Freethought & Rationalism Archive

show_no_mercy · 06-21-2007, 09:29 PM

Plantinga's argument seems like a very sophisticated version of

Argumentum ad logicam, where just because someone has a false premise means that their conclusion must be false. That is, in fact, false.

I can have all false premises, go through them via valid deductive inference, and arrive at a true conclusion. Just because the premises are false doesn't mean the conclusion is false.

Steven Carr · 06-22-2007, 04:26 AM

Quote:

Originally Posted by post tenebras lux

Whenever I watch the telly, my brain 'believes' it's watching a moving image ...

Why does your mind form a false belief that it is watching a moving image on TV, when the reality is that you are looking at a succession of still images?

There is a school of thought that you do not perceive reality as it really is , because your brain was evolved by natural selection.

That is one theory, popular in certain circles.

However, Plantinga would subscribe to the theory that when we watch TV, our cognituive faculties are being mislead because of the baleful effects of sin.

Only sinners can watch TV and 'see' moving images.

God designed us to perceive the reality of a succession of still images on a TV screen, but sin has cursed his design, enabling us to watch FOX like the sinners we are.

post tenebras lux · 06-22-2007, 04:47 AM

Is that what Plantinga thinks? I didn't think he was in the "T.Rex ate coconuts" box.

If you weren't joking, that is.

Oxymoron · 06-22-2007, 05:17 AM

Well I just read the wiki link. To be honest I can't stomach Plantinga, I have wasted a good many hours peeling away layers of obfuscation to get at the bullshit in the middle and I feel queasy about giving this "thinker" any more oxygen than currently gets. Still...

Quote:

To put this another way, natural selection does not directly select for true beliefs, but rather for advantageous behaviours.

As if "true" beliefs were somehow an abstract notion that only existed in minds. What makes beliefs "true" though is how well they correspond to the external world, and so there is a well-defined measure of error - the difference between the internal representation of the world and the world itself. We can view both human cognition *and* evolution as learning algorithms (in that they take a set of parameters and adjust them based on a measure of error in order to minimise that error). Viewed in this way, natural selection doesn't have to equip us with much other than the ability to learn, so all this bullshit about "true beliefs" is just, er, bullshit.

SwoleMan · 06-22-2007, 05:57 AM

I've read what I think are good refutations of the argument that the assumption that, as Plantinga puts it, P(R/N&E)>0.5 isn't warranted. But I haven't seen much discussion of the warrant in assuming that P(R/G)>0.5, where G stands for "God" or "gods". Plantinga seems to think it's a warranted assumption, but I'm not sure why I should accept this, because there are a lot of gods I can think of that aren't concerned with providing humans with reliable cognitive faculties. I think a defender of naturalism should focus on this a bit more, instead of always defending her warrant in assuming P(R/N&E)>0.5.

sambee · 06-29-2007, 04:39 PM

I agree the tiger example is not very good. However, there are two problems with assuming that true beliefs are more likely to lead to survival (which you seem to be asserting). First, the belief that truth increases survival might be there because it increases survival even if it is not true. After all thinking you are delusional is generally debilitating. Secondly, it seems plausible that belief in a spiritual reality might increase survival rates in many settings. For example, they could conceivably increase people’s dedication to the overall reproduction of a society instead personal reproduction. Or they could push allocation of resources to food, clothing, and education instead of alcohol and drugs. If there is no spiritual reality that makes the evolution lead to rational beliefs argument problematic.

Quote:

Originally Posted by RAFH

In his offering for false beliefs leading to successful behavior, there is the classic failure to distinguish between the individual and the population. Individuals may well be shaped by evolution but they are not bound by it, particularly in voluntary behavior, however evolution operates on populations, not individuals.

Given his scenarios: "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 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... Clearly there are any number of belief-cum-desire systems that equally fit a given bit of behavior.", Plantiga focuses on the behavior of individuals such as Paul. That Paul survives for the wrong reason occurs regularly in evolution, not just when Paul is an idiot who would like to be eaten but doesn't think this particular tiger will eat him and so runs away or he believes its a nice pussy but thinks the best way to pet it is to run away from it but when Paul thinks the thin ice is to pretty to walk on and so doesn't crash through and drown or when Paul feels its the wrong day to fly and doesn't jump off the cliff. Idiots such as Paul may escape their fate occasionally but not very often. Its not about a singular behavior of a singular individual that factors decisively in evolution, but the general behaviors of the general populations. Worse yet, these arguments are based on a proposed being which is very recent in its evolutionary, process, a being with beliefs which normally would have been filtered out by this point. Its only a modern man who would have such luxuries and as been noted time and again, such individuals generally do get eaten.

Once again, Plantiga bases his argument, as so many theists do, on a highly improbable conditional situation. The big 'IF' in so many theistic arguments.

I am likewise amazed someone with Plantiga's supposed reputation would make such suggestions.

Jade · 06-29-2007, 05:40 PM

Quote:

Originally Posted by sambee

I agree the tiger example is not very good. However, there are two problems with assuming that true beliefs are more likely to lead to survival (which you seem to be asserting). First, the belief that truth increases survival might be there because it increases survival even if it is not true. After all thinking you are delusional is generally debilitating. Secondly, it seems plausible that belief in a spiritual reality might increase survival rates in many settings. For example, they could conceivably increase people’s dedication to the overall reproduction of a society instead personal reproduction. Or they could push allocation of resources to food, clothing, and education instead of alcohol and drugs. If there is no spiritual reality that makes the evolution lead to rational beliefs argument problematic.

