Thursday, April 10, 2008

Academic Theater   [John Derbyshire]

Some great fireworks Wednesday morning on the Libet thread. First we got some worthy-but-dull quantitative stuff from Bill Banks (experimental psychologist) and Francesca Carota (neuroscientist).

Then John Jacobson (philosopher/information scientist) came up and described his work at creating an unbeatable rock-paper-scissors computer program, throwing out all sorts of witty and penetrating observations on free will, "folk volition" (i.e. what we rubes think volition is all about, as opposed to what it is really all about), and something called Pessimistic Indeterminism, which naturally I like the sound of. He declared his aim as being "to explain free will without exotic physics."

Which may not be easy. Physicist Daniel Sheehan (University of San Diego) gave us a physicist's account of the nature of time. Down at the quantum level, things get radically weird, we all know that. The issue here this morning was: Do brain processes partake of the weirdness?

Sheehan believes they do. He offered some arguments from physics, and some experimental results. Most startling of the latter were experiments that seemed to show presentiment. In brief: You show your suspect a blank screen. Then you randomly display a picture, either an "emotional" one, that will evoke a strong neuro-response (e.g. naked woman) or a "calm" one (e.g. seascape). Then you quickly go back to the blank screen. You are monitoring neural reactions all the time. The "emotional" pictures show a strong reaction after they are shown, of course; but they seem to show a measurably stronger reaction before being show, too.

It's possible to explain this via known quantum effects. You just have to drop some common-sense assumptions about time and causation! Sheehan argued that the explanatory power you get by bringing quantum weirdness into biology makes it worthwhile.

This "retrocausation" is very startling when you see the numbers and graphs on-screen. I thought I felt a cold breeze as the shade of J.B. Rhine flitted through the hall. (One questioner from the floor actually mentioned psychokinesis. Uh-oh.)

Then Susan Pockett of the University of Auckland (in New Zealand) came up. I don't know what it is about the antipodes, but New Zealanders and Australians seem determined to live up to their stereotype as down-to-earth, no-nonsense practical types. J.J.C. Smart, founder of "Australian Materialism," illustrates the point. This is a particularly strict style of materialism (more properly "physicalism" in today's jargon). Beliefs, desires, intentions … material, material, material, says Smart. Read his riposte to Galen Strawson in the latter's 2006 book.

In any case, Susan — a stocky, feisty-looking woman who looked quite capable of knocking down anyone who disagreed with her — poured cold water on all that had gone before. She doubted Libet's famous results, saying he'd made unjustifiable assumptions. She pooh-poohed Sheehan's quantum weirdness, arguing that there were less-strange explanations for the phenomena. She scoffed at the "presentiment" experiment, mocking its statistics (justifiably, it seemed to me).

In questions afterwards, Susan didn't give an inch. Some academic tag-wrestling broke out. ("Didn't X counter Y's criticisms?" "Yes, but then Z pointed out that …" etc., etc.) Great theater, though all very collegial and good-humored. This is what we come to academic conferences for. I love this stuff. More shortly.

04/10 08:28 AMShare