h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Hi psi

Somewhat ironically my acquiring an information on human stem cells*** (my area of expertise being mucking about with unicellular beasties ) to take over a project for an ill colleague I now have more free time to concentrate on Plantinga

A bit out of touch as to where we are precisely but I think my last substantive reply was my #556 to your #547 so I'll start from there. I notice that The Bull and the thread is still accessible though no longer postable. I'm not clear how long this situation will persist. Do you?
If it is short term then I might have to spend some time copying your posts to Notepad or somesuch.

Afaik, h2g2, does /not/ support BBC-type quote boxes but does seem to support some elements of HTML so an alternative may be available. In the meantime perhaps we might surround quotes from our respective posts with //......//

I'll have to spend some time catching up with your posts before essaying a reply.

***In my reading came across a paper which showed that purely human (though perhaps some inherited from earlier hominids) higher cortical structures develop from different stem cells. Not mentioned in the paper but it seems reasonable to assume that these evolved at different times.

Must away for now

bs

Hi Bx4,

My understanding is that The Bull threads will remain accessible for the foreseeable future.

Maybe I'll experiment to see what we can do about quotes but will follow your suggestion in the meantime.

ttfn

Hi psi

I read somewhere that h2g2 supports frames so it may support blockquotes. I'll have a look when I get up to speed on

HTML again.

I am in the process of drafting a reply to your 564 but it will take a few days

I look forward to it.

ttfn

Hi psi

My 'adamantine resolve' /not/ to get involved in either of the new Mustardland board collapsed because of getting involved in yet another Scottish Independence and then got into a spat with the moderators.

Anyhow, I am now resolved -honest- to concentrate on Plantinga for a bit.. Slight difficulty in working out hw to describe my ultra-minimalist monism but i'll get there
bs

Hi psi

I had begun to reply to reply to your earlier posts but found myself in some difficulty in part because I had been absent for so long that I was no longer sure the precise intention of the point I had been making tp which you were re.
because our conversation re Plantinga had become somewhat involuted .

I also recalled that when I introduced Plantinga (mea culpa, mea maxima culpa) into the thread in the 'other place' I didso by saying that while I generally disagreed with Plantinga I was broadly in agreement with text (a).

Therefore, I thought it might be worthwhile to opt for a clarification of this, that is to distinguish between those elements of Plantinga's stance that may be consistent with text (a) but are not essential to it, before dealing with your posts.

bs

Yes that might be a good place to resume, especially if you can paste a copy of text a) here to save me digging it out of the thread.

Hi psi

Doing quite well. Ten paras so far and am about to start on mind brain dualism.
bs

Hi psi

Doing quite well. Ten paras so far and am about to start on mind brain dualism.

Text (a) already included as is Patricia Churchland's slightly different view of the subject as text (c)
bs

Looking forward to it.

ttfn

Hi psi

Finished with 'mind-brain dualism' bit now moving onto the 'probability hypothesis' then it's a wrap.

hi psi

Meant 'thesis' not 'hypothesis'

Progress a bit slower than anticipated. In part because of diversions elsewhere. In part because I had to do more research on conditional probability than anticipated to confirm, I hope,my intuition that the mathematical basis of the 'probability thesis' is inconsistent and incoherent.

That only leaves P's assertion that the value of P(R|N&E) is either low or inscrutable to deal with.

hi psi
Finally

Before replying to your #564. I think it might be useful to clarify my position with regard to text (a) and Plantinga's position in general:

(a) 'What our minds are for (if anything) is not the production of true beliefs, but the production of adaptive behavior: that our species has survived and evolved at most guarantees that our behavior is adaptive; it does not guarantee or even make it likely that our belief-producing processes are for the most part reliable, or that our beliefs are for the most part true. That is because our behavior could perfectly well be adaptive, but our beliefs false as often as true.' (Science and Religion; SEP)

In reading (a) we need to take into account that Plantinga, as a Christian polemicist, is in fact /attacking/ the position outlined as he makes clear with:

(b)'If natural selection were guided and orchestrated by the God of theism, for example, the worry would disappear; God would presumably use the whole process to create creatures of the sort he wanted, creatures in his own image, creatures with reliable cognitive faculties. So it is unguided evolution, and metaphysical beliefs that entail unguided evolution, that prompt this worry about the reliability of our cognitive faculties.'


