Physicalists are people who equate brain states with mental states. There are people in this category; and yet there are many people who do not hold this view. Such people hold that there is an ontological difference between phenomenological experience and the physical firing of neurons one's brain. Prima facie, this seems to be a reasonable statement; after all, how could the firing of neurons be the same as the taste of an exquisite wine or the beauty of a dazzling sunset? This claim that there is a difference between "mental" states and brain (physical) states seems problematic to me after reflecting on it further.
It occurred to me that in order to make such a claim, one would have to know what both feel like. In other words, I can only distinguish between A and B if I know what A and B are. Just think about that for a moment.
Imagine a person asked you to compare an object, say, a banana, to another object, but he didn't tell you what the second object was. How could you begin to make any claims about the difference between the two objects? You couldn't.
Both sides agree in that all we get in our minds is one thing: phenomenological experience. They differ in that physicalists equate mental states (phenomenological experience) to brain states (physical firing of neurons), whereas proponents of a distinction suggest they are not the same—that there is something intrinsically different between the two. They acknowledge that although mental states may originate in the brain, the end "result" of what appears before our minds is categorically different than the mere firing of neurons; some extra "step" or translation process occurred that changed the mere firing of neurons to the phenomenological experience we receive. However, as I noted above, it doesn't seem possible that someone could make any claim about the inherent qualitative difference between phenomenological experience and the firing of neurons if they've only experienced one of those things. They could only know that the firing of neurons is ontologically distinct from phenomenological experience if they've experienced both, which they don't.
It seems to me that this is a fairly glaring hole in the reasoning of those who believe there is a distinction between the two. Is there some way to remedy this setback? Ideas and/or links to arguments or literature which discusses this would be particularly helpful.