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Author Topic:   Help Needed with an argument against ToE
Percy
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Posts: 18309
From: New Hampshire
Joined: 12-23-2000
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Message 16 of 22 (476348)
07-23-2008 7:39 AM
Reply to: Message 1 by creative-evolutionist
07-22-2008 9:12 AM


As Onifre points out in Message 5, his argument argues as much against his own position as any other, containing an inherent contradiction. If his argument is correct, then his argument is as full of baloney as he claims evolution is. But if that's true, then his argument isn't full of baloney, and so we arrive at the old reductio ad absurdum fallacy. I can't see why anything more need be said.

--Percy


This message is a reply to:
 Message 1 by creative-evolutionist, posted 07-22-2008 9:12 AM creative-evolutionist has not yet responded

    
Dr Adequate
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Posts: 16086
Joined: 07-20-2006
Member Rating: 10.0


Message 17 of 22 (476352)
07-23-2008 8:30 AM
Reply to: Message 13 by Grizz
07-22-2008 7:30 PM


I've read Plantinga's talk. Well, these philosophers aren't so much, are they?

Dear me, that was dumb.

Here's the central silly bit.

Paul is a prehistoric hominid; the exigencies of survival call for him to display tiger avoidance behavior. There will be many behaviors that are appropriate: fleeing, for example, or climbing a steep rock face, or crawling into a hole too small to admit the tiger, or leaping into a handy lake. Pick any such appropriately specific behavior B. Paul engages in B, we think, because, sensible fellow that he is, he has an aversion to being eaten and believes that B is a good means of thwarting the tiger's intentions.

But clearly this avoidance behavior could result from a thousand other belief-desire combinations: indefinitely many other belief-desire systems fit B equally well. Perhaps Paul very much likes the idea of being eaten, but when he sees a tiger, always runs off looking for a better prospect, because he thinks it unlikely that the tiger he sees will eat him. This will get his body parts in the right place so far as survival is concerned, without involving much by way of true belief. Or perhaps he thinks the tiger is a large, friendly, cuddly pussycat and wants to pet it; but he also believes that the best way to pet it is to run away from it. Or perhaps the confuses running towards it with running away from it, believing of the action that is really running away from it, that it is running towards it; or perhaps he thinks the tiger is a regularly reoccurring illusion, and hoping to keep his weight down, has formed the resolution to run a mile at top speed whenever presented with such an illusion; or perhaps he thinks he is about to take part in a 1600 meter race, wants to win, and believes the appearance of the tiger is the starting signal; or perhaps . . . . Clearly there are any number of belief-cum-desire systems that equally fit a given bit of behavior.

Trying to combine these probabilities in an appropriate way, then, it would be reasonable to suppose that the probability of R, of these creatures' cognitive systems' being reliable, is relatively low, somewhat less than 1/2.

Now return to Darwin's Doubt. The reasoning that applies to these hypothetical creatures, of course, also applies to us; so if we think the probability of R with respect to them is relatively low on N&E, we should think the same thing about the probability of R with respect to us.

And here he's arrived at a reductio ad absurdum of his own argument. Because when we see a man running from a tiger, we do in fact conclude with a very high degree of certainty (and so would Plantinga) that he wishes to avoid the tiger, rather than dwelling on the absurd supposition that "he thinks the tiger is a large, friendly, cuddly pussycat and wants to pet it; but he also believes that the best way to pet it is to run away from it". The probability of any of Plantinga's hypothetical alternatives being true, combined, is not greater than 50%, it is utterly negligible.

His speculation seems to be that one could survive, not by being reasonable, but by having delusions that cancel one another out. E.g. I see a tiger, I wish to pet it, I run away from it. I feel hungry, so I decide to kill myself by eating a cheese sandwich under the belief that cheese sandwiches are poisonous. When disease is rife, I wish to catch it, but I also believe that I'll maximize my chances of doing so by avoiding infected persons. And so forth. Yet a little introspection shows that this is not the case.

And a little thought shows that the a priori odds of such a creature evolving are very low. What are the odds of a system of irrational beliefs resulting in rational behavior? They are slim, because there are infinitely many more ways of being irrational that are not pro-survival. Plantinga's speculation requires my delusions to be fine-tuned for survival. But how would such a system evolve?