While I have indicated that I agree with (a) I only do so in the same sense that I agree with this from Patricia Churchland (quoted in Plantinga's 'Warrant and Proper Function'):

(c) 'Boiled down to essentials, a nervous system enables the organism to succeed in the four F’s: feeding, fleeing, fighting and reproducing. The principle chore of nervous systemsis to get the body parts where they should be in order that the organism may survive... Improvements in sensorimotor control confer an evolutionary advantage: a fancier style of representing is advantageous so long as it is geared to the organism’s way of life and enhances the organism’s chances of survival. Truth, whatever that is, definitely takes the hindmost'.

So, for me:

(d) The common element is that evolution selects for adaptive behaviour that promotes reproductive fitness and if beliefs are implicated in the adaptive behaviour then in evolutionary terms it is their contribution, in a given context, to the promotion of reproductive fitness rather than their truth value that is important.

To say this is neither to say that all adaptive behaviours have beliefs implicated in their causal chains nor that all beliefs are implicated in causal chains leading to adaptive behaviour.

To restate the obvious I am of course using belief in the narrow sense of the propositional of attitude and, because I cannot realistically extend a theory of mind to other species, I am only talking about human adaptive behaviour.

Now, you have made the point that text (a) is 'consistent' with Plantinga's philosophico-psychological stance whether based on his semantic epiphenomenalism (SE) or non reductive reductive materialism (NRM) which seems to have replaced which seems to have replaced it in his ant-thesis, P(B | N&E&NRM).

However, I would make a distinction between 'consistent with' and 'required by'. I don't think my interpretation of text (a) depends on on a philosophico-psychological model that assumes mind-brain dualism. Plantiga's attempt to present his anti-thetical thesis in terms of a distinction between the syntactic (neurophyiological) properties of a belief and its semantic (mental) properties is not required by text (a) though it may be consistent with it.

It is not precisely clear what Plantinga, in his 2010 SEP article, means by non-reductive materialism though it would seem to be something akin to supervenience physicalism. No matter, my distinction between 'consistent with' and 'required by' would still apply.

[This next bit might seem a bit of a diversion but it underpins my current thinking of the relevance or otherwise of the 'philosophy of mind]' to my text (d).]

I am not wholly persuaded that any psychologico-philosophico stance as to the way the brain or 'mind' functions is of much relevance. Science differs fundamentally from philosopy in that prunes failed research programmes, theories and paradigms whereas in philosophy they mostly just accumulate though they may go out of fashion for some time.

Part of the problem is that philosophers, with some notable exceptions, really don't get the implications of ongoing neuroscientific research. So while they graft a vocabularly of 'neurophysiological properties' and suchlike onto their particular philosophy of mind there is generally no fundamental change in these philosophies which retain elements of folk psychology and archaic philosophical models of the mind.

My position might seem close to eliminative materialism but this is only the case insofar as I accept the radical claim that our ordinary, common-sense understanding and archaic philosopical models of the mind are deeply wrong but not that some or all of the mental states posited by common-sense do not actually exist (modified from 'Eliminative Materialism', SEP)

I mentioned earlier that I came across some studies which showed that different parts of the human prefrontal cortex arose from different stem cells and it seems unlikely that these evolved simultaneously. So it it seems quite reasonable that one part of the cortex should have evolved to observe other brain states. In effect, the brain structure responsible is a /monitoring instrument/ of other cortical states.

If we consider other monitoring instruments EEG,fMRI and fIR which detect different, respectively electrical, magnetic and infrared, phenomena produced by the same inaccessible ding a sich. My view is that the phenomenon of a 'mental event' 'perceived' by an internal instrument is no different from these.

Since it is by no means clear how you would show that any particular current psychologico-philosopical mind-brain model is to be preferred over any of its contemporaries , it does not seem to b any point in assuming that text (a) as dependent on that particular model.

[Since writing the above I came across a letter by Mary Midgely in New Scientist (23/03/2013) in which she says of mind-body dualisms:

{T}hey are just a continuation of parts of the argument by 17th-century philosopher Rene Descartes for a separate substantial soul..{in his} dualist world of separate mind and body a place we no longer need to visit.'

So it would seem that while text (a) does not require Plantinga's dualism his Christianity does.]

