Tuesday, March 30, 2010

I don't think that argument suggests what you think it suggests.

Alvin Plantinga recently made an appearance roundabout my neck of the woods. My good friend came out from grad school to see him, so I kind of had to go as well. I mean, catching up with a buddy in grad school and picking on a 77-year-old theist? How could I miss out?

I pick on Alvin because I like him. He's a lively and affable guy in person, and really quite bright - even if he thinks that entities can be defined into existence. I just happen to think he's sadly misguided, and in an innocent enough way to justify paraphrasing The Princess Bride. Anyway, the good doctor's talk was on his evolutionary argument against naturalism, a pretty decent piece of reasoning that just so happens to cut against him in the particulars. If you don't feel like clicking through, here's the Fucking Short Version:
1. The probability that human cognitive faculties are reliable1, given naturalism and evolution, is low2.
2. If we accept both naturalism and evolution, and understand premise 1, then we have a defeater for the idea that our cognitive faculties are reliable.
3. If we have a defeater for the idea that our cognitive faculties are reliable, then we have a defeater for any belief we may come to hold with those cognitive faculties (including a belief that naturalism and evolution are true).
4. Therefore, we should not believe that naturalism and evolution are true, because they are self-defeating.
Conclusion: Therefore, fucking magic!

1 - Weasel word!
2 - So what?! The Universe is a big place and rare things happen all the time.
OK, we've some unpacking to do here. As for that first premise, Plantinga leans on a quote from Patricia Churchland on the utility of truth for evolved animals: "Boiled down to essentials, a nervous system enables the organism to succeed in the four Fs: feeding, fleeing, fighting, and reproducing. ... Truth, whatever that is, definitely takes the hindmost." Plantinga uses this to develop his point by saying that natural selection can only work on behavior, not on beliefs (nevermind the fact that beliefs often inform behavior - seriously, don't mind this for now!), and therefore the truth value of this or that belief is irrelevant next to how adaptive or maladaptive the organism's behavior is.

This is, well, true. Natural selection simply can't act on what you believe independent of everything else. Plantinga goes to great pains to make this point. All other things being equal (which they never are, but still, we're ignoring that for now), the truth value of a belief is in fact irrelevant to the evolutionary process. To put his argument in more Cartesian terms,
"My evolved brain is not perfect, therefore it screws up. Because it's all I've got to work with, I might not be able to know whether it's screwing up at any given moment, because it might be screwing up right the fuck now. Therefore, I can never be 100% certain that I'm in my right mind."
I want to press Pause to let everybody know that I am with him so far. Really and truly (I just conclude that we must live with "less than 100% certainty"). Here's where things start to get real funny, though:
"Since I can never be 100% certain that I'm in my right mind, I might even be wrong about that. Because this uncertainty is self-effacing, I ought not to buy it. Therefore, I shouldn't buy the reasoning that brought me to this conclusion. Theists don't have this problem because we believe that our brains were purpose-built by God, so we can trust them."
Not joking! He says, "If my brain is evolved (i.e. not built by God), then I shouldn't trust it, even when it tells me that my brain is evolved; so I'll go with a belief system that ignores the problem of self-doubt instead." I mean, Alvin Plantinga wouldn't say that he's ignoring the problem, but that's what he does. Look, just because cars can break down doesn't mean that my car is broken down right now, and anyway you don't need to believe in Platonic Devices to avoid the uncomfortable possibility that your car might break down tomorrow. You can in fact believe something with 95% certainty and accept that one time in twenty, you'll be surprised. I mean, holy shit.

Enough cussing for the moment. I'm going to go right for premise 1 by granting it: given naturalism (i.e. not supernaturalism) and evolution (i.e. not IDiocy), the probability that my cognitive faculties are "reliable" in any strong sense is fairly low. Now, neither Plantinga nor I wish to speak of perfect reliability here; he even gives the example in his talk that if you ask five different witnesses about a car crash, you'll get five different stories (he says that their reliability is in the overwhelming agreement upon background beliefs that make their stories possible: the crash occurred on Earth and not Mars; the crash involved cars and not boats; cars drive on roads and not rainbows; blah blah blah). However, in order to achieve survivability, some reliability is necessary: bees need to apprehend reality to a degree in order to dance out directions to their cohorts, for example. So we're talking about a gradient of reliability here, really. He granted this during the Q&A session.

But then, that really gives it up, from his end. When we speak of the probability (P) of a degree of reliability (R) occurring in nature, given no supernatural input and a competitive environment, we no longer need to speak in terms of absolutes. Rather, we have freed ourselves to talk in terms of how reliable we need to be, how long we have to get there, and how lucky we're allowed to get along the way. Early on, the demand for R will be low, raising P (since lower Rs are more achievable). As time goes on, R can be refined, and in a competitive environment this will bring about ever-stricter requirements for higher Rs - so larger timescales also improve our P. Now I, for one, was born a piss-poor thinker, and I had to be educated rather heavily in the proper use of my gray matter - this education, in turn, was based on a long history of competitive educational systems in a world of scarce funding, and informed by a long tradition based on accumulating and revising knowledge.

So really, to get the R which I enjoy this very day, I only had to be born with enough R to be worked upon by something that was more or less evolved in its own right to do just that. And looking back before that in history, I mean, wow! People were nuts! They believed all sorts of crazy shit; Hell, we still do! Even within humanity, we see wild variance for R, from scientifically literate skeptics at one end to mental patients and uneducated children at the other. The reliability of our cognitive faculties is a fluid thing which can be honed or stunted; it can improve or atrophy over time.

Now comes the question, "How lucky are we allowed to get?" After all, homo sapiens is but one species among many on this teensy little rock of ours. Would it not stand to reason that at least one organism, with enough time, would develop enough cognitive reliability to improve upon it more or less exactly as we humans have in fact done? Plantinga's response was to ask, "Well, who's to say that it would be us?" Argh. I pointed out that whichever species did that would be the one to have these sorts of conversations, and then Plantinga said, "Well, maybe it's dolphins and they have the good sense not to argue about such things." Thank you, doctor. By this point, I had pretty much asked three questions, and things needed to be moved along. Ah, well. It was fun while it lasted.

This post was featured in the 52nd Humanist Symposium.


jack ralph said...

wow, just wow. so it's "i'm short-sighted and a bit deaf... therefore: god exists!"

i just wish i had his confidence.

Steve Bowen said...

I'm paraphrasing this rebuttal all over the place without citing you Nya nya... Nya Nya Nna. :)

DM said...

you little liars do nothing but antagonize...

and you try to eliminate all the dreams and hopes of humanity...

but you LOST...



Einstein puts the final nail in the coffin of atheism...




atheists deny their own life element...



D said...

*gasp!* My very own troll? Here?! Oh, I'm so excited!

(Jack & Steve, thanks for the comments!)

jemand said...

I dunno, David Markuze is a pretty promiscuous troll. You can't feel TOO special lol

Cathy S said...

[Long time since last comment, by the way.]
I agree with the ridiculous "defining god into existence" part. It reeks of magic...which is rather interesting: do theists realise that they really believe in magic?

D said...

I'm not too worried that he's trolled elsewhere before. That just means he's more experienced, right? Shouldn't that make the experience all the better for me?

Cathy S,
Ah, if only it were that easy! But you see, to hear my brother JD explain it, magic is bad while God is good, therefore God is not magic. What God does is supernatural, but it proceeds from his authority over reality, so he's really just being God and not doing any evil ol' magic.

Look, I know it's stupid, but this is one way the theistic mind is able to compartmentalize things. I don't get it, either.

Steve Bowen said...

I've caught a nasty case of DM too. Aaaaachooo!!!