Friday 19 July 2013

Attacking the Evolutionary Argument Against Naturalism

My last post presented what I feel is the strongest form of the Evolutionary Argument Against Naturalism (EAAN) promoted by Alvin Plantinga.

Today I will attempt to refute it.

Rather than argue as some have that we can rely on our reason because of tools developed over centuries by a process of cultural evolution, I want to show that even the primitive faculties provided to us by evolution have given us abilities in this regard.

Unlike Plantinga, I certainly do not accept the premise that evolution and naturalism imply a low probability that we can reliably form beliefs.

Let's recall Plantiga's core premise (P1), regarding the probability (P) that we are reliable (R) given naturalism (N) and evolution E).
P1: P(R|E&N) is low - (there is only a low or negligible probability that we have the ability to reliably form true beliefs, given philosophical naturalism and evolution)
Plantinga's argument hinges on the observation that evolution only cares about adaptive behaviours, not whether the beliefs that are associated with those behaviours are true or false. This is true, however it doesn't help to establish P1 unless he can show that true beliefs are no more likely to be adaptive than false beliefs.

This is where I disagree with him. I think that true beliefs are far more likely to be adaptive, and this is why evolution would indeed select for the ability to form true beliefs.

Plantinga makes two major arguments to the contrary. Firstly (and most plausibly, in my view), he outlines the argument I spelled out yesterday. There are many possible motivations for any given adaptive behaviour, but only a tiny minority of these motivations will reflect a true, relevant belief about the world. Since evolution only cares about behaviour, the odds that a true motivation should be chosen seem slim. I will answer this later.

Firstly, I want to get the other major argument out of the way, because it has been brought to my attention that he tends to use it quite a lot when his other arguments are challenged. This latter argument seems to me to be quite obviously incorrect, so I will attempt to dispense with it as finally as I can.

I do not think I am being too unfair when I characterise this argument as the position that beliefs can have no effect on behaviour in a naturalistic world.

Of Course Beliefs Affect Behaviour

Of course beliefs affect behaviour! I find it extremely difficult to conceive of how someone could argue otherwise - after all, why would they argue that beliefs don't affect behaviour (this act of arguing being a behaviour in itself) if they were not motivated by their beliefs in that regard? If Plantinga seriously believes that naturalism does not allow for beliefs to affect behaviour, then he need not bother with EAAN. This should be his argument against naturalism.

The main motivation behind these views is the problem of reconciling the non-physical mental content of our minds with the physical structures comprising our brains. In the naturalistic world view, no non-physical event could ever have an effect on the material world, so it seems to be impossible to conceive of how it could be that something as insubstantial as a belief could set in motion the neural firings that lead to action and behaviour.

It should be said at this point that Plantinga himself need not be committed to this view, and indeed I believe he is not, since he is not a naturalist. He believes that the supernatural can indeed intervene in the physical world, so there's no problem as long as one accepts that the mind is not a purely natural phenomenon. Instead, he argues that a true naturalist should be committed to this position.

One solution to this problem is the suggestion that beliefs and other mental phenomena are not causative of behaviour but merely correlated with it. It could be that physical processes in the brain give rise to both beliefs and behaviours, but that the beliefs are a side effect and not causative of the behaviours. The sense that we experience mental phenomena and then act on those phenomena is an illusion. In reality, our behaviour is already determined by physical neural activity and the corresponding mental experience is just a story we tell ourselves. We are conscious automata. Beliefs, like free will, are an illusion.

Plantinga accepts this interpretation, as it sits well with his belief that the content of beliefs would have no effect on behaviour in a naturalistic world. Since beliefs are only the story we tell ourselves to explain our automatic actions, there is no reason to expect these beliefs to be true. As long as our behaviour is adaptive, our beliefs are irrelevant.

I feel this interpretation is valid to a point, but it's not the full story. I don't believe in free will (at least not in the old fashioned libertarian sense of the world), so in a sense everything we do really is determined by physical processes. It even seems valid to me to view mental phenomena as merely correlates of physical processes, but that's just one way of looking at it. 

(It's also fine in my view to see mental phenomena as actually causative. Neither interpretation is more correct than the other, it just determines on how one interprets concepts such as causation.)

But Plantinga takes it too far. He seems to think that since only the physical neural correlates of beliefs (e.g. the particular pattern of neural activity corresponding to that belief) matter from the point of view of evolution, therefore the content or meaning of that belief is irrelevant.

This is simply not true. What he seems to fail to appreciate is that the content of the belief is not independent of the particular physical pattern of neural activity, but that it is intimately bound to it. Different beliefs will correspond to different patterns of neural activity and vice versa. If evolution can select for adaptive physical brain states, then the corresponding mental phenomena are also being selected for implicitly. It really is not too much of a stretch to say that evolution is actually selecting for particular beliefs.

If you want more concrete examples of non-physical "epiphenomena" having a real impact on the physical world just look at the stock market, computer software, fashion trends. Examples abound.

The only question therefore is whether the beliefs evolution selects for are likely to be true or not.

The Adaptivity of Truth

My previous post outlined an argument that there are many more false beliefs that can lead to appropriate adaptive behaviours than true beliefs, and so we should not expect the probability that evolution selects for true beliefs to be high when it selects for the associated behaviours - far more likely that evolution will select a false belief that happens to lead to an adaptive behaviour. This argument may seem superficially convincing, but it is deeply flawed, as I will attempt to show.

When discussing the selection of behaviours, there are actually two quite distinct modes of behaviour selection to consider.

1) The direct selection of specific adaptive behaviours in response to specific stimuli
2) The indirect selection of adaptive behaviour by instead selecting for the ability to dynamically determine appropriate courses of action in response to experience and environmental conditions.

Many behaviours are due to the first kind of selection. We call these behaviours instinctive. All animals exhibit behaviours of this sort, and most exhibit only behaviours of this sort. They manifest as drives to engage in specific activities, but they are not motivated by beliefs about the world.

When a spider hunts down and kills a fly, it does not do so because it believes the fly will be tasty, much less because it believes it needs to eat to live. It does so because this behaviour has been hard-wired into it by evolution.

The same is true when you stand on a glass floor above a vertiginous drop. You may feel fear, but if I ask you whether you believe you will fall, you will deny it. Your discomfort comes from an instinctive response, not a belief. Even if you characterise this instinct as a non-propositional belief, as some do, it's entirely different from the kinds of beliefs Plantinga is talking about.

Plantinga would probably agree with this so far, but ask what this has to do with his argument. Well, I'm about to get to that.

When Plantinga discusses the possible beliefs that evolution might select for in order to produce a desired behaviour (e.g. running away from a tiger), he is making the mistake of treating these beliefs as if they are selected for directly, like instincts. Evolution requires a specific response to a specific stimulus. In order to get the appropriate result, beliefs are simply not required. This scenario is what instincts are for. You don't need a reason to run away from the tiger, you just need to run away from the tiger! You don't have to know that the tiger is going to cause you pain and death, you only need to feel fear and the impetus to get as far away from it as possible.

And yet we do have beliefs and the ability to reason. This allows us to surpass the crude stimulus/response behaviours allowed by instinct alone and so to behave far more intelligently (and so adaptively) than creatures such as spiders. Our ability to deliberate and choose our behaviour allows us to adapt to situations that could never have been foreseen by evolution.