So coming to Plantinga's 'Probabability Thesis' , P(R|N&E) there seems no merit in presenting as either P(R!N&E&SE) or P(R|N&E&NRM) as Plantinga does.

As I have said on the now defunct mustarland thread I think the P(R|N&E) is problematic because:

(1) There seems no obvious way of showing that statements like 'that reality is exhausted by nature, containing nothing ‘supernatural’ ['Naturalism', SEP] are truth-apt let alone true.

(2) The notion that the theory of [unguided] evolution is true seems problematic given that the Modern Evolutionary Synthesis is still very much a 'work-in-progress', particularly as far as its genetics component is concerned. So whle the MES contains statements that have different truth values, true, false or unknown, it seems meaningless to assert that the MES is true or false.

(3) If the individual terms of the logical conjunction N&E are problematic with respect to their truth values then the truth value of the conjunction is thereby also problematic

(4) Plantinga's 'Let R be the proposition that our cognitive faculties are reliable(P1), N the proposition that naturalism is true(P2) and E the proposition that we and our cognitive faculties have come to be by way of the processes to which contemporary evolutionary theory points usP3)....' (Religion and Science', SEP) faces the problem that if neither N nor E is truth apt and as a consequence neither is N&E then it would inevitably follows that N&E->R is also not truth apt.

[As an aside note that in this article that 'R is the proposition that our faculties are reliable'(P1) rather than 'mostly reliable'. I don't think it serves much purpose to reinterpret 'reliable' as meaning 'mostly reliable' since all we can reliably say is that Plantinga is inconsistent with respect to (P1). Howeve I don't think that /whichever/ interpretation one adopts it materially affects my argument.]

Given that Plantinga's argument is unsound:

'A deductive argument is sound if and only if it is both valid, and all of its premises are actually true. Otherwise, a deductive argument is unsound.' ( Validity and Soundess', IEP)

in propositional logic it is perhaps unsurprising that at the end of the last quote that Plantinga comes up with the legerdemain '...what is the conditional probability of R on N&E? I.e., what is P(R | N&E)?' which attempts to move the argument from one in propositional logic to one in conditional probability. As far as I can see nowhere does he provide a justification for this shift.

The question is whether his 'probability thesis' is consistent with conditional probability.My argument is that it is not. Firstly because conditional probability as conventionally understood is a probability of /events/:

'The conditional probability of an event B is the probability that the event will occur given the knowledge that an event A has already occurred. This probability is written P(B|A), notation for the probability of B given A. In the case where events A and B are independent (where event A has no effect on the probability of event B), the conditional probability of event B given event A is simply the probability of event B, that is P(B).

If events A and B are not independent, then the probability of the intersection of A and B (the probability that both events occur) is defined by P(A and B) = P(A)P(B|A). '
http://www.stat.yale.edu/Courses/1997-98/101/condprob.htm

The point I have made earlier is that none of R, N and E events and so there is no reason to assume that the use of conditional probability is warranted and so, in Plantinga's terms this is a /defeater/ for P(R|N&E).

However, assuming, arguendo, that it is not then his 'probability thesis' relies on two /or/ three dependent 'events' dependng on whether the conjunction N&E is considered as a logical conjunction or a conditional probability intersection.

'For two dependent events we have:

P(E1 and E2) = P(E1) × P(E2 | E1) {1}

For three dependent events E1, E2, E3, we have:

P(E1 and E2 and E3) = P(E1) × P(E2 | E1) × P(E3 | E1 and E2)' {2}

http://www.intmath.com/counting-probability/8-independent-dependent-events.php

or, in terms of Plantinga's 'events, N, E and R we have either

P(N&E and R) = P(N&E) x P(R|N&E) {1a}

P(N and E and R) = P(N) × P(E | N) × P(R | N and E) {2a}

I have not read Plantinga's 'Warrant and Proper Function' where presumably Plantinga's 'probability thesis originates but I have recently come across a paper by Sober and Fitelson, 'Plantinga’s Probability Arguments Against Evolutionary Naturalism' which reports that 'Plantinga uses Bayes’ Theorem, which says that this conditional probability is a function of three other quantities

Pr(E&N|R)=Pr(R|E&N)·Pr(E&N)/P(R)' (Note here '/' is used correctly as the symbol for division)

Note also that as of 1993 Plantinga argument was based on 'the probability of E&N given R', Pr(E&N|R, as distinct from his later 'the probability of R given N&E, P(R|N&E).

