Thursday, May 25, 2017

he's at it again

Dr. V once again hammers away at physicalism here, in a post that includes a link to Terry Bisson's now-classic SF short story, "They're Made Out of Meat."

In the philosophy of mind, physicalism is the notion that the mind's existence and functioning can be explained entirely by physical phenomena. An attempt to explain the mind purely through matter quickly leads to the problem of subjectivity, which is not easily explained in terms of the physical. This central difficulty, the difficulty of explaining how and why it is that subjective experience exists, is called the "hard problem" (often capitalized) of consciousness. The diametrical alternative to physicalism, seemingly embraced by Dr. V and other philosophers, is Cartesian substance dualism, which posits that there are two basic substances in this world, per the terminology of René Descartes: res cogitans (thoughts, mental phenomena) and res extensa (material things, i.e., things physically extended in space, with three dimensions). This view presents many of its own problems (e.g., how exactly is an unextended, nonphysical mind associated with or attached to a body?), but it's rational enough that some philosophers subscribe to it.

I'm a committed physicalist when it comes to mind, like 99.999% of the legitimate neuroscientific community. Their motto: the mind is what the brain does. People like Dr. V think this is arrogant tosh, and probably irrational to boot. His dualistic arguments against physicalism are fairly strong, but I've long maintained that science will continue to erode those arguments through the slow-but-steady progress it makes in fields like artificial intelligence and mind-machine interfacing. In fact, a recent article titled "Brain Implant Allows Paralyzed People to Control an Exoskeleton with Their Mind" (here) shows pretty clearly that thoughts have neural correlates. People like Dr. V have long been dismissive of this idea. "If you think of a horse," the argument goes, "then you go digging inside the brain for a horse-image, you'll never find one." What that argument is saying is that thoughts aren't material. (I debunk the horse argument here and here.) Except that they apparently are, or brain-machine interaction would be impossible. How can a machine respond to a person's intentions unless those intentions have a physical component?

True: let me concede right now that, even if thoughts are shown to have a physical component, this still doesn't prove that thoughts are entirely physical. But if we now have machines that can pick up the neural correlates for "turn right" and "turn left," how much longer will it be before we have machines that can display a flower, however fuzzily or murkily, when we think of one? A case for total physicalism is being built, brick by brick. Science is once again rolling back medieval superstition.

The article I linked to above sidesteps the hard-problem issue of subjectivity, but it highlights the now-obvious fact that neural correlates of consciousness exist (this has been shown to be true of monkeys, too). This should have been manifest from the beginning, given the mind's ability to interact with one's own physical body.

Anyway, let Dr. V continue with his dualistic fantasy if it pleases him. He's a deep and rigorous thinker, to be sure, but he's dead wrong on this issue.

1 comment:

TheBigHenry said...

Electrons and photons (i.e., particles of light) are physical entities, both of which have the additive properties of mass (or its equivalent energy) and momentum (as a consequence of the fact that every physical entity in the universe is in directed motion through spacetime). Moreover, electrons moving in the vicinity of atomic nuclei produce so-called "braking radiation" in the form of photons.

We know that the brain's activity is electro-chemical in nature. Metabolic energy drives chemical reactions that, in turn, drive electron pulses through the brain's neuronal network.

Far be it from me to presume I know the answer to that "hard problem". But I have a feeling that, ultimately, the brain's electro-chemical activity is connected to the ruminations of the mind via the production of such deceleration photons. Our "mind's eye" visualizes the images created by such photons.

I hope I live long enough to find out.