On Guesses (1900-1949)

"It is best to prove things by actual experiment; then you know; whereas if you depend on guessing and supposing and conjecturing, you will never get educated." (Mark Twain [Samuel L Clemens], "Eve’s Diary", 1905)

"Some things you can’t find out; but you will never know you can’t by guessing and supposing: no, you have to be patient and go on experimenting until you find out that you can’t find out. And it is delightful to have it that way, it makes the world so interesting. If there wasn’t anything to find out, it would be dull. Even trying to find out and not finding out is just as interesting as trying to find out and finding out; and I don’t know but more so." (Mark Twain [Samuel L Clemens], "Eve’s Diary", 1905)

"In the degree in which life is uneasy and troubled, fancy is stirred to frame pictures of a contrary state of things. By reading the characteristic features of any man’s castles in the air you can make a shrewd guess as to his underlying desires which are frustrated." (John Dewey, "Reconstruction in Philosophy", 1920)

"[...] unless science is to degenerate into idle guessing, the test of value of any theory must be whether it expresses with as little redundancy as possible the facts which it intended to cover." (Sir Arthur S Eddington, "Space, Time and Gravitation: An Outline of the General Relativity", 1920)

"In regions where our ignorance is great, occasional guesses are permissible." (Sir Oliver Lodge, "On the Supposed Weight and Ultimate Fate of Radiation", Philosophical Magazine Vol. 41, 1921)

"This is called the inductive method. Hypothesis, my dear young friend, establishes itself by a cumulative process: or, to use popular language, if you make the same guess often enough it ceases to be a guess and becomes a Scientific Fact." Clive S Lewis, "The Pilgrim’s Regress: An Allegorical Apology for Christianity, Reason and Romanticism", 1933)

"I think that we shall have to get accustomed to the idea that we must not look upon science as a 'body of knowledge,' but rather as a system of hypotheses; that is to say, as a system of guesses or anticipations which in principle cannot be justified, but with which we work as long as they stand up to tests, and of which we are never justified in saying that we know they are 'true' or 'more or less certain' or even 'probable’." (Karl R Popper, "The Logic of Scientific Discovery", 1934)

"Heuristic reasoning is reasoning not regarded as final and strict but as provisional and plausible only, whose purpose is to discover the solution of the present problem. We are often obliged to use heuristic reasoning. We shall attain complete certainty when we shall have obtained the complete solution, but before obtaining certainty we must often be satisfied with a more or less plausible guess. We may need the provisional before we attain the final. We need heuristic reasoning when we construct a strict proof as we need scaffolding when we erect a building." (George Pólya, "How to solve it", 1945)