Hypotheses non fingo
In the history of physics, hypotheses non fingo is a phrase used by Isaac Newton in the essay General Scholium, which was appended to the second edition of Philosophiae Naturalis Principia Mathematica in 1713.
Original remark
A 1999 translation of the Principia presents Newton's remark as follows:Later commentary
The 19th-century philosopher of science William Whewell qualified this statement, saying that, "it was by such a use of hypotheses, that both Newton himself and Kepler, on whose discoveries those of Newton were based, made their discoveries". Whewell stated:What is requisite is, that the hypothesis should be close to the facts, and not connected with them by other arbitrary and untried facts; and that the philosopher should be ready to resign it as soon as the facts refuse to confirm it.
Later, Imre Lakatos asserted that such a resignation should not be too rushed.