Wednesday, October 19, 2005

Mind: Natural or Supernatural?

Today, on Qalmlea's blog, is a reference to an academic paper by John DePoe, "An Argument Why the Mind is Not a Physical Mechanism." Since a topic of a book that I am currently reading ("Darwin's Dangerous Idea" by Daniel C. Dennett) is that 'mind' is a product of physical mechanisms, I immediately found the paper (the link on Qalmlea's blog was dead) and read it. I have some issues with his arguments, but I need time (maybe this weekend) to make a coherent post about them. I do want to mention one issue though. I am not calling Mr. DePoe irrational, or a Creationist, but I have also encountered this problem in irrational Creationist arguments many times.

Sometimes a person will try to support their argument with mathematical equations. Then they claim that this proves their point, when in fact it does no such thing. This is what I mean:

"... by figuring that given (R) that our cognitive faculties are reliable, what is the probability of the following three propositions being true: that (N) metaphysical naturalism, (E) humans have cognitive faculties that have arisen through evolution, and (C) we have cognitive faculties of this sort that produce beliefs of this kind. Using Bayes’s Theorem, Plantinga expresses EAAN this way:

P(N & E & C | R) = [P(N & E & C) x P(R | N & E & C)] / P(R)

Since we believe our cognitive faculties are, in fact, reliable, P(R) is very near 1. Given the reasonable doubts expressed by Darwin and Churchland, P(R|N&E&C) is less than .5. Yet, even with a high estimation of P(N & C & E), it follows that P(N & E & C | R) is low (below .5). Consequently, Plantinga’s EAAN demonstrates that evolution cannot provide a way to assert that the mind is a rational mechanism."

I will ignore, for the moment, the specific meanings of R, N, E, and C as they are not important to my point. I will come back to them in the previously threatened post.

Here is the problem: Bayes' Theorem gives a probability, which in this case may be almost as high as .5 (according to Mr. DePoe). He then asserts that this 'low' probability "demonstrates that evolution cannot provide a way to assert that the mind is a rational mechanism." .5 is not a low probability. It is the probability of getting 'tails' on a single toss of a fair coin. But that does not matter. The argument boils down to: "Situation A exists. It is unlikely that process B caused A. Therefore, process B cannot have caused A." If you don't see the problem there, let me illustrate. This situation is fictional, the name, dollar amount and odds were arbitrarily chosen.

Emily just received a check for $100,000.00. The odds of Emily winning last week's Lottery drawing were 1:1,000,000. Therefore, Emily could not have won the Lottery.

Yes, the money could have come from somewhere else, but winning the Lottery is not ruled out.
Demonstrating that an event is unlikely does not prove that it cannot have happened.

Mr. DePoe's reference is: Alvin Plantinga, "Warrant and Proper Function" (Oxford: Oxford University Press, 1993)

Anyway, I do want to return to this topic after I have had time to compose my own arguments.


5 people have spouted off:

Qalmlea said...

Fixed the broken link. And finished reading the paper. You're right. The probability argument is useless. If I read it right (hurriedly), he is claiming a probability of 0.25 is small enough to reject the claim, but since the probabilities seemed arbitrary, it's rather useless. I followed the beginning parts, but he lost me about the time he started making arbitrary calculations.

My suspicion is that there are physical mechanisms involved, but that the system is so complicated (and likely chaotic) that you can't trace out direct causal pathways.

tom said...

I have also seen this type of thing elsewhere. I was perusing, the Seattle page in particular, and someone was using mathematics to argue that the the Bible is completely true because the prophecies were true. He was also talking about probability, but his argument was even more arbitrary and exemplified his utter lack of mathematic proficiency. I'm not sure if he meant the so-called "Bible Code" which was proved to be merely probability, or other prophecies, but it really is irrelevant. He claimed that the Bible has to be divine inspiration because otherwise it is not mathematically possible for the predictions to be correct. The post has been deleted, but his analogy to the prophecies(and mind you that he never said what prophecies) was this:
[He first stated that if he said it would rain tomorrow, he would have a 50/50 chance of being right, and if he said it would rain at 9 o'clock, he would have a 25% chance of being right]
"First I had a 50/50 chance, now perhaps I have lessened to 25% chance of being right. And suppose I further say it will start at 9:00 and end at 2:00- That reduced my chances another 50% down to 12 and a half-ish. But suppose I add 300 uncertain elements. I couldn't hit it!"
What the hell does that even mean? Obviously, this man is a complete moron. If you aren't physically ill at this point, please discontinue reading and beat yourself senseless. If you are feeling a bit queasy, then get to the toilet quickly, before you get stomach acid all over your perfectly good keyboard. said...

I dont know if I believe in the Supernatural

John said...
I do know that I don't believe in the supernatural.
10/22/05, 3:39 PM
jackal said...

FYI: Statasticians always set the cut-off probability (alpha) before doing the study. Typically, you're not going to be taken seriously if your alpha > 0.05. DePoe should only have rejected the defacto hypothesis "the mind is natural" (H_0) if the probability of seeing his findings given H_0 was less than 0.05.