Still Reading David Chalmers’ “The Conscious Mind: In Search of a Fundamental Theory” after blogging about the intro earlier.
It’s quite tough technically, as well as tough in terms of credibility. His appeals to logical possibility in his thought experiments stretch “conceivability” (and I never was very good with pure thought experiments, in the absence of physics); you can’t help feeling the problems might be inherent in the logical premises, rather than any conclusions that follow. However, to give him his due, he appreciates this and spends a good deal of space addressing every possible objection and doubt, every which way he can think of. Tedious, and I almost gave up, but I’m glad I didn’t.
His most famous thought experiment is his Zombie Twin, a variation on earlier Twin Earth ideas (watery stuff vs H2O, has “essential” connotations). In this case you are asked to accept the “logical possibility” of having a Zombie twin of yourself on a physically identical twin earth where the only difference is that the Zombie has no “subjective aspect to its consciousness” yet all its behaviours, decisions and responses being otherwise identical. The Zombie is identical to you except that its lights are out, it’s all dark inside, it knows nothing it is like to “feel like” you, subjectively.
Like the “mile-high unicycle” it stretches credulity that it could come about, and work with any natural physical history, so it may be physically impossible, but you have to concede it’s “logically possible”. (Deutsch by the way spends a good deal of time on this distinction between logical and physical possibility too, and I notice Chalmers himself has several other papers dealing with any gap between “conceivability and possibility” – interesting in its own right).
His main case is that subjective (or phenomenal) consciousness is the hard unsolved problem, as opposed to any causal, behavioural, (psychlogical) explanation of how conciousness works, which if not solved beyond dispute, is at least soluble in principle. I think he’s right there.
His other main thread is “supervenience” – roughly being dependent on, but not necessarily causally explained by. The Zombie stuff above is saying subjective (phenomenal) consciousness is not logically supervenient on the phsyical world. I like the fact he concedes that taking physics as (by definition) the most fundamental explanation of how things work in the world, consciousness must be physically supervenient on the physical world, but what he’s effectively saying that physics as it is currently known must have something missing that can reductively and logically explain subjective consciousness. I have to admit the penny hasn’t quite dropped yet on supervenience. He goes on to review all the whackier quantum consciousness theories, (even Hameroff’s pixie-dust) and for me he is right, that whilst these “may” turn out to have some relevance to the physical causal description of how psychological consciousness works, they are still not addressing the hard problem. The observer participation aspect in quantum physical outcomes is about as close as it gets, but it still doesn’t seem much like the view from the subjective side.
For me the problem he is showing is still the obvious one. “Scientific reasoning” is never going to explain subjectivity, without some new resources in addition to the logically positive objectivity of scientific reasoning, which by definition excludes subjectivity. He insists that’s not what he’s showing, but so far that’s my conclusion. Anyway, the guy’s obviously done his homework, so it seems essential to read on and absorb.
I guess the point he would agree with me is that the problem with the “hard problem of subjective consciousness” is not a mystery in the physics per se, though there may yet be something to be discovered in physics in this area, it’s an absence of the right reasoning tools and techniques generally, and perhaps specifically for explaining causation (where I need to understand his supervenience better).
Strange that Chalmers doesn’t include reference to Deutsch, I guess he must have become aware since this book however. Also don’t quite understand his objections to Dennett’s natural history views, like whatever logical and physical possibilities, any explanation has to include how it came to be. So far time is missing from Chalmers story. But there’s still time 🙂