The indirect mode of behaviour selection has come into play.

A hominid running away from a tiger quite likely does have true beliefs about the consequences of being caught. Humans and certain other animals form such beliefs every day, and their behaviour is motivated by the interplay of instinct with this dynamic and ongoing generation of beliefs. The correct question to ask is not, as Plantinga does, whether there are more true or false beliefs that could explain a particular behaviour, but rather to ask whether a reliable system for generating beliefs is more likely to lead to adaptive behaviours than an unreliable one.

Once the problem is explained in this way, it seems perfectly obvious to me that a reliable system would be more adaptive. The behaviours motivated by the beliefs generated by a completely unreliable system are likely to be effectively random, as there will be little correlation between reality and the generated beliefs. It's very unlikely that such a system would confer any evolutionary advantage whatsoever.

Yes, of course such a system could produce adaptive behaviours on occasion, such as in Plantinga's tongue-in-cheek example of the hominid that seeks to pet a fearsome tiger by running away from it, but such unlikely scenarios will certainly be outnumbered by examples of maladaptive behaviour. The same hominid is likely to run away from food, mates and other items of interest. Or suppose he is preoccupied and has no interest in petting tigers on this occasion, so he remains seated as the tiger approaches.

Only the beliefs generated by a reliable system will have any meaningful correlation with reality, and only beliefs which correlate with reality can consistently produce adaptive behaviour and so evolutionary fitness.

In conclusion, there is every reason to suppose that evolution has gifted us with some basic ability to form reliable beliefs in everyday scenarios. Given this basic foundation, we have over many generations built a great number of tools which allow us to perceive truths which were previously hidden from us. We are far wiser now than we were when we had only our evolutionary heritage to draw on, but all of our intellectual achievements to date have as their root the ability, selected for by naturalistic evolution, to form true beliefs reliably.

41 comments:

  1. Thinking of how we'd react regarding fire is better than a tiger. I think it was PZ Myers I was reading that used the example.

    Any well-functioning belief engine would form the correct belief regarding fire, if exposed to fire. It's hot and it's dangerous. Not because the belief is picked from the air on a whim, but because our belief engines are well honed. That thing gives you pain, that thing is dangerous. That thing only gives you pain at night or up close, then those are the conditions where it's dangerous. Infinite modifiers could accumulate to take the belief from the instinctive(vertiginous fear) to a more complex belief, as understanding develops.

    The set of 'possible' false adaptive beliefs is limited by what each person has experienced. In tribal times, that eliminates nearly an entire universe of knowledge. If their beliefs are formed from experience, then believing the tiger is in fact a dragon is impossible.

    Also, most false adaptive beliefs are one-time-use. If you think that petting a tiger is the best course of action, and you do it repeatedly, it's bound to come back to bite you.


    Is Platinga really so simple that he couldn't think of these points on his own? His argument must hinge on whether or not beliefs supervene on the brain. A necessary disconnect to shoehorn in a supernatural explanation.

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    1. I like your thinking, although I don't share your suspicion that Plantinga is simple. I think he has some sophisticated arguments to refute these points. I don't think these arguments succeed, but they appear to be convincing enough to convince him and others.

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    2. I must search a lot more to state this comfortably, but I can't resist to do it now: Plantinga was wholly conscious, step by step, of what he was doing. He found a breach in natural selection theory and used it (see my comment below) with the aim of reintroducing neo-thomism.

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    3. "I like your thinking, although I don't share your suspicion that Plantinga is simple. I think he has some sophisticated arguments to refute these points."

      You're right, that was arrogant of me. I read through most of the literature I could find, and the examples you used were also used in other texts. I'm not sure how you could defend the use of those examples in any probability set. In my experience, the defense would come at a right angle to my own understanding, and humble me. All the same, I'd greatly enjoy seeing his counter arguments.

      Instinctual behavior would be guided by evolution. Beliefs would be filtered by empirical processes. It does seem that between the two, there is a gap as Waldemar is saying. At some point, the focus shifts from 'survivability' to 'truthfulness'. Although I think the issue is that the transition between the two is merely obscured by complexity. Post a reply if you find further reading on this transition. I'll check back from time to time.

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    4. "At some point, the focus shifts from 'survivability' to 'truthfulness'"

      I don't see it as a focus shifting so much as the development of an alternative, complementary system of regulating behaviour. The old instincts are still there, but it turns out that the generation of true beliefs by an intelligent mind is an even greater boon to survivability.

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  2. I didn't finish yet the reading your text because I'm collating it with some of Plantingas's texts I found. However I guess it's possible to comment on isolated statements until I get the whole idea of the thing.

    "Plantinga's argument hinges on the observation that evolution only cares about adaptive behaviours, not whether the beliefs that are associated with those behaviours are true or false. This is true..."

    True? Why? In this point I must agree with Baron P, in which - let's say - decision-making is indissociable from whatever in every organism. It makes no sense to think in a science that considers the organism's side - its ability to react to the environment - and doesn't take this seriously into account. And that's what finally happens to biology: it conceives a physicochemical basis for the organisms' functions, including decision-making, but isn't able to link both sides.

    Now I start to see that this is a point that couldn't even be addressed by any philosophical argument trying to disproof Darwinism, since Darwinism simply doesn't consider it, at least in the way it deserves be dealt, say, as equally important as or still more important than the digestive functions. What could be done, if anything, is to ask biologists to address the matter as quick and as consistently possible.

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    1. I don't understand your problem with evolution here. I'm not clear on which two sides you are talking about.

      Decision-making is enabled by the brain. The brain can be thought of as an information processor analogous to the computer. It takes inputs from the senses, processes them, and delivers output to the muscles in order to take appropriate action. Decisions can be thought of as part of the information processing.

      The only mystery lies in the detail of how the processing is accomplished, and this is unsurprising because the human brain is the most complex object in the known universe. All the same, I don't see that there's any problem in principle with this high-level outline.

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    2. I agree entirely with your argument. But the problem is: Plantinga stresses and the evolutionists don't deny that, for instance, that "Natural selection favors advantageous behaviors, not directly the ability to form true beliefs" (as Massimo puts it), that meaning that the formation of true beliefs is not priority, a statement evolutionists can't verify otherwise. The problem here seems not to just conceive a meaningful way of giving true beliefs the priority, but to verify - experimentally, then - this conception. Am I wrong?

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    3. I'm not sure how you would verify this experimentally, but it seems obvious to me that true beliefs usually lead to advantageous behaviours, while false beliefs lead to mistakes.

      As long as we're doing philosophy (as Plantinga is), then the argument outlined in my post should be sufficient. I'm not making the claim that this interpretation has been empirically verified.

      However, experimental verification would seem to be impossible in principle as long as you are sympathetic to Plantinga's contention that wildly inaccurate beliefs could be what motivates all the sensible behaviours we see in our experimental subjects.

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  3. At the core of EAAN, whenever belief is true or false it doesn't matter as long as it lets creature to survive. There is only one "truth" (not necessary affecting behaviour adaptively) and there is very, very large group of false beliefs causing positive impact. They all are indistinguishable from evolutionary point of view.

