You give me examples, but not the "how" involved.
That's not an evasion. I'll "guess" at the "how" since you didn't disclose it: Newtonian mechanics predicts heavier-than-air flight is possible, and this has been confirmed by repeated observations.
Yet Newtonian mechanics itself is not universally "exact" in all situations such that its predictions can be expected to be 100% correct all the time. In our 4D world, it's "good enuf for scratch" in applications involving mechanical systems. There is, however, an emerging skepticism regarding its universal applicability, especially to such important questions as consciousness and life itself.
But without universality, it can afford no certainty. The only "certainty" regarding heavier-than-air flight ultimately rests, not on the Newtonian formalism, but on consensus in observation. Which ultimately puts the burden of proof on the reliability and trustworthiness of human perception. How trustworthy is that? It may be "good enuf for scratch," but that is not sufficient to establish certainty.
How certain can we really be that our perceptions of the world actually directly and truthfully "map" to the world external to our own minds? Both Hume and Kant pointed out that this is something human beings simply cannot know. So if observation (perception) is your standand criterion for establishing "certainty," that criterion rests on something which is fundamentally unknowable in principle, simply because there is no way for us to ascertain how close a match there is between the manner in which we perceive and the object that we perceive. We take it on faith that there is a match, and that it is strong enough to constitute useful knowledge of the world. But "strong enough" and "certainty" are clearly not the same things.
IOW, we could say that most of the time, perception gets it right. But that is hardly enough to assert complete certainty.
“You give me examples, but not the “how” involved.”
The “how” has nothing to do with Newton. And it has nothing to do with repeated observations. The how has to do only with the fact that it’s been done, and it only needed to be done once.
Do you have any doubts at all that heavier than air human flight is possible?
That’s the certaintly.
Have you ever seen a plane flying. Be honest; do you doubt it was really flying?
I think you are desparate to make knowledge uncertain. I cannot imagine why, but I think it is very dangerous. Why would you object to certainty in knowledge? Certainty in knowledge doesn’t mean you know everything, or even most things, it only means there are some things you can be absolutely certain about. If that were not the case, you would really know nothing.
Hank