It's a good point that whether something is testable changes over time. But, in separating scientific from non-scientific claims, can we not distinguish those

It's a good point that whether something is testable changes over time. But, in separating scientific from non-scientific claims, can we not distinguish those that are in some way motivated by some limited available evidence, and which would be testable with some kind of evidence which we can describe how to get in principle (if not practically), from those that don't have any real path towards being falsified? I think roughly that Democritus probably got lucky and was essentially making a philosophical claim, and that we selectively choose to focus on the parts that were eventually found to line up with scientific results. Apparently he also believed that some atoms were hook-shaped and others eye-shaped, and though the specific texts are lost, it's hard to see how he could have arrived at that through "scientific" means. https://en.wikipedia.org/wiki/Atomism#Democritus https://en.wikipedia.org/wiki/Atomism#Democritus If you wanted to say that something with no path to being testable is "science" because in the long arc of history we can't rule out that it might eventually be testable, then one has to admit a bunch of weird stuff into "science". No one today can guarantee that 2500 years in the future someone won't figure out the technology for inter-dimensional observation, and we'll find that in the next universe up we can listen to God talking to his choir of Angels -- but the absence of such a guarantee doesn't seem like sufficient grounds for someone to say "Abrahamic monotheism is a scientific hypothesis; we just don't have the apparatus to test it out yet."