    What about EAAN variation with musculoskeletal system? Similary, we have working musculoskeletal system (as we have working cognitive faculties), BUT our musculoskeletal system is only one out of many working musculoskeletal systems we can imagine, systems giving us adequate hands/tentacles/etc and good enough overall to be preferred by evolution. Even if we notice that we share some common skeletal pattern with our ancestors and other life forms form terapoda superclass, it doesn't help much - at best we are just in some subgroup, one of many. So, "logically" (*duh*) there is nearly infinite number of evolutionary scenarios leading to usable body (so we don't end up like dolphins), therefore probability of developing musculoskeletal system just like ours is low. And when we take into account scenarios leading to low manipulative skills it gets even lower. We should not expect creatures who have evolved naturalistically to have such. Must be God.

    In other words, it seems for me that showing some feature, attribute, thing is one out of many theoretically possible and indistinguishable for evolution shows exactly nothing or it is argument against evolution per se.

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    1. I don't think that line of argument quite appreciates Plantinga's point, though. He's not simply saying that out of all the ways we could have been it is unlikely that we could have ended up just so. Instead, he's saying that we have a very special ability and that this warrants an explanation.

      This is true. If you have some very special ability (such as the fine motor skills and musculoskeletal system needed to adeptly manipulate physical objects, or the intelligence to form true beliefs), then a naturalist evolutionist must suppose either that such a thing could have arisen by chance (which seems unlikely in these cases) or that it was selected for by evolution.

      The best counter-argument, in my view, is that the ability to form true beliefs, like the ability to manipulate objects, is indeed advantageous.

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    2. "I don't think that line of argument quite appreciates Plantinga's point, though. He's not simply saying that out of all the ways we could have been it is unlikely that we could have ended up just so. Instead, he's saying that we have a very special ability and that this warrants an explanation."

      And that's OK. The problem arises when you get to the probabilistic side of EAAN. To me, it's operating on sample space defined as set of all theoretically possible situations. Lets take option number 3 - "Beliefs tend to affect behaviour but are maladaptive." - and original Paul the Hominid & Tiger example. The only right behavior is to run, however, apart from that, innumerable actions will cause death. And thats only one predator, not entire savanna of them, not to mention that Paul has to eat (he runs from things he want approach...), drink and sleep. How "evolution" can check which actions are good or wrong? Off course, by trying it first. Lets assume Paul will face 10 critical situations in his early life. Lets say that in each we can cook up 99 fatal actions and one survivable. Approximately one Paul in 100 000 000 000 000 000 000 Pauls survives this death row. Entire population is going to extinct by one generation. (oh well, according to my math skills ;D ) I know there is no such thing in EAAN, but Plantinga's argument lacks crucial thing I would call a belief generating mechanism (that You are in fact introducing in counter-argument). Without this, it probabilistically works on space composed of unreal number of behaviors and beliefs, just as them would pop-up out of nowhere. Nature doesn't work that way, especially if you hard link belief and DNA for the sake of thought experiment. DNA slowly changes, not forms from zero in totally random way, thus overwhelming chunk of options is excluded and we don't really know what is left (tentacles are still an option?). Mutation and selection is a belief generating mechanism here. Example of death row is a nonsense of course, because it relies on unlimited randomness used as "belief generating mechanism".

      I think, one can't say that "probability is low", it is inscrutable (shows nothing), unless one come up with a model of belief generating mechanism. Then, one should look at the case again, firstly checking how model corresponds to reality. If it's acceptable and if one know one's model well enough, one can try to predict "what this could think" creating more reliable sample space and it's content.

      In even simpler words, one have to critically limit sets he is playing with. In Plantinga's approach - everything goes. If everything goes, look up for musculoskeletal example. The method is wrong.

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    3. I not 100% sure, but it seems that Plantinga's argument shoots its own foot (Brazilian expression), since it uses Bayesian technique, that is heavily based on belief (I mean, that incorporates it into probability calculations) and, obviously, takes just 'true belief' on account, to precisely show that true belief is not a reliable agent in survival matters. Am I wrong?

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    4. @Anonymous

      Sorry for the delayed response. I missed this comment somehow.

      I agree with your analysis!

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    5. @Waldemar

      Again, sorry for not responding sooner.

      I'm not sure I agree with your point. I see no obvious problem with using Bayesian methods to assess the probability of a belief being true.

      I apologise if I misunderstand you.

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  4. Hi Disagreeable,

    I think the case against Plantinga is even clearer when we see our beliefs as constituting a model of reality. It seems obvious that an organism with a more accurate model of reality will generally be more successful than an organism with a less accurate model of reality.

    These days Plantinga seems to rely much more on the first argument you mentioned: that on naturalism belief content must be an epiphenomenon, i.e. must have no effect on the physical world. In a radio interview I heard a couple of years ago he mentioned only this argument, and ignored the presenter when the latter brought up the "Paul the caveman" argument. I suspect he now realises how weak that argument is.

    "It even seems valid to me to view mental phenomena as merely correlates of physical processes, but that's just one way of looking at it."

    I like to use the philosophical term "supervene": mental states supervene on physical states. Our talk about mental states and our talk about physical states are just different ways that we model the same reality. Plantinga assumes that, if our actions are caused by neurophysiological states, they can't also be caused by beliefs. This is like saying that, because a flag's fluttering is caused by the movement of air molecules, it can't also be caused by the wind.

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    1. Agreed, Richard. I think your view is essentially the same as mine, I'm just a bit wordier!

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  5. Hey Disagreeable, theist (Catholic) here. :-) I know I'm a few months late, but I thought I'd chip in- hopefully you'll catch this, because I'd like to hear your thoughts!

    I think it'd be helpful to first clarify the context in which I'm guessing he developed the argument. The finest rendition of "the argument from reason" which I've found is in C.S. Lewis' Miracles, and I think Victor Reppert offers further thoughts in his book "The Argument From Reason." The briefest version: a universe which operates according to a naturalistic metaphysic cannot be relied upon to cause true mental beliefs in any organisms which may exist therein. In Plantinga's language, the likelihood of true beliefs is "low or inscrutable." (I may elaborate on the probability issue shortly.)

    I think Lewis' argument holds very good water; none of the naturalistic responses have been very convincing- Austin Cline (of about.com/atheism) doesn't seem to understand at all, Tattersall badly misunderstands Lewis' meaning of "naturalism" (as Barefoot's response captures fairly well), and Beversluis confuses the ontological existence of Modus Ponens (which Lewis agreed with) and Lewis' argument against the epistemological reliability of our *access* to valid thoughts in a naturalistic metaphysical framework.

    If Lewis' argument is good, and if naturalist philosophers wish to consider their own thoughts reliable, said philosophers must formulate a means by which organisms which exist in a naturalistic universe are likely to experience mental phenomena which accurately correspond to the world. One proposed "solution" is as follows: if an evolutionary biological process more highly favors the survival and propagation of organisms whose mental phenomena more accurately correspond to reality, organisms which are the result of long evolutionary processes *may* experience mental phenomena which reliably correspond to reality. If humans are the result of a long evolutionary process (which I don't think is an epistemically justifiable claim at this point in deliberation), humans may suppose that their mental phenomena are reliable.

