What you’re saying applies to physicalists — nobody has ever observed something purely “physical” — in the sense that physicists define it — as something mind-independent.

What you “observe” — according to physicalist neuroscientists — is a construction of your brain, the result of an unknown stimulus.

Strictly speaking, if you are a physicalist — you are claiming (on the basis of no scientific evidence) that the nature of that stimulus is essentially “physical” — that is, mind independent.

Now, we can’t observe anything mind independent, so your claim is purely theoretical.

So actually, your statement applies to you — if you want to claim anything other than what we observe (which is a brain-construction existing in conscious experience) it’s up to you to describe it and provide evidence for its existence.

I’m simply asking you to be more specific — you appear, in all your writings, to have an underlying physicalist view. So you’re claiming something exists that is, by definition, unobservable. You (and Sean Carroll, to take one more example of a physicalist) need to provide scientific evidence for the existence of such a thing.

Can you do that?