Why have men more teeth than women?
By reason of the abundance of heat and blood which is more in men than in women.
-- "Of the Teeth.", Aristotle
One of the mysteries behind the quote above, was why Aristotle did not simply find a near-by woman, and ask her to permit him to count her teeth
How do we know what we 'know' to be true? The difference here is of course that between 'deductive' and 'inductive' analysis
Political 'debate' and flame wars on which Linux distribution (package manager, editor, MTA, and so on ad infinitum) is better, often degenerate to deductive reasoning from a firmly held (perhaps from ideological basis, perhaps from prior experience) 'Theory'. Then one is to state a testable 'Hypothesis', and actually perform field or experimental 'Observation' to validate or disprove that hypothesis, and finally, reaching a 'Conclusion' that the Theory is supported or not. Aristotle omitted the critical stages of testing his hypothesis, and so fell into error with his assertion. Pure reason lead him astray
It is just as easy to fall into error from the inductive reasoning side. I have noted for many years now that in early February, I see newspaper reports that the groundhog ("Punxsutawney Phil") is reported as seeing his shadow (consider the hints from the Bill Murray movies, 'Caddyshack' and 'Groundhog Day'). That he sees his shadow seems to cause Winter to continue for six weeks or so
The cardinal birds also must read the newspaper and observe the shadow sighting report in timing their return to north of the Mason-Dixon Line. When the timing is right, the cardinals return to my town. It takes a week or two, but once the cardinals have reported back to the southern over-wintering havens, the robins follow them
The return of the cardinals also cause the forsythia bush out back to bloom (I suspect there is some needed chemical agent in the bird droppings). This is important because it needs to snow on the forsythia three times before it is safe to plant the vegetable garden to avoid the seedlings being frozen and killed
My chain of 'Observation' is most careful, taken over many years. A 'Pattern' emerged that I could see, and so I formed a 'Hypothesis' as to what was occurring. My 'Theory' seems to explain nature well. The 'inductive' results are of course completely wrong, untestable, and confuses co-incidence (sequentially timed events) with causation
At the end of all the back and forth about deductive and inductive methods, we have to end up at the conclusion that pure logic is but an organized way of committing error. Nothing can replace putting forth a testable hypothesis, and getting down and dirty in the data testing it to confirmation or refutation
Critical note. — Of a piece with the absurd pedagogical demand for so-called constructive criticism is the doctrine that an iconoclast is a hollow and evil fellow unless he can prove his case. Why, indeed, should he prove it? Is he judge, jury, prosecuting officer, hangman? He proves enough, indeed, when he proves by his blasphemy that this or that idol is defectively convincing — that at least one visitor to the shrine is left full of doubts. The fact is enormously significant; it indicates that instinct has somehow risen superior to the shallowness of logic, the refuge of fools. The pedant and the priest have always been the most expert of logicians — and the most diligent disseminators of nonsense and worse. The liberation of the human mind has never been furthered by such learned dunderheads; it has been furthered by gay fellows who heaved dead cats into sanctuaries and then went roistering down the highways of the world, proving to all men that doubt, after all, was safe — that the god in the sanctuary was finite in his power, and hence a fraud. One horse-laugh is worth ten thousand syllogisms. It is not only more effective; it is also vastly more intelligent.
— The American Mercury. p. 75., Henry Louis Mencken (1880-1956)
edit: two typo fixes