"If you're looking for a mistake in a paper, look for the words obvious or obviously."

George Marshall Kay

"In order to be truly creative, you must lose the fear of being wrong"

Anonymous

"All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as self-evident."

Arthur Schopenhauer

"In the course of your work, you will from time to time encounter the situation where the facts and the theory do not coincide. In such circumstances, young gentlemen, it is my earnest advice to respect the facts."

Igor Sikorsky, Russian immigrant & airplane and helicopter designer.

"If a cage with a tiger is marked “an elephant”, don't believe to your eyes."

Koz'ma Prutkov (a nom-de-plume for four19th Century Russian writers)

"The way that most men deal with traditions … is to receive them all alike as they are delivered, without applying any critical test whatever."
 
"So little pains do the vulgar take in the investigation of truth, accepting readily the first story that comes to hand."

from the “History of the Peloponnesian War” ca. 410 BC, Thucydides

"You can fool all of the people some of the time, and some of the people all of the time, but you can't fool all of the people all of the time."

A. Lincoln

"You can fool too many of the people too much of the time."

James Thurber

"The first principle is that you must not fool yourself – and you are the easiest person to fool. So you have to be very careful about that. After you've not fooled yourself, it's easy not to fool other scientists. You just have to be honest in a conventional way after that."
    
"Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool."

Richard Feynman

"Extraordinary claims require extraordinary evidence."

Carl Sagan (1934 - 1996)

"Prefer reason to authority"

Charles Lyell

"All observations should be for or against a hypothesis"

Charles Darwin

"All epochs of thought have unconscious assumptions"

Sir Alfred North Whitehead

"The great tragedy of science – the slaying of a beautiful hypothesis by an ugly fact."

Thomas Huxley

"It is a standing vice of geophysics not to argue against unpalatable facts and arguments but simply to ignore them and carry on as if they did not exist."

Prof. Peter Fellgett, FRS, Astronomy & Geophysics, 2003

"Of experiments intended to illustrate a preconceived truth and convince people of its validity: a most venomous thing in the making of sciences; for whoever has fixed on his cause, before he has Experimented, can hardly avoid fitting his Experiment to his cause, rather than the cause to the truth of the Experiment itself."

Thomas Spratt, "History of the Royal Society", 1667

"The traditional method of confronting the student not with the problem but with the finished solution means depriving him of all excitement, to shut off the creative impulse, to reduce the adventure of mankind to a dusty heap of theorems."

Arthur Koestler

"I cannot give any scientist of any age better advice than this: the intensity of the conviction that a hypothesis is true has no bearing on whether it is true or not. The importance of the strength of our conviction is only to provide a proportionally strong incentive to find out if the hypothesis will stand up to critical examination."

Sir Peter Medawar, "Advice to a Young Scientist", 1979

"It is all too easy to derive endless strings of interesting-looking but untrue or irrelevant formulae instead of checking the validity of the initial premises."

John Ziman, "Reliable Knowledge", 1978, p. 14

"...highly speculative, or boldly generalized theories are easily formulated, and take hold of the imagination of scientist and layman alike. Such theories may acquire widespread authority, not because they are well founded and reliable but because they have no competition from other less consensual sources of knowledge or insight. Whether or not it is eventually validated by overwhelmingly convincing evidence the 'scientific picture' presented by this sort of theory is inevitably schematic and oversimplified. The danger is that its limitations will not be adequately recognized, and that it will be extrapolated recklessly into an all-embracing dogma."

John Ziman, "Reliable Knowledge", 1978, pp. 91-92

"The voluminous literature on hypothetical plumes is notable for its ingenuity in the near-total absence of constraints."

Warren Hamilton, Precamb. Res., 1998

"When anybody contradicted Einstein he thought it over, and if he was found wrong he was delighted, because he felt that he had escaped from an error, and that now he knew better than before."

Otto Robert Frisch, on Einstein

"It was a reaction from the old idea of protoplasm, a name which was a mere repository of ignorance."

J.B.S. Haldane, "Perspectives in Biochemistry", 1938

"What is known for certain is dull. I rarely plan my research; it plans me."

Max Perutz

"It takes many years of training to ignore the obvious."

The Economist on "Theories of Economic Growth"

"Whether true or false, others must judge; for the firmest conviction of the truth of a doctrine by its author, seems, alas, not to be the slightest guarantee of truth."

Charles Darwin, letter to Lyell, 25th June, 1858

"In fact, no opinion should be held with fervour. No-one holds with fervour that 7 x 8 = 56, because it is known that this is the case. Fervour is necessary only in commending an opinion which is doubtful or demonstrably false."

Voltaire, quoted by Bertrand Russell

"Great God, how can we possibly be always right and the others always wrong?"

Montesquieu, Cahiers

"We see that many assumptions used in previous hypotheses can be discarded as unnecessary. ...there is no need to locate the source of plumes in the lower mantle."

Richter & Parsons, 1975

"Every dogma must have its day."

H.G.Wells

"Convictions are more dangerous enemies of truth than lies."

Nietzsche

"There is something fascinating about science. One gets such wholesale returns of conjecture out of such trifling investment of fact."

Mark Twain, "Life on the Mississippi", 1883

"Words, as is well known, are the foes of reality."

Joseph Conrad, "Under Western Eyes", 1911