    Plantinga's argument (which we're presently discussing) posits that an evolutionary process (as the term is understood in contemporary biology) doesn't *necessarily* favor the survival and propagation of organisms whose mental phenomena more closely correspond to reality. In fact, there's need be no correlation at all, because survival and propagation are physical, biological functions whose performance may be entirely independent of any mental phenomena which correspond to the occurrence of those physical functions. There could *incidentally* be a positive relationship between true mental phenomena and biological survival-and-propagation, but nothing about an evolutionary biological promises or even implies this.

    I think "evolutionary argument against naturalism" is a remarkably poor name; I don't think that it captures the gist of the argument well at all. He's not arguing that evolution makes naturalism less likely (as the name suggests); rather, he's arguing that evolution really doesn't impact the reliability of mental phenomena in a metaphysically naturalistic existence.

    (To be continued...)

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    1. You said: "If Plantinga seriously believes that naturalism does not allow for beliefs to affect behaviour, then he need not bother with EAAN. This should be his argument against naturalism."

      I think that's a perfectly good argument, and I'm interested in hearing your own thoughts (I believe you're a non-theistic naturalist?) about it. In a metaphysically naturalistic framework, an organism's mental phenomena may accurately reflect reality, but if the organism's grasp of reality can't affect its physical and biological functions, its true beliefs can't favor its survival and propagation.

      I think this argument might be better rendered like so: "in a metaphsyically naturalistic existence, any organisms' behavior and mental phenomena are the result of matter moving according to purely natural patterns. Neither 'behavior' nor 'mental phenomena' can be said to 'affect anything' in a way which isn't explicable purely in terms of matter-in-motion; the most accurate understanding of existence uses only the terminology of matter-in-motion. Any organisms/mental phenomena/behavior which result are entirely incidental. Consequently, there's no reason to believe that organisms' mental phenomena will reliably correspond to reality."

      In any event, the EAAN (as it's called) is a response to a feeble attempted response to "the argument from reason." The EAAN isn't an argument against naturalism *per se* so much as it's a defense of another argument against naturalism.

      If a biologically simple organism's accurate mental grasp of reality caused it greater success in survival/propagation, and if this kicked off a positive correspondence between mental grasp of reality and evolutionarily-advantageous behavior, one might reasonably conclude that organisms which are the result of a long evolutionary process can assess their mental phenomena to reliably represent reality. However, if a naturalistic metaphysical framework neither allows a causal relationship between mental and physical phenomena nor demonstrates a particular likelihood that evolution will increase organisms' grasps of reality through successive generations, the proposed "solution" fails on several counts.

      (To be continued...)

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    2. Hi Christian,

      Thanks for your comments. Feedback is always welcome.

      "
      If a biologically simple organism's accurate mental grasp of reality caused it greater success in survival/propagation, and if this kicked off a positive correspondence between mental grasp of reality and evolutionarily-advantageous behavior, one might reasonably conclude that organisms which are the result of a long evolutionary process can assess their mental phenomena to reliably represent reality."

      Yes, this would be my argument.

      "if a naturalistic metaphysical framework neither allows a causal relationship between mental and physical phenomena"

      I wouldn't agree with this. In a naturalistic worldview, mental phenomena supervene on physical phenomena and so there is a one-to-one mapping between particular beliefs and particular physical brain states. This mapping is not straightforward and will be idiosyncratic to each individual, but it exists.

      The idea is that those physical brain states which correspond to true beliefs are more likely to result in physical actions which are advantageous. So, perhaps non-physical mental phenomena don't directly cause physical phenomena, but they are isomorphic to physical brain states which do.

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    3. You say: "If evolution can select for adaptive physical brain states, then the corresponding mental phenomena are also being selected for implicitly. It really is not too much of a stretch to say that evolution is actually selecting for particular beliefs."

      If evolution physically-biologically "selects for" brain states which cause reality-matching mental phenomena, you'd be correct. No reason has been presented, though, that this should be believed. If mental phenomena are purely incidental to current brain states and don't affect the relevant physical-biological factors involved in "evolutionary selection," there's no reason that evolution would "select for" mental phenomena which better match reality. If mental phenomena are to affect "evolutionary selection," they must have some kind of causal relationship to the physical-biological factors which are involved in said selection. That kind of causal relationship is precisely what naturalism doesn't allow for, which is why naturalism isn't a reasonable metaphysical hypothesis.

      You say: When discussing the selection of behaviours, there are actually two quite distinct modes of behaviour selection to consider.

      1) The direct selection of specific adaptive behaviours in response to specific stimuli
      2) The indirect selection of adaptive behaviour by instead selecting for the ability to dynamically determine appropriate courses of action in response to experience and environmental conditions."

      Regarding your first point, I don't think behaviors are best described as "responsive" in a naturalistic metaphysical framework. All physical functions of the organism can be understood in terms of matter-in-naturalistic-motion, so why not just use that terminology?

      Regarding your second point, I think you're assuming an agency which doesn't exist in a naturalistic metaphysical framework. "Dynamically determining circumstantially appropriate courses of action," if it can really be spoken of in such a framework, requires two things: matter-in-naturalistic-motion must move in a specific way as to cause mental phenomena that perfectly recognize the physical situation and determine a particular course of action AND matter-in-naturalistic-motion must continue to move in a specific way in order to carry out said course of action. It's *possible* that both may occur, but it's extraordinarily unlikely in any given situation.

      Lewis' argument only concerned the part of first "horn" of that issue: naturalism can't be relied on to generate logical thoughts in organisms' mental experiences. Plantinga's defense concerns the second as well: naturalism can't be relied upon to cause advantageous action even if the mental phenomena is accurate. Your second point is valid regarding impact on "evolutionary selection," but it supposes factors at work which can't be reliably considered part of any organism's existence in a naturalistic metaphysical framework.

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    4. As to Plantinga's example involving Hominid Paul and the tiger, I find it confusing because I think his scenario contains an agency which isn't fundamentally possible in a naturalistic metaphysical framework, so I don't know why he includes it as part of an argument regarding naturalism. His point there would be better-expressed "even if individuals possess an accurate mental comprehension of reality and have some agency which allows deliberate decision-making, their reasoning for making evolutionarily-advantageous decisions may not always be sound." It's a sensible proposition, but the scenario presupposes a comprehension-of-reality which I would consider very rare in a naturalistic metaphysical framework and an agency which I don't think could fit at all.

      I'm not sure that I have any more comments regarding the initial post, but I've enjoyed this so far. Now on to your own response! :-)

      You say: "In a naturalistic worldview, mental phenomena supervene on physical phenomena and so there is a one-to-one mapping between particular beliefs and particular physical brain states."

      I'm not sure what exactly you mean by "supervene," but I think you mean it as a term of relationship between physical and mental states, and I agree with that. I just want to be sure that you're not thinking of any causal relationship which involves non-physical factors.

      You say: "The idea is that those physical brain states which correspond to true beliefs are more likely to result in physical actions which are advantageous."

      Why do you think such brain states are more likely to result in physical occurrences which benefit organisms' likelihood of survival and reproduction? I don't see any principled reason for why "accurate" brain states are more likely to cause advantageous physical occurrences than "inaccurate" brain states are. If (as in a naturalistic metaphysical framework) the only factors in play are physical, what difference does the "accuracy" of a brain state make? If there's no principled difference- and I don't think naturalism can provide any such difference- then reality-correspondent mental phenomena have nothing to do with physical "evolutionary fitness."

