The gods did not reveal, from the beginning,/ All things to us, but in the course of time/ Through seeking we may learn and know things better./ But as for certain truth, no man has known it,/ Nor shall he know it, neither of the gods/ Nor yet of all the things of which I speak./ For even if by chance he were to utter/ The final truth, he would himself not know it: For all is but a woven web of guesses (Xenophanes, Fragments, DK, B 18;35; & 34)
Assume 1, 2:
- All observation is theory-impregnated. (Hanson’s Patterns of Discovery is a good introduction.)
- If all observation is theory-impregnated, observations cannot definitely refute scientific theories: they are conjectural.
- Therefore, if observation (conjecture A) conflicts with scientific theory (conjecture B), there is no way to justify conjecture A or B as wrong.
Surely, some times A will be wrong, other times B will be wrong. Either A or B (or both) could agree with our background knowledge (conjecture C), but that does not make A or B any more justified, since that’s pushing the regress back one more step.
If observation is repeatedly corroborated, that is no sign that it is correct (the problem of induction, natch). Even if observation is known to be correct, that does not entail the falsity of conjecture B: there could be a problem with the experimental setup (conjecture D) or an auxiliary hypothesis (conjecture E).
Maybe Democritus was on to something when he said, “We know nothing in reality; for truth lies in an abyss.” Which conjecture is refuting which? Or is everything we know (or think we know) tentative and provisional, subject to future change? A “woven web of guesses” sits fine with me.