I agree that an argument from personal incredulity is generally not a good one. But that doesn't mean we can't demonstrate that things are very unlikely to happen. E.g., there's good reason to think that perpetual motion machines are impossible.

It's also important to realize that "possible" in a colloquial sense often doesn't mean "having an non-zero chance of happening before the heat death of the universe". When people are asking whether self-driving cars are possible, they clearly are asking with implicit constraints on where, when, and how.

In that context, we can have quite a lot of information about how possible something is. E.g., Elon Musk predicted that Tesla would have one million robotaxis on the road by the end of 2020. Rodney Brooks, AI expert and iRobot founder, thinks that's impossible, and I agree. https://rodneybrooks.com/predictions-scorecard-2020-january-...

That's a tautological argument. Obviously things that happened were possible by definition, but you're not accounting for all the things that were actually impossible which never happened and will never happen.

It seems like interested and substantial arguments happen arguments happened around what might or might not 10-30 years from now. Travel to other stars once was considered no more impossible than travel other planets and living on other planets used to be considered not much harder than traveling to them. We now can actually travel to other planets and we know now how dependent on earth-gravity, how hard it is to traverse the distances between stars and so-forth.

Which is to say, no, you're simply wrong, we haven't really progressed from everything impossible to something things possible. Just as technology has progressed very unevenly, our ideas of possibility have gone from a lot of things sort-of possible to something things quite possible and other relatively more unlikely.