By "metaphysics" I mean "the basis of science". I don't really consider this "philosophy" per se because it involve experimental results, paradigms, and everything to do with state of the art and previous states of the art.
You can call it 'scientific method' if you wish. It's one (large) part of reasoned skeptical enquiry, and it sets out a way of seeing and doing ─ induction, empiricism, details of method to ensure repeatability, quality checking, openness, publication, honesty.
Its justification is that it works ─ beyond argument the most successful system for advancing human knowledge about the world external to the self that we've ever had.
This applies to everything really. From "gravity", to pyramid construction, to Evolution if you are not familiar with the fundamental experiments then you don't really know what you know.
But we know about gravity, and I can't think of any sense in which "we've forgotten how we know it." On the contrary, our experience of gravity begins before we're born, I was taught its concepts at school, and have read popular science accounts to this day, including how discrepancies between our understanding of gravity and our observation of revolving galaxies has played its part in our hunt for the solution to the mystery known as "dark matter".
So what, exactly, do you say we've forgotten?
Yes, but knowledge does not automatically confer understanding. You can know that the sine equals the opposite over the hypotenuse without being able to use it in a sentence or apply it to a simple problem.
That's beside the point. Without knowledge, we can't understand objective reality. Knowledge is for checking and rechecking ─ part of scientific method is repeatability, checking that inductive conclusions are remain valid, hence are justified.
Egyptology belittles real scientists and refuse to do simple scientific testing. They prefer to "understand" ancient people through magical means. They literally understand the pyramid builders through a book of what they believe is incantation translated in terms of a culture from 1000 years later!!
But our understanding of what the mathematics of Sumer, Babylon, Egypt, Greece, India, China, achieved in ancient times has all come about by virtue of reasoned skeptical enquiry, whether in maths or in applied maths.
Every member of our species; homo omnisciencis. Everybody here has every answer. It's what we do and nobody is holier than thou than believers in science. Real scientists aren't nearly as bad.
You appear to be saying that your complaint is confined to posters here at RF, implying that you're happy with the actual proceedings of science in modern Western society. Is that right? If so, it's a pity you didn't make that clear at the outset, because to this point I've understood your argument to be with the way science is in fact practiced.
I've listed dozens over the years. It is assumed that human progress is linear. Most people even believe evolution is linear but this is anti-scientific.
I asked you
please give me an example of an erroneous axiom or definition of the kind you're speaking of.
So however many you've listed in the past is irrelevant. Please state a clear example of what you're claiming.
There are many but, of course, there is the assumption that Evolution can be understood without even a definition for consciousness.
In what way, in your view, is consciousness necessary to explain evolution?
And what definition of consciousness are you arguing for? I asked you if you're reasonably up to date with modern research into consciousness. Am I to assume from your silence that you're not?
There is an assumption that reality can be extrapolated and interpolated from what is known and even the best scientists often make this error.
It's part of scientific method to test whether any particular statement about physical reality is conditional, in order to determine what if any the required conditions are.
Please give me an example of "the best scientists" making the "error" you speak of.
We see what we believe and we think we see everything there is. We do not directly experience any reality at all.
What then do we experience through our senses, if not the world external to us, aka objective reality?
there is no logical relationship between language and reality.
I define objective reality as the world external to the self, which we know about through our senses, and from that pov I see great numbers of examples of connections between language and reality ─ for example, 'please pass me the salt'. Whereas you say you see no such relationship, which brings up the question, why on earth do you bother to post? As a way of talking to yourself?