Nowhere. can I find any account that explains this shift but it certainly indicates an inconsistency as to the basis of the 'probability thesis'. In any case by 1994. in 'Naturalism Defeated', P(E&N/R) had been replaced by P(R|N&E) and by 2007, 'Naturalism vs. Evolution: A Religion/Science Conflict?', giving the supposed 'the calculus of probabilities (the theorem on total probability)':

P(R|N&E) = [P(R|N&E&C) x P(C|N&E)] + [P(R|N&E&-C) x P(-C|N&E)]{3}

However, the what the theorem of total probability actually says is:

'Given n mutually exclusive events A_1, ..., A_n whose probabilities sum to unity, then

P(B)=P(B|A_1)P(A_1)+...+P(B|A_n)P(A_n),

where B is an arbitrary event, and P(B|A_i) is the conditional probability of B assuming A_i. '

http://mathworld.wolfram.com/TotalProbabilityTheorem.html

So we now have R|N&E being treated as a /single/ 'event' rather than a plurality of either two or three dependent events.

In my view this is sufficient to show that the mathematical basis of Plantinga's supposed 'probability thesis' is sufficiently
flawed to make it both inconsistent and incoherent.

Assuming, arguendo, that Plantinga's 'probability thesis' is not conceptually flawed and turning to his assertion that P(R|N&E) is 'low or inscrutable'. Dealing with the latter claim first, my dictionary defines 'inscrutable' as 'incomprehensible' ('that which cannot be understood'), though, by a recourse to philosophical humptydumptyism, Plantinga has it meaning 'inscrutable--such that we simply cannot tell, except within very wide limits, what it is'.

It would seem obvious, contrary to Plantinga, that if P(R|N&E) 'cannot be understood' the the notion that it has /any/ meaning is incoherent.

As to low I had been going to look at the basis for this claim but I found this in Sober and Fitelson's ''Plantinga’s Probability Arguments Against Evolutionary Naturalism':

'Plantinga says (p.220, footnote 7) that his probabilities can beinterpreted either “epistemically” or “objectively,” but that he prefers the objective interpretation.However, Bayesians have never been able to make sense of the idea that prior probabilities have an objective basis.The siren song ofthe Principle of Indifference has tempted many to think that hypotheses can be assigned probabilities without the need of empirical evidence, but no consistent version of this principle has ever been articulated.The alternative to which Bayesians typically retreat is to construe probabilities as indicating an
agent’s subjective degree of belief.The problem with this approach is thatit deprives prior probabilities (and the posterior probabilities that depend on them) of probative force.

Now it is clear that in 'Naturalism vs. Evolution: A Religion/Science Conflict? (2007)' that Plantinga's is assigning a probability to P(R|N&E) without any empirical evidence and therefore that his 'probability thesis' lacks probative force.

My point is of course that my:

(d) The common element is that evolution selects for adaptive behaviour that promotes reproductive fitness and if beliefs are implicated in the adaptive behaviour then in evolutionary terms it is their contribution, in a given context, to the promotion of reproductive fitness rather than their truth value that is important.

does not require any philosophical assumptions about the merits or otherwise of competing ontologies, outmoded psychologico-philsophical models of the mind or 'probability thesis' based on problematic logic and mathematics.

Sorry that this has become much longer than originally anticipated. Also apologies for any typos, solecisms or semantic gobbledecook that has escaped my somewhat cursory proofreading.

Hi Bx4,

I think I understand your objections to the probability argument on the grounds of non truth apt statements, questionable evidence for priors and that the theoretical frame work used is about events. We could for the sake of argument assume that suitable truth apt statements could be devised and that events entailed by those statements could be substituted for the statements themselves in the probability calculations. Evidence for the priors might still be problematic but in any case I'm not minded to defend Plantinga here since I don't think his arguments work anyway.

I do still differ with you on text a) whereas I think your d) I could agree with, given a few caveats. I think Churchland's passage is ambiguous.

I think the problem with a) is the clause: 'That is because our behavior could perfectly well be adaptive, but our beliefs false as often as true.', which seems not only an invalid conclusion but prima facie implausible. So the main caveat I'd add to your d) would be that although the production of reproductive fitness is of course of primary importance, it seems likely that this might itself depend on having mostly true beliefs.