We may note that such a system of delusional belief would be "irreducibly complex", as the ID crowd say. If I have a desire to pet tigers but don't have the delusion that the best way to approach a tiger is to run away from it, I'm toast. It is hard to see how one can gradually arrive at such a system of pro-survival irrationality.

In most cases, an increase in rationality is going to be pro-survival. Plantinga can imagine a belief system where this is not the case, but it's like a pin balanced on its point: it's an unstable equilibrium in the space of ideas, and is incredibly unlikely to arise as a result of natural causes.

Edited by Dr Adequate, : No reason given.

Edited by Dr Adequate, : No reason given.


This message is a reply to:
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Replies to this message:
 Message 18 by Blue Jay, posted 07-23-2008 9:02 AM Dr Adequate has responded

  
Blue Jay
Member (Idle past 777 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 18 of 22 (476359)
07-23-2008 9:02 AM
Reply to: Message 17 by Dr Adequate
07-23-2008 8:30 AM


Hi, Dr A.

Dr Adequate writes:

In most cases, an increase in rationality is going to be pro-survival. Plantinga can imagine a belief system where this is not the case, but it's like trying a pin balanced on its point: it's an unstable equilibrium in the space of ideas, and is incredibly unlikely to arise as a result of natural causes.

I don't know anything about Plantinga, and I don't have the time or interest to read his stuff right now. But, it sounds to me like the line of reasoning he's putting forward is based on the old strawman that Darwinism is based entirely on randomness.

Of course, when you strip the capacity to think rationally from the equation, Plantinga might be surprised to know that what evolution actually presents to us is pretty much what he's suggesting.

You've heard of Zonosemata? It's a really popular study in undergraduate textbooks to show the process of experimental design. For those who don't, Zonosemata are Tephritid flies that flap their patterned wings to mimic the territorial mating displays of jumping spiders, which then scare away jumping spiders that might otherwise prey upon them.

Clearly, Zonosemata did not use an objectively rational thought process to arrive at this behavioral trait (can you imagine a fruit fly thinking to itself, "My wings look at lot like that predator's legs....hmmmm"?). Thus, the only conclusion is that the fly developed the mimicry through irrationality, or, more likely, through a lack of any sort of thought process entirely.

Reason appears to be a more efficient way to regulate responses to the world than a whole suite of irrational input-output response mechanisms, because the latter would require each stimulus-response process to be wired individually (each of which would have to individually go through the tedious process of fixation in the population over multiple generations, etc.), whereas objective rationality just requires a single pattern of observation and learning that can be adapted to most circumstances beyond those for which we already have encoded, "instinctual" behaviors.

Edited by Bluejay, : Can't go around misspelling fly names: people might think I'm a bad entomologist.


Darwin loves you.
This message is a reply to:
 Message 17 by Dr Adequate, posted 07-23-2008 8:30 AM Dr Adequate has responded

Replies to this message:
 Message 19 by Dr Adequate, posted 07-23-2008 9:39 AM Blue Jay has not yet responded

  
Dr Adequate
Member
Posts: 16086
Joined: 07-20-2006
Member Rating: 10.0


Message 19 of 22 (476363)
07-23-2008 9:39 AM
Reply to: Message 18 by Blue Jay
07-23-2008 9:02 AM


I don't know anything about Plantinga, and I don't have the time or interest to read his stuff right now. But, it sounds to me like the line of reasoning he's putting forward is based on the old strawman that Darwinism is based entirely on randomness.

No, not really. His point seems to be that there are irrational systems of thought which are pro-survival, and so genes causing the formation of these irrational belief systems would be a trait favored by natural selection.

I think we can grant him that; we can imagine someone thinking irrational thoughts such that his irrational beliefs "cancel out", as it were, with the net result that he behaves in a pro-survival way, and if such a system of thought existed, natural selection would make no distinction between this system and genuine rationality.

The objection to Plantinga's argument is that, on a fitness landscape, the genetic traits leading to the formation of such a system of thought would be represented by an incredibly thin spire rising from the bottom of an incredibly deep valley; whereas rationality is a hill rising smoothly from a plain. Plantinga's speculations require people to be mad in just the right way; whereas rationality is a matter of degree and under almost every conceivable set of circumstances any increase in rationality is pro-survival.

