@smcder
I want to read Nagel 20 years on paper and the Kripke which were linked above.
Another way of understanding Chalmers' Hard Problem is to recognise how he aligns himself with the conceivability arguments (inverted spectra, zombie, other worlds, Jackson's Mary). I think it is very clear what he means by the Hard Problem. We are talking in these examples about qualitative phenomenal experience
non-individuated i.e. the general property of phenomenal consciousness; that mysterious qualitative experience "we all refer to as the experience of consciousness". He thinks that this is the mind-body problem—this encapsulate the mind-body problem—but it is not the mind-body problem if you explain the qualitative phenomenon of experience. When you do have that explanation, you realise the mind-body problem is the person specific nature of being not that of the qualitative phenomenal experience.
When people talk of phenomenal feeling, they talk about "the smell of a red rose" the feeling of "green" etc. They don't talk of "my feelings as a unique identity in this world of qualitative experience"
What does Chalmers mean by easy problems? basically the ones that can be objectively measured by science: correlations between phenomenal feelings and ECG such that we can say ECG pattern (mathematically translated) = feeling blue etc. He is talking about the natural sciences and the kinds of progress they make. He is saying that a fundamental shift is required that science is incapable of making namely, the shift into the world of qualitative phenomena.
@smcder
you say:
"Q2 physiological mechanisms evolved by natural selection
Q3?
By the way -- tell me what happens on or before Q21?"
On or before Q21, you probably fall asleep! or jump off something too high. No, we are supposed to arrive at x=phenomenal experience... or something like that. I don't have much confidence but I am enjoying the pernickety task so far.
We can't have your version of Q2 though. It is implying that natural selection is the cause; that there is a direction or purpose to Mother Nature. We can't have that.
Q2 The kinds of mechanism that have evolved because of replication (and necessary conditions as per Darwin) are exclusively physiological.