      You say: "So, perhaps non-physical mental phenomena don't directly cause physical phenomena, but they are isomorphic to physical brain states which do."

      I agree that this is the true constitution of a naturalistic existence which causes mental phenomena. I agree that mental phenomena equal brain states, but I don't agree that accurate mental phenomena equal brain states which will then cause evolutionarily-advantageous physical occurrences (in a naturalistic metaphysical framework).

      If you can't provide a reason why "accurate" brain states are *in principle* more likely than not to cause evolutionarily-advantageous physical occurrences, I think Plantinga's argument takes the day.

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    5. Hi Christian,

      I don't think you understand my view of how belief states can have physical effect. This is the only issue at hand in all of your comments, so if we can just iron this out all the problems should disappear.

      "Supervene" in this context essentially means that mental properties are "epiphenomena", meaning that they are emergent, high level phenomena which arise out of physical events. There is a direct mapping between mental phenomena and brain states, such that a belief that tigers are friendly will have one brain state and a belief that tigers are dangerous will have another.

      The physical brain state corresponding to the belief that tigers are dangerous will tend to cause a chain of physical cause and effect that would lead us to flee from a perceived tiger. The physical brain state corresponding to the belief that tigers are friendly is likely to have the opposite effect. This is so because the brain is a system shaped by evolution to "interpret" these brain states as having semantics which have implications for correct behaviour. The interpreted semantics are our beliefs.

      Perhaps this is easier to understand by looking at an analogy to a computer system, which is entirely naturalistic, well understood and uncontroversial.

      Computer systems can have beliefs, in that they hold within themselves a physical representation of propositions about the world. We might quibble over whether this is a true belief, but in a naturalistic worldview it is very closely analogous to a human belief.

      The physical representation (some pattern of electrons within a RAM chip, say) can have physical cause and effect, but it also has semantics, determined by the systems designer, such that the actions taken by the computer system are advantageous if the propositions implied by the semantics are correct and disadvantageous otherwise.

      So, if a particular cell in the RAM is positively charged, this might correspond to the proposition that a room is warm, prompting the system (by an unconscious chain of computations) to turn on the air conditioning. If the room is already cold, then this proposition is incorrect, and the system makes a mistake, wasting electricity and making the room far too cold.

      As such, beliefs can cause physical changes, and false beliefs can cause disadvantageous behaviours. As evolution selects for advantageous behaviours, it selects for the ability to form true beliefs as an indirect side effect.

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  6. Hi Disagreeable, I think we're coming closer to a understanding one another. Hopefully another few posts will clarify things!

    You say: "There is a direct mapping between mental phenomena and brain states, such that a belief that tigers are friendly will have one brain state and a belief that tigers are dangerous will have another."

    Let's stick with the aforementioned example involving Hominid Paul and a tiger. I agree that (in a naturalistic system) for Paul, one brain state equals "tiger friend!" and another equals "scary tiger!". Paul may occasionally experience one or the other phenomena. He may even (rarely) experience such phenomena in the presence of a tiger.

    What makes all the difference in biological "evolutionary selection" is the physical phenomena which Paul's body experiences when (in this example) he's near a tiger. I don't think that, in a naturalistic system, any tiger-involving mental phenomena is *in principle* more likely to lead to "running away!" physical phenomena than any other. I think that the physical phenomena which correspond to "scary tiger!" and the physical phenomena which correspond to "tiger friend" are equally likely, in principle, to lead to "running away!" physical phenomena. They're also equally likely, in principle, to lead to "pet the tiger!" physical phenomena.

    True beliefs can only *in principle* be evolutionarily advantageous (and thus "selected for") if their correspondent physical phenomena are *in principle* more likely lead to evolutionarily-advantageous physical phenomena than are the physical phenomena which correspond to false beliefs. I don't think that naturalism can supply any such principle.

    Why do you believe that, in a naturalistic setting, physical phenomena which correspond to true beliefs are more likely to lead to evolutionarily-advantageous physical phenomena than physical phenomena which correspond to false beliefs are? Unless you have a good reason (and I don't think there is one), the idea of evolution *in principle* "selecting for true beliefs" is invalid.

    I think this more clearly expresses my perspective, and I'm not sure that I understand how the computer system analogy ties in with the most pertinent issues at stake. Please let me know if there's something I've missed with it and draw your meaning to my attention if you think it'd be constructive. Thanks! :-)

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    1. I should clarify one of my expressions in my most recent comment. I said: "I don't think that, in a naturalistic system, any tiger-involving mental phenomena is *in principle* more likely to lead to "running away!" physical phenomena than any other." I think you probably understand the intended meaning, but I was inaccurate to frame things in terms of "mental phenomena leading to behavior" instead of "brain states which correspond to mental phenomena leading to behavior by way of matter-in-naturalistic motion." If everything in the naturalistic system is purely explicable in physical phenomena or by direct correspondence to physical phenomena, it's possible (and likely easier) to refer to all physical events in terms of physical phenomena instead of involving mental phenomena-related vocabulary.

      A more accurate rendering might read like so: "I don't think that, in a naturalistic system, any brain state which corresponds to tiger-involving mental phenomena is *in principle* more likely to lead to 'running away!' physical phenomena than any other brain state."

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    2. Hi Christian,

      All brain states have semantics, and they have semantics by virtue of how they intersect with other brain states. Brain states are not assigned semantics arbitrarily - the semantics arise from the behaviours the brain states cause including how they affect the state of the brain as a whole. As such, cause and effect is intimately bound to the semantics themselves.

      A brain state which has the semantics "tiger dangerous!!" is not usually consistent with those brain states which would cause Paul to approach the tiger (unless he has brain states with the semantics that he has a death wish, or is a thrill seeker etc).

      So semantics are not there as some meaningless side effect of brain activity. They *are* the meaning. Semantics must be consistent with behaviour or else all behaviour and brain states are meaningless.

      This is easier to understand with simple systems designed by humans, such as computers, which is why I think that you should consider the computer analogy carefully. For the computer, memory states which correspond to the idea that "the room is warm" really are more likely to lead to the computer turning on the air-conditioning, because that is how it is designed, just as we are designed by evolution to act in accordance with our beliefs.

      If the computer example isn't clear to you, then consider this. If you see a road sign with a speed limit of 50, physically this is just a piece of metal or plastic on a pole, pretty much identical to a sign indicating a speed limit of 70. And yet the non-physical semantics of the message on that sign will lead to different behaviour and different physical outcomes. Your idea that semantics has no relationship to physical cause and effect would seem to indicate that there can be no naturalistic explanation for how the sign affects the behaviour of road users.

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    3. Hi Disagreeable,

      You say: "All brain states have semantics, and they have semantics by virtue of how they intersect with other brain states."

      I'm not sure what exactly you mean by "semantics" here, and I find "semantics interacting by virtue" a bit confusing. I'll work with "semantics" defined as "the mental phenomena which are inherently correspondent to particular brain states." (The naturalistic metaphysical framework is still a given.) If my definition doesn't capture your meaning, please correct me.

