In my previous post on the Libet experiments, I forgot to point out that this is exactly the kind of introspection failure that I talked about in All You Zombies, moreover one that happens in perfectly normal subjects and directly tied to volition. As far as I can see, this experiment pretty much drives a stake through the heart of any form of dualism except epiphenomenalism (e.g. Huxley's view that mental events are comparable to the steam whistle on a locomotive which contributes nothing to the driving of the engine). Does it make epiphenomenalism irresistible? I don't think so. One way out is to suppose that it is the act of introspecting itself that causes the delay between the act of volition and the awareness of the act of volition. It seems plausible to me that metacognition has a cost, and thus the very act of saying to yourself "I am deciding to push the button now, and the time on the clock is ---" on top of the actual decision to push the button introduces the delay that's being measured. As long as consciousness of the volition is related to the volition in a law-like way (an act of volition occurs if and only if it is followed by awareness of that act of volition), then I think we can still comfortably say it was a conscious act. I think if consciousness were truly epiphenomenal, then we couldn't in principle be aware of the difference between, say, choosing to kick out our leg, having someone seize our leg and move it, having a muscle spasm, and having our leg kick as a result of being struck on a nerve near the knee with a little rubber mallet. Even if an Epiphenomenalist points to the different causal chains in the four kicks, I think he owes an explanation of why if the mental state contributes nothing to future physical or mental states only one of these causal chains gives rise to it even as an epiphenomenon.
Later, when I have more time, I'll try to get to why I think epiphenomenalism and most anti-reductionism about the mind and brain is so deeply confused.
Yes, I'm pretty sure you're right about the possibility of a time cost of metacognition... it's not like we merely observe ourselves making decisions; I can tell you that I plan to decide to clap my hands three times in the next minute, and then do so.
It's been a while since I've played with philosophy of mind. In my early undergrad years, I wanted very much to be a dualist, but I more or less gave up hope that it was a tenable position.
Posted by: Jonathan Ichikawa at December 2, 2003 04:17 PM