosopher known for his work in mathematical logic, but was also active in social and political campaigns, advocating pacifism and nuclear disarmament.



A habit of basing convictions upon evidence, and of giving to them only that degree or certainty which the evidence warrants, would, if it became general, cure most of the ills from which the world suffers.
— Bertrand Russell
In Bertrand Russell and Paul Edwards (ed.), 'Preface', Why I Am Not a Christian: And Other Essays on Religion and Related Subjects (1957), vi.
Science quotes on:  |  Base (117)  |  Become (815)  |  Certainty (174)  |  Conviction (98)  |  Cure (122)  |  Degree (275)  |  Evidence (248)  |  General (511)  |  Habit (168)  |  Most (1729)  |  Suffer (41)  |  Warrant (8)  |  World (1778)

All that passes for knowledge can be arranged in a hierarchy of degrees of certainty, with arithmetic and the facts of perception at the top.
— Bertrand Russell
From 'Philosophy For Laymen', collected in Unpopular Essays (1950, 1996), 39.
Science quotes on:  |  All (4107)  |  Arithmetic (139)  |  Arranged (4)  |  Certainty (174)  |  Degree (275)  |  Fact (1212)  |  Facts (553)  |  Hierarchy (17)  |  Knowledge (1536)  |  Perception (97)  |  Top (96)

Descartes, the father of modern philosophy … would never—so he assures us—have been led to construct his philosophy if he had had only one teacher, for then he would have believed what he had been told; but, finding that his professors disagreed with each other, he was forced to conclude that no existing doctrine was certain.
— Bertrand Russell
From 'Philosophy For Laymen', collected in Unpopular Essays (1950, 1996), 57.
Science quotes on:  |  Assure (15)  |  Belief (578)  |  Certain (550)  |  Certainty (174)  |  Conclude (65)  |  Construct (124)  |  Renι Descartes (81)  |  Disagreed (4)  |  Doctrine (75)  |  Existing (10)  |  Father (110)  |  Forced (3)  |  Modern (385)  |  Never (1087)  |  Other (2236)  |  Philosophy (382)  |  Professor (129)  |  Teacher (143)  |  Told (4)

I wanted certainty in the kind of way in which people want religious faith. I thought that certainty is more likely to be found in mathematics than elsewhere. But I discovered that many mathematical demonstrations, which my teachers expected me to accept, were full of fallacies, and that, if certainty were indeed discoverable in mathematics, it would be in a new field of mathematics, with more solid foundations than those that had hitherto been thought secure. But as the work proceeded, I was continually reminded of the fable about the elephant and the tortoise. Having constructed an elephant upon which the mathematical world could rest, I found the elephant tottering, and proceeded to construct a tortoise to keep the elephant from falling. But the tortoise was no more secure than the elephant, and after some twenty years of very arduous toil, I came to the conclusion that there was nothing more that I could do in the way of making mathematical knowledge indubitable.
— Bertrand Russell
In 'Reflections on my Eightieth Birthday', Portraits from Memory (1956), 54.
Science quotes on:  |  Accept (192)  |  Arduous (3)  |  Certainty (174)  |  Conclusion (255)  |  Construct (124)  |  Continual (43)  |  Demonstration (114)  |  Discover (553)  |  Do (1908)  |  Elephant (31)  |  Expect (201)  |  Fable (12)  |  Faith (203)  |  Fall (230)  |  Fallacy (31)  |  Field (365)  |  Foundation (173)  |  Indeed (323)  |  Indubitable (3)  |  Kind (557)  |  Knowledge (1536)  |  Making (300)  |  Mathematics (1333)  |  More (2559)  |  New (1217)  |  Nothing (969)  |  People (1005)  |  Proceed (129)  |  Religious (126)  |  Reminded (2)  |  Rest (281)  |  Solid (116)  |  Teacher (143)  |  Thought (954)  |  Toil (25)  |  Tortoise (10)  |  Want (497)  |  Way (1216)  |  Work (1351)  |  World (1778)  |  Year (932)

Philosophy, though unable to tell us with certainty what is the true answer to the doubts which it raises, is able to suggest many possibilities which enlarge our thoughts and free them from the tyranny of custom.
— Bertrand Russell
In 'The Value of Philosophy', The Problems of Philosophy (1912), 157.
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The demand for certainty is one which is natural to man, but is nevertheless an intellectual vice. If you take your children for a picnic on a doubtful day, they will demand a dogmatic answer as to whether it will be fine or wet, and be disappointed in you when you cannot be sure.
— Bertrand Russell
From 'Philosophy For Laymen', collected in Unpopular Essays (1950, 1996), 38. This idea may be summarized as “What men want is not knowledge, but certainty” — a widely circulated aphorism attributed to Russell, but for which Webmaster has so far found no citation. (Perhaps it is a summary, never expressed in those exact words, but if you know the primary source, please contact Webmaster.)
Science quotes on:  |  Answer (366)  |  Certainty (174)  |  Child (309)  |  Children (200)  |  Demand (123)  |  Disappoint (14)  |  Disappointed (6)  |  Dogmatic (7)  |  Doubtful (29)  |  Fine (33)  |  Intellectual (255)  |  Man (2249)  |  Natural (796)  |  Nevertheless (90)  |  Vice (40)  |  Weather (46)  |  Wet (6)  |  Will (2354)

What men want is not knowledge, but certainty.
— Bertrand Russell
Uncertain attribution. Often seen, but Webmaster has not yet found this wording in a primary source, and remains uncertain that this is an actual Russell quote. It is included here to provide this caution. Contact Webmaster if you have more information.
Science quotes on:  |  Certainty (174)  |  Knowledge (1536)  |  Want (497)

While the dogmatist is harmful, the sceptic is useless …; one is certain of knowing, the other of not knowing. What philosophy should dissipate is certainty, whether of knowledge or of ignorance. Knowledge is not so precise a concept as is commonly thought. Instead of saying ‘I know this’, we ought to say ‘I more or less know something more or less like this’. … Knowledge in practical affairs has not the certainty or the precision of arithmetic.
— Bertrand Russell
From 'Philosophy For Laymen', collected in Unpopular Essays (1950, 1996), 38-39.
Science quotes on:  |  Arithmetic (139)  |  Certain (550)  |  Certainty (174)  |  Concept (221)  |  Dissipate (8)  |  Dogmatism (15)  |  Harmful (12)  |  Ignorance (240)  |  Know (1519)  |  Knowing (137)  |  Knowledge (1536)  |  More (2559)  |  More Or Less (68)  |  Other (2236)  |  Philosophy (382)  |  Practical (200)  |  Precise (68)  |  Precision (68)  |  Say (984)  |  Sceptic (5)  |  Something (719)  |  Thought (954)  |  Useless (33)


See also:
  • 18 May - short biography, births, deaths and events on date of Russell's birth.
  • Bertrand Russell - context of quote “A process which led from the amoeba to man” - Medium image (500 x 350 px)
  • Bertrand Russell - context of quote “A process which led from the amoeba to man” - Large image (800 x 600 px)

Carl Sagan Thumbnail In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) -- Carl Sagan
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