      You say: "Brain states are not assigned semantics arbitrarily - the semantics arise from the behaviours the brain states cause including how they affect the state of the brain as a whole."

      If I understand, you're saying that (in a naturalistic framework) mental phenomena are non-arbitrary inasmuch as they're inherently tied to specific brain states. [Brain state x] equals [mental phenomena x], pick your variable. The mental phenomena experienced are directly and completely tied to the brain states which occur. I'd say that mental phenomena *are* arbitrary inasmuch as nature isn't obliged to cause any particular mental phenomena by way of particular brain state.

      You say: "As such, cause and effect is intimately bound to the semantics themselves."

      If I understand correctly, the naturalistic motion of brain matter is directly tied to the mental phenomena experienced. Said brain-matter-motion is the sole source of mental phenomena. If that's the case, I agree.

      You say: "A brain state which has the semantics "tiger dangerous!!" is not usually consistent with those brain states which would cause Paul to approach the tiger[.]"

      Here we part ways- I don't think this has been demonstrated at all. [Brain state TD] may correspond to [mental phenomena TD], which is the mental phenomena of "tiger dangerous!". Do you agree that the subject's brain matter will continue to move according to naturalistic patterns? If so, the subject's brain matter could arbitrarily shift from [brain state TD] to any number of other brain states.

      Let's say that [brain state RA] corresponds to the physical phenomena "running away" and [brain state PT] corresponds to the physical phenomena "pet tiger". In a naturalistic framework, is the subject's brain matter *in principle* more likely to shift from [brain state TD] to [brain state RA] than from [brain state TD] to [brain state PT]? If so, why?

      (to be continued...)

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    4. Let's shorten [brain state which corresponds to accurate mental phenomena] to [BSAMP], [brain matter which corresponds to evolutionarily-advantageous physical phenomena] to [BSEAPP], and [brain state which corresponds to evolutionarily-non-advantageous physical phenomena] to [BSENAPP]. I think an evolutionary process will only give correspondingly greater purchase (via mental experience) of reality to successive generations if organisms' brain matter is *in principle* more likely to shift from [BSAMP] to [BSEAPP] than from [BSAMP] to [BSENAPP].

      I don't think a naturalistic metaphysical framework provides any such principle. Unless accurate mental phenomena are *in principle* more likely than not to correspond to evolutionarily-advantageous behavior, there's no principled reason why later generations' mental phenomena would more accurately correspond to reality than earlier generations' mental phenomena. Consequently, an organism's presence at the end of a long evolutionary process is no promise that its mental phenomena will be rational or accurate. Even if human beings are at the end of a long evolutionary chain, that's no guarantee that our thoughts are likely to be rational or correspondent to reality in a metaphysically naturalistic framework.

      If my case is good, I'm basically arguing the same thing which Lewis did in "Miracles"- naturalism can't be rationally accepted. I'm merely adding that "being at the end of a long evolutionary process doesn't make naturalism any more rational to believe in."

      I think this is about as thorough a fleshing-out of my argument as I can provide, so please let me know if you find any holes. If I've demonstrated that naturalism doesn't provide a principle whereby accurate mental phenomena are inherently more likely than not to correspond to evolutionarily-advantageous behavior, I think I've taken the day.

      P.S. I do recognize speed limit signs and drive at speeds which are (roughly) correspondent to the speed limit, but I don't try to account for my mental phenomena naturalistically, so I don't have a problem. :-)

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    5. Hi Christian,

      Semantics means "meaning". Brain states are physical states of matter, but from the point of view of a mind they have meaning, or aboutness. They refer to some concept, whether abstract or physical. The physical aspect could considered to be analogous to symbols or syntax in a language.

      How semantics come from syntax is a contentious issue, and I have my own ideas which I have expressed elsewhere on this blog.

      The important thing to realise is that it's not arbitrary. By that, I mean not only that a specific mental state has a particular meaning, but that it could have no other meaning. As such, I disagree with your statement:

      "I'd say that mental phenomena *are* arbitrary inasmuch as nature isn't obliged to cause any particular mental phenomena by way of particular brain state."

      In a naturalistic world view, nature is pretty much deterministic (apart from quantum effects). Whatever mental phenomena we experience must be determined by the physical phenomena. There is no magic code for interpretation which could be otherwise. So we need to understand how this comes about.

      My view is that the semantics of a particular brain state arises out of how that brain state connects to other brain states. This is getting a little out of scope for this conversation, but I can sketch out a quick example.

      "Tiger is dangerous" is a compound idea composed of multiple concepts, including "tiger", the idea of having a property, and the idea of "danger".

      Let's focus on "danger".

      "Danger" is linked to "fear". "Fear" is linked to parts of the brain that produce adrenaline and induce the corresponding emotions. Activation of these emotions is linked to the response to flee.

      So the perception of a tiger which is believed to be dangerous triggers a response which can be understood in mechanical terms as an activation of various different brain patterns which inevitably trigger a response to flee.

      The terms "tiger", "dangerous", "fear", "flee" are in a sense just words we use to describe the subjective feelings we have when these brain patterns are activated.

      As such, it is incorrect to say that these brain patterns could refer to other interpretations such as those proposed by Plantinga.

      If you still have trouble with this, I urge you again to consider examples of mechanical systems which have internal representations of properties about the world and how the semantics of those representations influence physical outcomes.

      If you think that a naturalistic world view has problems with explaining how road signs affect behaviour, then consider that it ought to be possible to build an automated car which would obey the signs in much the same way as you do using visual sensors and information processing.

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    6. Hi Disagreeable,

      I apologize for my somewhat-delayed response. I trust that you still get some kind of notification, though, so I hope I can still count on a response from you. :-)

      I'd like to clarify what I think is a point of disagreement. You're referring to observed mental phenomena using philosophy-of-mind terminology like "semantics," which equal "aboutness." I think that's fine, but I think you may unintentionally be smuggling factors into a naturalistic metaphysical framework whose legitimacy in that framework hasn't been established.

      I'll demonstrate using your most recent comment. You say that "'tiger is dangerous' involves the concepts 'tiger,' 'property-having,' and 'danger.'" I agree. You focus on "danger" and say that "it's linked to 'fear,' which in turn links to 'adrenaline and corresponding emotions,' which links to the the physical phenomena 'fleeing.'" I agree that "tiger is dangerous" contains the described concepts. I believe, and I think you would agree, that individual parties may personally experience the "danger-fear-adrenaline-flee" in certain circumstances and that said parties may sensibly deduce a similar experience in other parties' mental phenomena when said other parties exhibit the physical phenomena of "fleeing." I think, though, that you may be making an unwarranted jump from "we see how this is evolutionarily advantageous in our own world" to "therefore this demonstrates a higher probability that accurate mental phenomena positively correspond to evolutionary advantage in a naturalistic metaphysical framework."

      We'll shorten "mental phenomena" to "MP" and "physical phenomena to "PP". You seem to be saying that "in some circumstances, an inherent connection exists from MP 'tiger' to MP 'dangerous' to MP-which-corresponds-to-PP 'adrenaline' to MP-which-corresponds-to-PP 'flee.'" Let's further shorten "PP correspondent to [MP]" to "PP of [MP]." If I'm correct, the "tiger"-to-"flee" connection chain can be properly rendered "PP of 'tiger' goes to PP of 'dangerous' goes to PP 'adrenaline' goes to PP 'flee'."