Well, you are committing the classic mistake here that Plantinga also makes: beliefs are not heritable (except perhaps for 'innate' beliefs, and there don't seem to be very many of those); and so evolution simply cannot 'work' upon beliefs. What is heritable are generalized processes for taking sensory inputs and (often in conjunction with current beliefs) generating new beliefs out of them, as well as additional processes for evaluating, refining, and improving these generalized belief formation processes. In short, belief formation systems are heritable, but not the beliefs themselves.

While it may well be true that some particular false belief might be survival enhancing, all such speculation is pointless and does nothing to undermine 'naturalism plus evolution', because specific beliefs die out with the individual that possesses them* -- only the generalized belief formation system that generated the belief can be passed on to descendants and selected for (or against) by evolutionary forces. Proponents of the EAN must speak in terms of belief formation systems, not individual beliefs. Until they do so all their arguments are vain puffery, amounting to nought....

* That is, until linguistic communication of beliefs came along; and successful communication presupposes that the communicators can all form true beliefs about --at a minimum-- their interlocutors and what they are saying.

Edit to add:
P.S., welcome to IIDB, sambee...

SwoleMan · 06-29-2007, 06:49 PM

Quote:

Originally Posted by SwoleMan

I've read what I think are good refutations of the argument that the assumption that, as Plantinga puts it, P(R/N&E)>0.5 isn't warranted. But I haven't seen much discussion of the warrant in assuming that P(R/G)>0.5, where G stands for "God" or "gods". Plantinga seems to think it's a warranted assumption, but I'm not sure why I should accept this, because there are a lot of gods I can think of that aren't concerned with providing humans with reliable cognitive faculties. I think a defender of naturalism should focus on this a bit more, instead of always defending her warrant in assuming P(R/N&E)>0.5.

I'd like to have a comment on this. Anyone?

Bobinius · 06-30-2007, 03:04 AM

Quote:

Originally Posted by SwoleMan

I've read what I think are good refutations of the argument that the assumption that, as Plantinga puts it, P(R/N&E)>0.5 isn't warranted. But I haven't seen much discussion of the warrant in assuming that P(R/G)>0.5, where G stands for "God" or "gods". Plantinga seems to think it's a warranted assumption, but I'm not sure why I should accept this, because there are a lot of gods I can think of that aren't concerned with providing humans with reliable cognitive faculties. I think a defender of naturalism should focus on this a bit more, instead of always defending her warrant in assuming P(R/N&E)>0.5.

I agree with you. Naturalism is not specifically opposed to Christianity, or whatever God Plantinga has in mind. Naturalism excludes the existence of all gods, including those gods for which P (R/G)<0.5. So, G would actually be a collective hypothesis (more correct, a conjunction of hypotheses). The supernaturalist hypothesis is satisfied by any god, without any preference for some "reliabilistic" God. And given these hypotheses it is not at all warranted that P(R/G) >0.5.

Secondly, if our faculties are indeed unreliable (this is a matter of fact), this would count as an evidence against G, since under Plantinga's G we would expect our faculties to be reliable.

SwoleMan · 06-30-2007, 05:41 AM

Quote:

Originally Posted by Bobinius

I agree with you. Naturalism is not specifically opposed to Christianity, or whatever God Plantinga has in mind. Naturalism excludes the existence of all gods, including those gods for which P (R/G)<0.5. So, G would actually be a collective hypothesis (more correct, a conjunction of hypotheses). The supernaturalist hypothesis is satisfied by any god, without any preference for some "reliabilistic" God. And given these hypotheses it is not at all warranted that P(R/G) >0.5.

Exactly, it's not naturalism vs. Christianity, but naturalism vs. supernaturalism.

Quote:

Originally Posted by Bobinius

Secondly, if our faculties are indeed unreliable (this is a matter of fact), this would count as an evidence against G, since under Plantinga's G we would expect our faculties to be reliable.

Yes, I also think this is fact speaking against Plantinga's G. He tries to explain it away by sin (which seems to be kind of a universal solution to things we wouldn't expect under the G hypothesis), but isn't very successful IMHO.

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06-21-2007, 09:29 PM	#11
show_no_mercy Veteran Member Join Date: Jul 2004 Location: Dancing Posts: 9,940	Plantinga's argument seems like a very sophisticated version of Argumentum ad logicam, where just because someone has a false premise means that their conclusion must be false. That is, in fact, false. I can have all false premises, go through them via valid deductive inference, and arrive at a true conclusion. Just because the premises are false doesn't mean the conclusion is false.

06-22-2007, 04:47 AM	#13
post tenebras lux Veteran Member Join Date: Aug 2004 Location: Republic and Canton of Geneva Posts: 5,756	Is that what Plantinga thinks? I didn't think he was in the "T.Rex ate coconuts" box. If you weren't joking, that is.

06-22-2007, 05:57 AM	#15
SwoleMan Veteran Member Join Date: Mar 2004 Location: Sweden Posts: 1,190	I've read what I think are good refutations of the argument that the assumption that, as Plantinga puts it, P(R/N&E)>0.5 isn't warranted. But I haven't seen much discussion of the warrant in assuming that P(R/G)>0.5, where G stands for "God" or "gods". Plantinga seems to think it's a warranted assumption, but I'm not sure why I should accept this, because there are a lot of gods I can think of that aren't concerned with providing humans with reliable cognitive faculties. I think a defender of naturalism should focus on this a bit more, instead of always defending her warrant in assuming P(R/N&E)>0.5.

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