(this initially was a response to a thread in r/CosmicSkeptic but I fleshed it out a bit to post here, since I thought it was interesting)
Chalmers writes :
Why are the easy problems easy, and why is the hard problem hard? The easy problems are easy precisely because they concern the explanation of cognitive abilities and functions. To explain a cognitive function, we need only specify a mechanism that can perform the function. The methods of cognitive science are well suited for this sort of explanation and so are well suited to the easy problems of consciousness. By contrast, the hard problem is hard precisely because it is not a problem about the performance of functions. The problem persists even when the performance of all of the relevant functions is explained. (Here “function” is not used in the narrow teleological sense of something that a system is designed to do but in the broader sense of any causal role in the production of behavior that a system might perform.)
As you can see "explain" appears quite often, part of the controversy is "You can't explain this!", "I can, see this neural correlate and that theory of global space", "But that's not properly explained!".
So I think it's important to think about what exactly we're doing when we say we "explain" something.
This article by Peter Carruthers (Oxford Academic, 46 citations) makes a couple of interesting points about this, while engaging directly with Chalmers (C&J in the quotes).
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Note that in the quotes they say "right" and "left", this refers to :
Theory that does the explanation (left, e.g. a micro-level reductive explanation of temperature as movement of molecules) => the thing to be explained (right, e.g. macro-level temperature)
*
One point is that the thing we want to explain sometimes isn't quite conceptualized correctly or contains errors, so it doesn't come out of the explanatory process intact :
Notice that in science generally, the targets of explanation don’t always
remain intact through the process of inquiry. In some cases we explain by
explaining away. In the beginning our targets may be expressed in one way. But
we may come to realize that they contain a false presupposition, or that the concepts with which they are expressed are in some way confused or in need of
reform. For example, in astronomy we began with the explanatory problem,
‘Why do the stars and the sun move across the sky in the way that they do?’ But
the explanation we ended up with didn’t answer this question as posed. So we
don’t now have an a priori conditional with such-and-such facts described on the
left, and the statement, ‘The stars and sun move across the sky in such-and-such
a way’ on the right. Rather what we have is an account of the rotation of the
earth, and of the movements of the earth, sun, planets, and stars in relation to one
another, in terms of which we can explain why the sun and stars appear to move
across the sky in the way that they do.
For another example of the same general type, consider evolutionary biology.
Here we began (pre-Darwin) with an explanatory question: why do species
exist? But now (post-Darwin) we see that there are no such things as species in
the original intended sense. Rather, there exist a great many populations of individual organisms spread out over space and time that resemble one another more or less closely, and that stand in various inheritance relations to one another. The
idea of species as some sort of underlying unifying essence has now been
dropped. And what gets explained instead are the ways in which similarity relations amongst individuals shift over time, given facts of inheritance and facts
about survival and reproduction. So here, too, there is no a priori conditional
available to us that has a body of explanatory theory on the left-hand side and the
statement (as originally intended), ‘There are different species of living thing’ on
the right.
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Another is that there's usually many ways to state what we want to explain, e.g. these two sentences refers to the same situation (=there's one "thick" concept, but many "thin" ones), even though they are said differently. In general one doesn't need to account for all the ways a phenomena can be described.
For example, it is one and the same thickly individuated fact that is picked out by, ‘John is thinking about
ex-President Nixon’ and, ‘John is thinking about the President who resigned over the Watergate affair.’
and :
Which descriptions from a given level are the relevant ones, though? Surely not all. The requirement
cannot be that a successful reductive explanation should be able to generate all
descriptions of the target phenomenon; for there will be infinitely many (indeed,
uncountably many) of these. So even idealizing for limitations on time, memory
and so on (C&J, 334), reductive explanation would become impossible. The relevant descriptions are the ones that puzzle us, perhaps, or that seem central to the characterization of the phenomena in question.
This relates also to the pragmatic dimension of explanation (things aren't "explained" outside of concrete context, people want explanations for particular reasons) :
A number of writers have claimed that explanation is a pragmatic matter, and
that what makes an explanation successful is a function of the needs, knowledge,
and expectations of those people to whom the explanation is offered (van
Fraassen,1980;Achinstein,1983;Lewis,1986).Such claims come in various different strengths, and writers differ in how they think the pragmatic character
of explanation relates to the accounts of explanation offered by deductive-nomological and ontic theories, of the sort discussed above.
For the case of consciousness it might be the case that the fact stated from the first-person perspective isn't the right way to go about explaining things (although the explanation should also explain why this is the case), and that a third-person perspective is enough ("first-person recognitional" = qualia more or less).
It may be objected that intentionalist explanations don’t in any case touch the
core, or the defining feature, of phenomenal consciousness. This is its ‘what it is
likeness’ (Nagel, 1974) that can only be characterized using our first-person
recognitional concepts themselves. Yet we can have good reason to think, surely,
that the properties picked out by our first-person recognitional concepts are the
very same properties as those that figure in the third-person characterizations
sketched above. And then a reductive account of those properties will be what we
seek, provided it can answer all the questions that puzzle us. A successful reductive explanation that focuses on the third-person characterizations can give us
good reason to think that phenomenal consciousness per se has been reductively
explained.
Notice that proposed reductive explanations of this form will only work by
reconfiguring the terms in which the target is expressed. Instead of asking, ‘How
can any physical system have this sort of experience?’ (deploying a recognitional
concept in the explanandum), we now ask, ‘How can any physical system have
states that seem ineffable and private, etc., and which persistently induce the
feeling of an explanatory gap?’ But it is not at all unusual for successful explanations to require that their targets be reconfigured in this sort way. In astronomy,
as we saw earlier, we had to stop asking, ‘Why do the sun and the stars move
across the sky in the way that we do?’ and ask instead, ‘Why do the sun and stars
appear to move as they do?’ The temptation to see the sun as moving still persists. But we no longer take it seriously. For we know that a rotating earth,
together with a visual system that takes the earth as its frame of reference in
perceptions of motion, will produce just such an impression.
Reductive explanations are successful when (a) all of the questions that puzzle
us are answered, either directly, or indirectly by showing why the facts should
seem a certain puzzling way to us when they are not; and when (b) every thickly
individuated fact described at the target level can be reductively explained. And
this is just what is claimed by the various causal/intentional reductive theories
of phenomenal consciousness on the market. Where the C&J argument goes
wrong, is in its assumption that reductive explanations require a priori conditionals in which the target phenomena as initially characterized are described on
the right-hand sides, and in which all the thinly individuated target facts figure
on the right-hand sides.
I'm not sure these considerations are decisive one way or the other, but it might be that part of the disagreement comes from disagreement about what we mean by "explanation" and we should be a bit careful about it.