The last clause in c) 'Truth, whatever that is, definitely takes the hindmost' might be being used in the same sense as 'devil take the hindmost', in other words, if your belief 'these berries are not poisonous' is false, then your reproductive fitness might suffer, you are the 'hindmost'.

ttfn

Hi psi

Been having all sorts of problems with latest version of Firefox and could't display h2g2 so I hadn't seen that you had replied.
Currently on Bloatware Inc's offering.

I'll have a think about what you say and reply soon.

bs

hi psi

Bit busy in world at moment. Been noodling away at a reply. Will post tomorrow or Sunday at latest

bs

hi psi

I'm not wholly persuaded that we could develop truth-apt statements for the 'priors', ontological naturalism and 'unguided' evolution let alone constructing statements from them that would be propositions describing events.

Suppose, arguendo, we take a minimalist definition of ontological naturalism as 'Ontological naturalism is the philosophical stance that there are no supernatural entities or domains' then I can see no way how one could specify a set of /testable/ truth conditions that would make it true. In Plantinga's terms a defeater for ontological naturalism would be a set of /testable/ truth conditions for the statement 'Ontological supernaturalism is the philosophical stance that there are supernatural entities and/or domains'. However, afaik, proponents of either ontological stance have yet to provide any such testable truth conditions.


Moreover, I cannot see how one would modify the above statement on ontological naturalism into a statement that
describes an event. Moreover. as I have already suggested any /active/ theory such as the Modern Evolutionary Synthesis will contain some statements that are as yet unproven and could turn out to be false rather than true so I am not persuaded that one can reasonably describe an /active/ theory like the MES as true. So as with ontological naturalism (N) I do not see how one

could consider the MES (E) to be truth apt.

So if neither N nor E or both are not truth apt then it follows that the conjunction N&E cannot be truth apt.

Nor can I see how one would express the MES as a statement describing an event so it seems to me that the 'priors' cannot be modified to make the supposed 'conditional probability' P(R|N&E) a coherent mathematical expression.

As I said in my original post in the Bull thread I didn't generally find Plantinga's arguments convincing except for text (a) . However as I pointed out earlier Plantinga is /not/ making an argument in support of text (a) (and earlier variants thereof) but is arguing /against/ it so it seems to me legitimate to consider text (a) independently of the, imo, highly problematic 'probability thesis' intended to refute it.

So turning to your:

'I think the problem with a) is the clause: 'That is because our behavior could perfectly well be adaptive, but our beliefs false as often as true.', which seems not only an invalid conclusion but prima facie implausible.'

This sees to be a new objection to text (a) and one which seems to require that it be treated as a set of unambiguous formal, albeit non-symbolic, logical statements rather than as a set of ambiguous natural language ones which given the context in which it occurs it clearly is.

So I am not wholly persuaded that your approach is warranted but assuming, arguendo, that it is then I would agree that the proposition:

(i)In any instance of adaptive behaviour contributing to reproductive success then the probability of a belief that is causally implicated in that adaptive behavior being false is 0.5

is, I agree, itself, in most contexts likely to be false. However, I think your own claim that:

'So the main caveat I'd add to your d) would be that although the production of reproductive fitness is of course of primary importance, it seems likely that this might itself depend on having mostly true beliefs.'

is as much an invalid generalisation and is prima facie implausible as is Plantinga's. If we also apply the same formalism to your statement we would end with something like:

(ii)In any instance of adaptive behaviour contributing to reproductive success then the probability of a belief that is causally implicated in that adaptive behavior being false is significantly less than 0.5.

Imo, this suffers precisely the same problem as Plantinga's in that it is an over hasty generalisation. Both (i) and (ii) can only be considered truth-apt in a particular context.

To explain what I mean I want to return to a late iteration of my 'tiger' gedanken.

Assume, we have a dense jungle populated by tigers and kudus who are both adapted to that environment by being well camouflaged and that the sounds each species makes are indistinguishable. Assume further that humans have no option but to occasionally enter the jungle, say to collect an essential medicinal herb that only grows there.