      Leaving aside "MP" and "PP" terminology, I think you're saying that "in some circumstances, an inherent connection exists from 'tiger' to 'dangerous' to 'adrenaline' to 'flee.'" I agree that such a connection sometimes exists- we observe it in the world- but I don't think there's any principled reason that it should exist in a naturalistic metaphysical framework. I don't see any principled reason that those physical phenomena would, in a naturalistic metaphysical framework, more likely connect to one another in that order than they would connect to other physical phenomena which form totally different chains. In fact, I'd say that each of the individual PP in the chain is much more likely to (in any given occurence) connect to other PP than to connect to the PP of the chain.

      I don't think that the chain you suggested is particularly likely to exist as a high-likelihood phenomenon in a naturalistic world. If the connection has no principled reason to frequently occur in a naturalistic metaphysical framework, it can hardly be relied upon as a consistent aid in survival and reproduction. Unless you think that physical phenomena in a naturalistic framework would relate to one another in a different way than I've suggested, I think the chain should be removed from our deliberations regarding physical phenomena in a naturalistic metaphysical framework.

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    7. Just for kicks, though, let's stipulate that the chain's physical phenomena are particularly likely to relate to one another. Even with this stipulation, I don't think that any organism's evolutionary fitness is, on the whole, particularly bolstered by the higher likelihood of a chain's occurrence. Let's return to Hominid Paul and the tiger. If the chain kicks in when Paul is near to and facing a hungry tiger, it helps him to survive. What happens, though, when he's near to and facing *away* from a hungry tiger when the chain kicks in? He experiences the phenomena "tiger - dangerous - adrenaline - flee" and turns to run... right into the maw of the hungry tiger.

      I think it's fair to say that "for every situation where a phenomena chain would be evolutionarily advantageous, there also exists a situation where the same chain would be equivalently evolutionarily disadvantageous." The existence of such phenomena chains in organisms' experience would only be inherently evolutionarily advantageous if a principle existed whereby said chains would more likely begin in advantageous situations than in disadvantageous situations. Absent such a principle, even the existence of such chains doesn't at all benefit evolutionary fitness.

      I still don't think there's any reason that accurate mental phenomena are more likely to correspond to evolutionarily advantageous physical phenomena than inaccurate mental phenomena are. If accurate and inaccurate mental phenomena correspond to equal evolutionary fitness (in terms of physical phenomena), there's no reason to suppose that any organism is particularly likely to accurately comprehend reality. Consequently, it's still insensible to consider metaphysical naturalism a rational choice.

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    8. Hi Christian,

      Apologies for my late reply also. I'm in the middle of an awkward relocation and am a bit stressed and sleep deprived at the moment.

      I think the distinction you make between mental phenomena (thoughts) and physical phenomena (adrenaline, fleeing) is not quite the distinction we ought to be focusing on. We need to think about how the meaning or semantics of thoughts relate to the physical activation of neurons.

      As far as I can see, there is no disagreement between us that the physical side of thinking (firing of particular neurons, etc) is physically causally effective, and so we ought to accept that that is fair game for natural selection. Where we disagree is on whether the meaning of the thoughts is naturally selectable.

      It should be clear to you that the meaning will indeed be naturally selected (albeit indirectly) if and only if the relationship between the physical structures in the brain and the semantics are necessary and non-arbitrary. In other words, if it is the case that *this* brain structure can only have *this* meaning, then I have been shown to be correct.

      In a deterministic naturalistic worldview, nothing is really arbitrary in this sense, as all phenomena can ultimately be explained in terms of more fundamental ones (until we hit the bedrock of the laws of physics). As such, naturalists will assume that the meaning of particular brain structures is necessary, and so the EAAN is not even slightly persuasive. By selecting for behaviour b_x, we are indirectly selecting for neural activation pattern n_x, which indirectly selects for mental events m_x.

      However, a naturalist still needs to give an account of where the meaning comes from, or at least acknowledge that this is a problem not yet solved.

      This is why I think you need to stop thinking about chains. What I'm talking about is a web. I think the best proposal to explain the semantics of a symbol (physical neural pattern) in the brain is that it arises from the structure and strength of the links to other symbols.

      For example, if I said to you that the concept X is associated closely with the concepts of "neck", "very tall", "herbivore", "Africa", "yellow", "patches", etc, you might have a fair chance of guessing that X is "giraffe".

      I think of this as similar to a concept map (http://en.wikipedia.org/wiki/Concept_map). As I traced out the links from tiger to danger to fleeing, etc, I was diagramming just a very few parts of a larger web of meaning. This web is always present in the brain, leading to a persistent belief that tigers are dangerous. It does not lead to a continuous behaviour of running away from tigers. For that behaviour to be triggered, you must have a belief that you see a tiger.

      Which is why your example of how this chain could be dangerous is the perfect example of why evolution would select for true beliefs. You imagine that Paul might turn around and flee towards a tiger behind him -- but he would only do this if he had a false belief that the tiger were in front of him. If evolution selects for true beliefs, this will not happen.

      I haven't really explained properly how meaning can arise from the web or concept map. That's another topic entirely, perhaps worthy of its own blog post. For now, I think it ought to be enough for me to explain that naturalism is indeed rational if we assume that semantics follow necessarily from physical structure. Even if this has not been proven, it's an entirely reasonable assumption, and in fact the only one consistent with naturalism. As such, naturalism is coherent, and the EAAN does not succeed.

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  7. Hi Disagreeable and Christian,

    I hope you won't mind me butting in. I substantially agree with Disagreeable, but I would put some things rather differently. Anyway, let me have a go at explaining things my way, and see if that helps.

    Christian wrote: "If everything in the naturalistic system is purely explicable in physical phenomena or by direct correspondence to physical phenomena, it's possible (and likely easier) to refer to all physical events in terms of physical phenomena instead of involving mental phenomena-related vocabulary."

    As I see it we model reality at various different levels of abstraction. Even when it's possible in principle to explain something at a lower level of abstraction, that doesn't mean it's practical to do so. It's probably possible in principle to give an atomic level account of a volcanic eruption. But such an account is not practical or useful. It's more useful to think at the macroscopic level, in terms of magma chambers, lava flows, etc.

    The same sort of thing goes for our mental models. Even if we could in principle explain a behaviour in terms of neurophysiological processes, that doesn't mean we can't also explain it in mental terms. And most of the time the mental level is much the more useful. It's very useful to be able to say, "Napoleon attacked because he believed the enemy was weak". The fact that this is the most useful way of modelling the brain for our purposes doesn't mean that Napoleon's behaviour wasn't the result of processes which can also be modelled (in principle) at the level of neurons and synapses, or at the atomic level, or at the level of the quantum wave function.

    [Continued...]

