Gould

In science, 'fact' can only mean 'confirmed to such a degree that it would be perverse to withhold provisional assent.' I suppose that apples might start to rise tomorrow, but the possibility does not merit equal time in physics classrooms.

I'm confused as to how people take this level of doubt or uncertainty, more or less the <1% variety, and turn it into "scientists don't know anything". Philosophically that's a valuable sort of doubt and inquisitiveness to have, but for all practical purposes it is useless for most any human being to follow to its logical conclusions. It's even worse when the public moves from a mathematical law with constants behind it into a scientific theory with repeatable and observable experimentation behind that. More or less, if you're not the expert studying and experimenting and attempting to disprove a positive theoretical assertion, don't pretend that your doubts should always be taken seriously or should determine policies, particularly for other people.

One other note. People use this 99.9% instead of 100% logic frequently with religious belief and understanding versus scientific knowledge and understanding. This is not a fair comparison. Religious belief is more like scientific hypothesis because it is not based upon empirical, repeatable, and observable truths (there are some incredibly advantageous social science understandings that religious beliefs have picked up on over the centuries, but these aren't exactly universal effects in the same way that gravity, thermodynamics, or evolution are). More to the point, a significant portion of it suffers from entirely subjective vantage points and becomes even loony and dangerous (especially where it is used to justify internalized preferences and prejudices). And without some sort of empirical truth on which to rest those loony beliefs and appeal to a more reasoned approach, there's no countering force to sort them back out of the mainstream positions. The danger of a central empirical version of truth, unassailed by testing and reasoned debate over the facts as we observe them (and ideally we can agree on these as a starting point, in practice disagreement over the facts is incredibly common), is frequently just as bad as the lack of such a central version to appeal to. Given the propensity of authorities, secular and religious, to abuse their positions and powers historically. I'm still working out how to resolve this ambiguity in such a way that we can have some trust in knowledge as it advances and still be able to appeal to it when it has some certainty behind it. Without turning it into a religion either for the people who live that way or the people who perceive it as an opposition to their current religious institutions.

Because those atheists who start writing hymns to godlessness I think are really missing the point.