Thursday, March 19, 2009

First Draft of Plantinga Paper (part 1)

see new draft published 23rd March

18 comments:

wombat said...

A couple of quick comments.

1) Adaptive behavior - do you just mean behavior which enhances individual survival? The examples given both yours and Plantinga's don't seem to adapt to anything at all.

2) the notation "R on N&E + C" seems like either mathematicians slang or just loose. I know that trotting out the full English phrase is going to be cumbersome but this just doesn't look right. What happens when you put numbers in and try to evaluate it?


3) Dennett calls attention to two types of animal behavior mechanisms situation -action machines and choice machines (based on work by Gary Drescher in "Made up Minds: A Constructivist Approach to Artificial Intelligence" apparently which I haven't got but see "Freedom Evolves", Dennett 2003). The first type of machine operates without the need for any "belief" at all. It covers conditioned responses like "face the light" of "smell tiger - run". The second type evaluates possible choices in terms of the agents goals and hence does what it does for a reason.

At first glance (and this may be an artifact of arguing against Plantinga's construction) there is a confusion between the two types of response. The reason part of it seems to be inserted arbitrarily into a simple situation-action setting. e.g for the tiger case the response could be generated by simply "wiring" the brains "tiger detector" straight to the part that make you run. Reasons are seemingly not needed in either case. Perhaps a more complex example is needed where the goal of the actor is an issue leading to a genuine choice.

4) Belief desire combinations do not exist in isolation (I think!) - your suicidal caveman for instance will have many possible exit routes as well as starvation (wild animals, falling off things, drowning etc). Similarly the action of eating may well satisfy or frustrate other desires - obviously hunger but maybe also the desire to remove other animals from the vicinity (by eating them) or needing to dispose of the stuff left over when you've takes the useful skin off. You mention this in the last section. I think it deserves more emphasis somehow.

im_michael_young said...

I'm probably missing something really stupid, but I've read and re-read and I don't see how the second supposed counter-inductive inference of B is actually a counter-inductive inference of the thing observed. How is:

If not forage and hunt, probably starve.

The counter-inductive inference of the observation that:

When not forage and hunt, usually starve.

? This is the inductive inference. Wouldn’t the counter-inductive inference be:
If not forage and hunt, probably not starve?

Related point-

"B concludes that if he hunts and gathers, he won’t get food to eat"

I can see that this is the counter-inductive inference of the observation that hunting and gathering usually leads to getting food to eat. But, given B's desire not to get food to eat, won't this lead B to hunt and gather (to his adaptive advantage)?

Eric said...

"At the heart of this larger argument lies what I call Plantinga’s belief-cum-desire argument. The belief-cum-desire argument is designed to show something more specific - that if the content of our beliefs does causally affect behaviour, and N&E, then the probability of (R) cannot be high."

Stephen, I'm not sure I'd agree that Plantinga's 'belief-cum-desire' argument is at the heart of Plantinga's EAAN. Plantinga presents four ways to understand the relationship between beliefs and behavior given N&E, and claims that the most likely relationship is epiphenomenalism. In fact, he argues that even if the conditional probability of R/N&E + C (where C is understood as "the content of beliefs causally affects behaviour" *adaptively*, not simply that our beliefs causally affect our behavior) is high, the conditional probability of R/N&E is still low (i.e. less than .5) given the other possible relationships between belief and behavior -- (i) epiphenomenalism, (ii) semantic epiphenomenalism (or, in other places, by way of their electro chemical properties, but not their semantic content), (iii) causal but maladaptive, (iv)causal and adaptive. The first three possible belief/behavior relationships have more obviously low probabilities assigned to them than (iv), which would of course adversely affect the overall probability that our cognitive faculties are reliable given N&E.
Also, note that your (c) conflates the last two categories, which would affect the conditional probability by reducing Plantinga's P(R/N&E) = (P(R/N&E&P1) x P(P1/N&E)) + (P(R/N&E&P2) x P(P2/N&E)) + (P(R/N&E&P3) x
P(P3/N&E)) + (P(R/N&E&P4) x P(P4/N&E))

to

P(R/N&E) = (P(R/N&E&P1) x P(P1/N&E)) + (P(R/N&E&P2) x P(P2/N&E)) + (P(R/N&E&P3) x
P(P3/N&E)).

faithlessgod said...

Good to see an explication of what I have always argued for. Evolution does provide reliable means of inference - adaptive reliability but not infallible means of intentional action via intention formation via belief-desire combinations.

Still one can look and possibly find some false beliefs that have adaptive value - this is E. O. Wilson's practical versus true belief argument over religion comes to mind. Now whilst I disagree with it, it is not something that Platinga would bring out being contrary to his intention and that might be another argument against Platinga, religion evolves belief-desire combination that are false yet..ahem.. religiously adaptive ;-)

I agree with another poster that your counter-inductive second example is not clear. Do you need it? Since you already use a FAC why not contrast this with a FDA contrast and leave it at that?