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    1. [...continued]

      Different levels of physical model tend to line up more neatly than do mental with physical models, because we can usually think of the entities at one physical level being made up of entities at a lower level, e.g. a chair is made up of molecules. Beliefs are not "made of" molecules (or of neurons and synapses), at least not in that straightforward way. The relationship of beliefs to brain states is more fuzzy and difficult to describe than that. In the case of chairs, I think we can easily see that the chair and its molecules are (in a sense) the same thing, so when you do something to a chair you necessarily do something to its molecules, and vice versa. No one is tempted to say, "OK. You moved the molecules. Now explain how the chair got moved." But people are tempted to say, "OK. You can change the brain states. Now explain how you can change the mental states (e.g. beliefs)." But changing brain states and changing corresponding mental states is making the same change, albeit we're talking about the change in two different ways.

      Consider the example of a computer program stored in memory (RAM). The program isn't "made of" physical stuff, but it supervenes on the physical stuff of the memory, in something like the way that a mental state supervenes on physical states. You wouldn't say, "OK. You can change the memory. Now explain how you can change the program. Or, "OK. The memory state can affect the behaviour of the computer. Now explain how the program can affect the behaviour of the computer." Changing the memory where the program resides and changing the program are the same change.

      I suspect that the discussion of beliefs is often confounded by thoughts of consciousness. But since Christian and Plantinga haven't made an argument about consciousness, I think we're entitled to leave that out of consideration. Beliefs are mental states, not conscious experiences. And they don't have to be accompanied by conscious experiences. I have a continuing belief that the Earth is round, but I'm not constantly thinking, "The Earth is round". And we often act on our beliefs without any conscious thought. I may feel rain, come to believe that it's raining, and put up my umbrella, all without any conscious reflection on the subject.

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    2. Thanks for adding to the conversation, Richard. I'd mostly agree with you, but I think it may be possible to see mental states as something inherently separate from physical states.

      As I believe in the CTM (which I believe you do to), I think the same mental states could be produced by entirely dissimilar physical states (e.g. an electronic brain), so there is something more going on than simply describing things at different levels, in my view.

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    3. Hi Disagreeable. You wrote:

      As I believe in the CTM (which I believe you do to), I think the same mental states could be produced by entirely dissimilar physical states (eg an electronic brain), so there is something more going on than simply describing things at different levels, in my view.

      I'm not saying that a given mental description (like "He believes the Earth is round") can only be appropriate to one specific brain/AI state. Many different brain/AI states could be appropriately described in that way. Roughly speaking, it's the way that the state arose and the way that it causes the system to behave that make that description appropriate.

      By way of analogy, when I say, "The cat sat on the mat", I'm not committed to any particular arrangement of atoms in the cat or the mat. Many differerent arrangements of atoms could appropriately be described by that macroscopic description. Likewise, when I say "My PC's recycle bin is full", there are many possible physical states my PC could be in, e.g. many different ways the bin could be distributed over my hard disk. When I talk about my recycle bin, I'm talking at the software level, which is a more abstract level than the hardware level. Hardware details are abstracted out.

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    4. We probably agree on all that. I'm just accounting for why my explanation might be a bit different.

      But now I'm going to say something you might disagree with. I think the CTM commits you to dualism, which is a dirty word in the eyes of most naturalists.

      But there are different kinds of dualism, and some of them are compatible with naturalism. For example, mathematical platonism is the view that mathematical objects exist but are not physical. This then is dualism of a kind, because it claims that both physical objects and abstract objects exist, and they are made of different stuff. This is not at all in conflict with naturalism because mathematical objects have no direct causal effect on physical objects.

      I am a mathematical platonist, and I think that the mind is a mathematical object.

      But then, I think the universe is ultimately a mathematical object too, so really my dualism is only a temporary explanatory step on the journey to an ultimate mathematical monism.

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    5. Interesting. When I read views like yours I have great difficulty deciding whether there is a substantive difference between us, or do you just have (from my point of view) a misguided view of language and a strange way of speaking. That said, the distinction between substantive and linguistic can be a fuzzy one. I have a Wittgensteinian view of language, and like Wittgenstein I find much of philosophy to be undermined by "the bewitchment of our intellect by our language".

      Take, for example, assertions like "numbers exist" and "numbers are objects", which are things a mathematical platonist is inclined to say. I'm usually inclined to see such assertions as meaningless and not even wrong. But the more the platonist reifies his mathematical objects the more he seems to me to be making a substantive error, believing in things that don't exist. Sometimes this reification consists of speaking of a "realm" of mathematical objects. You seem to go even further, when you speak of such objects being "made of ... stuff" (albeit a different sort of stuff).

      As I see it, number-words are useful words for expressing certain sorts of relationships in our models of reality, and for constructing axiomatic systems of thought. It's in the nature of our language that we sometimes find it useful to use words like "number", "set", etc, as nouns, as if they refer to objects. But it's unhelpful to think of them as referring to objects in any deeper sense. Reifying them in that deeper way inclines us to see too great a similarity between physical objects and mathematical "objects". It seems that this then inclines you to put them on the same level and compare them, leading you to call yourself a dualist. To me this is a kind of category error: physical objects and mathematical "objects" (in so far as we can even call them that) are not commensurable in any useful way.

      I think it's fairly obvious that not all our words refer to objects. You probably don't think that prepositions like "for" and "of" refer to objects. These words are used to describe relationships of various sorts. It may help to see mathematical words as being more like this than like words that refer to objects.

      In the end you say that you're a monist after all! So again I'm encouraged to think that perhaps there's no substantive difference between us. But calling the mind and the universe "mathematical objects" seems meaningless to me.

      P.S. I've just noticed that you've posted a new OP devoted to this subject. Feel free to copy your comment and mine to that thread if you think it would be helpful. We could continue the discussion there (though I'm not sure I'll have time for much more).

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    6. Hi Richard,

      I'll just comment briefly here.

      I'm extremely sympathetic to the Wittgensteinian view you express. I don't really think there's a fact of the matter as to whether mathematical objects exist or not, but I do think that it is useful to think of them that way and I do think it helps to resolve some problems in the philosophy of mathematics and other areas.

      I think the whole concept of existence in general is dubious at best when not applied to physical objects, and breaks down when you try to apply it to questions such as whether mathematical objects, universes, or consciousness exist.

      The word "stuff" as I intend it simply means the fundamental essence of what an object is made of. Since abstract objects are not physical, their "stuff" is not material but formed of relations, etc. You can view this as a metaphorical if not a literal usage of the word stuff. As such, I don't think I'm actually going further than other Platonists.

      I don't believe it is helpful to think of a distinct "realm" of mathematical objects. That implies a physical space, which is not my intuition at all. I think of them as existing in an entirely different way to physical objects.

      I am a monist, but of a different kind than you, I suspect. I think that only mathematical objects fundamentally exist, and I think the universe and the mind are both instances of this. For the universe, you can think of ontic structural realism. For the mind, you can think of a self-aware algorithm in accordance with the computational theory of mind.

      It would be great to hear your thoughts on my top level post exploring some of these ideas. I intend to explain my ideas about what the universe is and why it exists at some future date.

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  8. From your reply it sounds as if the difference between us is entirely or almost entirely linguistic. But I find your language unnecessarily confusing. I think it's going to be very difficult for you to engage in constructive discussions of these subjects when you speak this way. Most people are not as linguistically understanding as I am. ;)

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    1. You might be right.

      But everything I write is bearing in mind a larger thesis I have in mind. The language I use (and mathematical Platonism in particular) may be necessary to explain that larger thesis.

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