The jungle is too dense to permit a visual identification of either a tiger or a kudu because of their camouflage so the only stimulus that results in an adaptive behaviour is the sound produced by a large unseen animal moving through the undergrowth that may, indistinguishably//, be produced either by a tiger or kudu.

Then surely it follows that the truth or falsity of the adaptive belief 'There is a tiger about/' is determined by the relative number of tigers and kudus in the environment; So that,for example, if:

(a)there were 9 tigers to every 1 kudu then the probability of the belief being true would be 0.9 (your contention)
(b)there was 1 tiger to every 1 kudu then the probability of the belief being true would be 0.5 (Plantinga's contention)
(c)there was 1 tiger to every 9 kudus then the probability of the belief being true would be 0.1

I would argue that (c) is more likely to be true given in fact that for large predators feeding on large prey, the number of such prey are usually found to be considerably greater than the number of predators.

I am not really clear why you think Churchland's text (d) //particularly// warrants the description of being 'ambiguous' since as I said early natural language statements of this type are often ambiguous which is why strictly they need to be mapped to statements in a formal language though this may difficult if the text involves metaphor or an element of humour.

I have some difficult with text (c) because unlike text (a) I do not know the context in which it is embedded. I have managed to find a reference to the paper:

Patricia Churchland, “Epistemology in an Age of Neuroscience,” Journal of Philosophy 84 (1987)

But I have not found it online. I did find another reference to the quotation wherein the text:

'a fancier style of representing [the world] is advantageous [**]so long as it is geared to the organism's way of life and enhances the organism's chances of survival[**]. Truth, whatever that is, definitely takes the hindmost.'

between the [**] is described as being italicised in the original.

I think we agreed on the Mustardland thread that Plantinga adopts a fairly conventional correspondence theory of truth which of course faces all the standard problems of relating the 'ding fur uns' relation to the 'ding an sich' so I think Churchland's view 'Truth, whatever that is' is preferable as it generalises the argument /irrespective/ of whatever theory of truth one adopts.

I'm not wholly persuaded by your attempt to equate her use of the hindmost with 'the devil take the hindmost' . Rather, hindmost simply means:

'Farthest to the rear; last'
(Collins English Dictionary)

So the more mundane interpretation would be that the truth is of less importance than that the belief is a component of an adaptive behaviour that 'enhances the organism's chances of survival'.

As for your narrative of the poisonous berries it would be the 'foremost' rather than the 'hindmost' who would be most likely to eat them first?
bs

Hi Bx4,

I do share your scepticism about the chances of formulating truth-apt statements that express ontological naturalism directly. I was thinking more of using as a substitute in the argument, something like 'evolution has been guided by an agent'. This removes the tricky notion of 'supernatural'. This would of course mean changing Plantinga's argument to use only those elements we could agree would be testable, but I'm fine with that since I'm not here to defend Plantinga's formulation. The event statement would be something like 'an agent guided the process of evolution at some time between t=0 and the present', the null hypothesis would be equivalent to a statement that there has been no guidance by an agent.

I am unclear why you think that the MES is not truth-apt just because it might contain false statements. If viewed as the logical conjunction of its statements then it is likely false as a whole but that would entail that it is truth-apt.

My objection to a) is that it is implausible on the face of it to suppose that an organism can proceed and survive in a complex and hazardous world unless it has mostly true beliefs. This does not require a) to be formal or logical so I'm unclear why you think it does.

So I think that your argument that the above is just as implausible as Plantinga's statement unpersuasive.

On your latest iteration of the tiger gedanken, I think this is defeated by characterizing the belief in the scenario to be 'that might be a tiger so I'd better run just in case'. In some situations we are prone to cognitive bias and false belief. We are particularly prone to this when it comes to risk assessment. You could therefore, without difficulty, point to instances where people are very likely to form false beliefs. For example with medical tests which have certain false positive and false negative probabilities. So really there is no need to invoke extreme circumstances involving running from tigers, the data are in, humans systematically get things wrong and we know some of the conditions which make this likely.

On the interpretation of Churchland I think it ambiguous because of the form of the phrase as a whole. I agree that we can interpret 'hindmost' according to the definition you have offered. But 'takes the hindmost'? That mirrors the popular phrase closely enough to wonder if this is coincidental. If she'd said 'is hindmost' that would be a different matter.

ttfn

hi psi

still busy

so reply later rather than sooner
bs