As for the four categories of explanation noted by the last commentor surely using Baysian classification of categories would make our category a posteriori the most likely correct?

See you tomorrow at Conway Hall, thinking of live blogging again is anyone else interested in joining me on that?

Martin

Geert Arys said...

English is not my native. But still, I had to read:
B observes that other hominids that forage and hunt get food to eat, and those that don’t starve. B concludes that if he hunts and gathers, he won’t get food to eat, and if he doesn’t, he’ll starve.
several times before I get the point.

B observes that other hominids that forage and hunt get food to eat, and those that don't starve.
He concludes (counter-inductively) that he won't get any food.
From this belief he won't get any food he concludes (counter-inductively) that he'll live.

(and B does not want to live)

Even previous example was a bit unclear:
B observes that whenever other hominids eat, they usually continue to live, and when they stop eating, they die. He concludes that if he eats, he’ll probably die, and if he stops eating, he’ll continue to live.

I had to read that a few times.
B observes that whenever other hominids eat, they usually continue to live, and when they stop eating, they die. He concludes (counter-inductively) that if he eats, he’ll probably die, and if he stops eating, he’ll continue to live.

The insertion of the word draws the attention to the fact that this sentence varies with the previous one.

Stephen Law said...

Thanks for comments - rejigging accordingly. made a slip when setting out counter induction example.

Geert Arys said...

Something else, about:
So far, it seems that Plantinga is correct: given evolution equips A and B with the right desires, the behaviour produced by the two belief-forming mechanisms is equally adaptive.

Is this (and similar) correctly phrased?
I'd rather say:
"So far, it seems that Plantinga is correct: A and B are equipped [genetically] with the right desires, the behaviour produced by the two belief-forming mechanisms is equally adaptive, and thus equally successful in an environment of natural selection."

Because in the first wording, It immidiately came to my mind that "ah, A and B are equiped by 'evolution', so it's already proven that they are equally successful".

faithlessgod said...

woops mean D.S. not E.O. Wilson

Geert Arys said...

Stephen,

I see an obvious (albeit intuitively wrong, I'll admit) critique:

"Stephen only counters 2 possible behaviours at a time: inductive and counter-inductive. Platinga's argument, however, considers a myriad of other possibilities"

So, you're making a false binary choice. If you're only presented 2 possibilities, the 'right one' is unlikely to have an inscrutable probability. The 'inscrutableness' results from the sheer mass of possibilities.

I'd counter that by saying: the nature of evolution is adding to an existing working system, not choosing between a myriad of possibilities appearing out of thin air. (How you write that formally, beats me)

How do you counter this argument (false binary choice)?

The Barefoot Bum said...

There's a deeper problem with Plantinga's analysis. He takes for granted that we can talk about a being's beliefs independently of his behavior. But we cannot actually do so. In practice, we must infer the content of his beliefs from his behavior.

If we observe some hypothetical alien consistently running away from and hiding from a tiger, we can infer only that he believes the tiger to be dangerous.

Plantinga is just reworking the old underdetermination argument against naive empiricism. But this argument has already been addressed, and the same refutation applies to this argument: a theory has no content other than its predictions: Two "different" theories that always make all the same predictions are really the same theory. In just the same sense, a belief doesn't "have" causal properties, a belief is a set of causal properties, and has no content other than those causal properties.

Plantinga asserts that different kinds of neural structures can have the same adaptive efficacy. Granted, but so what? Plantinga then goes on to arbitrarily assign one (or a small subset) of those neural structures the property of being "true" and others the property of being "false". But on what principled basis can Plantinga make this distinction? In his argument, you can clearly see his appeal directly to our intuition in making this distinction, without a principled basis.

Consider a suite of some "differing" neural structures. Each individual structure in this suite can always, sometimes, rarely or never produce adaptive behavior. We are simply not entitled to ascribe any properties to these structures except those related to or inferred from their causal effect on behavior.

Plantinga also tries to fool us by describing beliefs in terms of their causal effects such that the belief is adaptive only within a restricted set of circumstances, and then implying the belief is always adaptive.

I go into this line of reasoning in more detail in my essay: Reliable belief-producing faculties.

Geert Arys said...

A thought:

Now, if you start with only non-sentient reactions (no beliefs at all), the first few beliefs a species gains are (generally) more useful if they are true. For instance, the belief that you need to stay away from tigers is given no other beliefs more useful than not having it.

One can easily argue (using Stephen's examples) that gaining one single true belief is (generally) more useful than gaining one single false belief if a species already has (a majority of) true beliefs.

The nature of evolution is that a species (generally) adds more complexity as long as the new features are useful to survival.

It follows that there is a good chance that a species with a complex system of beliefs will hold a majority of (generally) true beliefs [because on a one-by-one evaluation, true beliefs are more useful AND evolution often results in slowly growing complexity].

I have to say "generally", because there are false beliefs too. Proof are many false religions there are in the world (read: all religions you happen not to believe in).

Andrew Louis said...

