Not too long ago, it would also have been quite easy to conceive of a world in which heat and motion were two separate things. Today, this is no longer conceivable.

But it is conceivable for thermodynamics to be caused by molecular motion. No part of that is (or ever was, really) inconceivable. It is inconceivable for the sense qualia of heat to be reducible to motion, but that's just another reason to believe that physicalism is wrong. The blog post you linked doesn't actually address the idea of inconceivability.

If something seems conceivable to you now, that might just be because you don't yet understand how it's actually impossible.

No, it's because there is no possible physical explanation for consciousness (whereas there are possible kinetic explanations for heat, as well as possible sonic explanations for heat, and possible magnetic explanations for heat, and so on. All these nonexistent explanations are conceivable in ways that a physical description of sense datum is not).

By stipulation, you would have typed the above sentence regardless of whether or not you were actually conscious, and hence your statement does not provide evidence either for or against the existence of consciousness.

And I do not claim that my statement is evidence that I have qualia.

This exact statement could have been emitted by a p-zombie.

See above. No one is claiming that claims of qualia prove the existence of qualia. People are claiming that the experience of qualia proves the existence of qualia.

In particular, for a piece of knowledge to have epistemic value to me (or anyone else, for that matter), I need to have some way of acquiring that knowledge.

We're not talking about whether a statement has "epistemic value to [you]" or not. We're talking about whether it's epistemically justified or not - whether it's true or not.

There exists a mysterious substance called "consciousness" that does not causally interact with anything in the physical universe.

Neither I nor Chalmers describe consciousness as a substance.

Since this substance does not causally interact with anything in the physical universe, and you are part of the physical universe, said substance does not causally interact with you.

Only if you mean "you" in the reductive physicalist sense, which I don't.

This means, among other things, that when you use your physical fingers to type on your physical keyboard the words, "we are conscious, and know this fact through direct experience of consciousness", the cause of that series of physical actions cannot be the mysterious substance called "consciousness", since (again) that substance is causally inactive. Instead, some other mysterious process in your physical brain is occurring and causing you to type those words, operating completely independently of this mysterious substance.

Of course, although physicalists believe that the exact same "some other mysterious process in your physical brain" causes us to type, they just happen to make the assertion that consciousness is identical to that other process.

Nevertheless, for some reason you appear to expect me to treat the words you type as evidence of this mysterious, causally inactive substance's existence.

As I have stated repeatedly, I don't, and if you'd taken the time to read Chalmers you'd have known this instead of writing an entirely impotent attack on his ideas. Or you could have even read what I wrote. I literally said in the parent comment,

The confusion in your post is grounded in the idea that Chalmers or I would claim that the proof for consciousness is people's claims that they are conscious. We don't (although it could be evidence for it, if we had prior expectations against p-zombie universes which talked about consciousness). The claim is that we know consciousness is real due to our experience of it.

Honestly. How deliberately obtuse could you be to write an entire attack on an idea which I explicitly rejected in the comment to which you replied. Do not waste my time like this in the future.