Hence the evolutionary expectation, contra Plantinga, is that pro-survival behavior is caused either by instinct (as you point out) or by rational thought; such a system as he postulates, where rational behavior springs from irrational thought, cannot evolve, even though we grant him that if it did, natural selection would smile upon it.

In the words of the old joke: "You can't get there from here".

Edited by Dr Adequate, : No reason given.


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Replies to this message:
 Message 20 by bluegenes, posted 07-24-2008 1:31 AM Dr Adequate has responded

  
bluegenes
Member (Idle past 556 days)
Posts: 3119
From: U.K.
Joined: 01-24-2007


Message 20 of 22 (476465)
07-24-2008 1:31 AM
Reply to: Message 19 by Dr Adequate
07-23-2008 9:39 AM


Plantinga
Dr Adequate writes:

I think we can grant him that; we can imagine someone thinking irrational thoughts such that his irrational beliefs "cancel out", as it were, with the net result that he behaves in a pro-survival way, and if such a system of thought existed, natural selection would make no distinction between this system and genuine rationality.

Ironically, not only can we grant him that, we can give a very likely example. Religion. The tendency to invent religions, including creation mythologies, and then believe them, is a very good example of human brain imperfection. Whether or not this tendency has ever conferred advantages in itself is hotly debated (because it could be a chance by-product of advantageous characteristics). However, we could think of possible advantages, like helping a social animal cope with grief (a potential killer), enabling advantageous emotional attachments between individuals of a very social species when life was often nasty, brutish and short. So we get animism and ancestor worship, and every single culture invents some sort of religion.

We can also look at the basic abilities that make it possible for us to do science, and see that those could be advantageous to hunter/gatherer ancestors. This is where I find Plantinga goes really wrong. He's not trying to disprove evolution, of course. Rather, he's trying to prove his religious belief that there is something more to the human mind than what nature, through natural selection, can produce. He fails, because there's no reason why natural selection shouldn't produce a mind that can analyse nature. Such a mind has obvious advantages.

I'm not demonstrating here that his apparent belief that the human mind has a supernatural element is false. Merely that his attempt to present an argument for that belief is spurious.

Another point that strikes me as odd about his confidence in the reliability of our mental faculties, made in the image of his God, is that he must be aware that most of the world doesn't believe in his God, but does believe in other Gods who are not Jesus. It follows then, that he should recognise the statistically provable fact that a majority of people now and throughout history hold false beliefs (whether his own religion is true or false).

How much does he get paid to philosophise, I wonder?

Here on EvC, we see those two evolved characteristics, the tendency to invent false universes, and the ability to observe and analyse the real one, in direct conflict. We're a weird species, when you think about it. :o


This message is a reply to:
 Message 19 by Dr Adequate, posted 07-23-2008 9:39 AM Dr Adequate has responded

Replies to this message:
 Message 21 by Dr Adequate, posted 07-24-2008 7:16 AM bluegenes has not yet responded

  
Dr Adequate
Member
Posts: 16086
Joined: 07-20-2006
Member Rating: 10.0


Message 21 of 22 (476483)
07-24-2008 7:16 AM
Reply to: Message 20 by bluegenes
07-24-2008 1:31 AM


Re: Plantinga
Another point that strikes me as odd about his confidence in the reliability of our mental faculties, made in the image of his God, is that he must be aware that most of the world doesn't believe in his God, but does believe in other Gods who are not Jesus. It follows then, that he should recognise the statistically provable fact that a majority of people now and throughout history hold false beliefs (whether his own religion is true or false).

"If the book and my brain are both the work of the same Infinite God, whose fault is it that the book and my brain do not agree?" - Robert Ingersoll


This message is a reply to:
 Message 20 by bluegenes, posted 07-24-2008 1:31 AM bluegenes has not yet responded

  
creative-evolutionist
Junior Member (Idle past 3803 days)
Posts: 7
Joined: 03-28-2008


Message 22 of 22 (476833)
07-26-2008 11:16 PM


Wow, so many responses. Gotta work through all that.

I don't even have to post the link to the original page, someone else found it :D


    
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