The problem I’m seeing here is the unnecessary split between beliefs and behavior (habits of action), and it seems that BB’s last comment is one that certainly recognizes this and effectively recombines the two. Beliefs ARE habits of action.

I believe BB is exactly right when he says:
“He [Platinga] takes for granted that we can talk about a being's beliefs independently of his behavior. But we cannot actually do so.”

The “true” and “false” being thrown around as they are seems to suggest that the way truth is being looked at is relative to the idea that beliefs (couched in a language practice) are representations, and thus in this way we create a split between accuracy of representation relative to the actions involved and effectively say, “H1’s belief represents falsely as his action contradicts his desire.”. But this assumes, as BB already pointed out, that we can have some means of privileged access to these beliefs separate from an individual’s actions.

However if we look at beliefs AS habits of actions, we begin to see that “two different beliefs that lead to the same prediction are really the same”. In another way, a belief that we would assume to represent X, but always produces behavior Y as apposed to X, may be simply due to our failed interpretation of what the person means, not that they’re “representations” are incorrect. Since again, beliefs are habits of actions, we cannot say this person is holding a false belief with respect to his action, only that, perhaps he speaks in a way different or opposite from the rest of us – in which case we have to go about the task of finding a better way to interpret him that’s consistent with his actions and not what we infer from his speech even given that it seems to resemble our own.

The Barefoot Bum said...

e have to go about the task of finding a better way to interpret him that’s consistent with his actions and not what we infer from his speech even given that it seems to resemble our own.

Keep in mind that speech is an action, and a speech action which directly references a belief (e.g. "I believe that evolution is true") is not necessarily veridical: the speaker may be mistaken, confused or lying.

This aspect of the issue is most noticeable when we intentionally exclude our unconscious biases interpreting people who speak our own native language and engage in a Quinean "radical translation" project. We then are in the same boat regarding language as Plantinga is regarding "belief": We can assign meaning to the new language only on the basis of observing the correspondence of language with actions.

Although Quine casts doubt on whether we can make inferences about language with deductive certainty, we are most definitely not entitled to decide that "gavagai" means "thunderstorm" or "eating", at least not without making a mockery of Occam's Razor.

Stephen Law said...

BB is right I think that P is vulnerable to another line of attack as well - to just deny that most of our beliefs could be false. Both Hilary Putnam and Donald Davidson have argued that it is impossible for most of our beliefs to be false (Davidson's arg being quite like BB's I think).

Eric is right in part about the scope of the argument - I will make an adjustment.

David B. Ellis said...


Both Hilary Putnam and Donald Davidson have argued that it is impossible for most of our beliefs to be false (Davidson's arg being quite like BB's I think).


Where? I'd be interested in reading what they wrote on the topic.

im_michael_young said...

A slight tangent: in answering Plantinga generally, the paper and some of the comments here are also about evolutionary theory more generally, and particularly whether the theory has the power to explain the origins of reliable belief-forming, or mostly true believing. An answer to Plantinga will also be a "yes" to the question of whether the theory can explain these phenomena.

I find that interesting because it suggests that evolution in general can be a tool for understanding the origin of the stuff of rationality. (For lack of a better phrase; be charitable, it's a working concept.) In general, I guess that's not a surprise, but to work out the details seems interesting, even exciting. So, anyway, I'm rooting for the success of the Prof. Law's paper for multiple reasons.

And in this vein, maybe the CFI could sponsor an interdisciplinary conference on the evolution of the stuff of rationality? (Might include sessions on the origins of morality, the origins of reliable believing, the origins of a sense of free will (or free will itself).) A random, half-developed thought...

wombat said...

Stephen,

Plantinga makes the distinction between beliefs and desires, your line of attack hints that there is a further separation which can (and should) be made, which is to say the thinking tools used to decide on the best course of action at any juncture. In your two examples showing FAC and counter induction this begins to come out. Surely we must consider the evolution of these methods in themselves. That is to say what is the probability that an organism will evolve a generalized FAC module or a counter-induction module?
Why should we believe that evolution will encourage a separate general purpose reasoning facility rather than acting on a case by case basis? (1) economy - there will be a cost associated with the additional complexity of millions of belief/desire pairings either in material terms (memory space) or perhaps in time taken to react. (ii) generality - this sort of mental architecture will at least have something to say when confronted with a new situation, and there is a chance that the decision it makes will be useful whereas simply having an "Hmm this is new.." sort of moment will be a poor response to predators.

Eric Sotnak said...

Following up on comments by wombat...
In addition, on Naturalism. belief-having creatures evolved from creatures that did not have beliefs, but which, nevertheless, had internal states which performed the same functions as beliefs. A creature follows a chemical scent trail and successfully locates a mate. If such states did not track truth, they would not be adaptive. Now consider that on Naturalism, belief systems evolved from these non-belief precursor systems. It must be possible to give some plausible evolutionary account whereby the former is converted from the latter. It seems to me that Plantinga's alternate hypotheses do a poor job of fitting into this evolutionary scheme. Details matter.