The Open Mind

Cogito Ergo Sum

Substance Dualism, Interactionism, & Occam’s razor

with 13 comments

Recently I got into a discussion with Gordon Hawkes on A Philosopher’s Take about the arguments and objections for substance dualism, that is, the position that there are actually two ontological substances that exist in the world: physical substances and mental (or non-physical) substances.  Here’s the link to part 1, and part 2 of that author’s post series (I recommend taking a look at this group blog and see what he and others have written over there on various interesting topics).  Many dualists would identify or liken this supposed second substance as a soul or the like, but I’m not going to delve into that particular detail within this post.  I’d prefer to focus on the basics of the arguments presented rather than those kinds of details.  Before I dive into the topic, I want to mention that Hawkes was by no means making an argument for substance dualism, but rather he was merely pointing out some flaws in common arguments against substance dualism.  Now that that’s been said, I’m going to get to the heart of the topic, but I will also be providing evidence and arguments against substance dualism.  The primary point raised in the first part of that series was the fact that just because neuroscience is continuously finding correlations between particular physical brain states and particular mental states, this doesn’t mean that these empirical findings show that dualism is necessarily false — since some forms of dualism seem to be entirely compatible with these empirical findings (e.g. interactionist dualism).  So the question ultimately boils down to whether or not mental processes are identical with, or metaphysically supervenient upon, the physical processes of the brain (if so, then substance dualism is necessarily false).

Hawkes talks about how the argument from neuroscience (as it is sometimes referred to) is fallacious because it is based on the mistaken belief that correlation (between mental states and brain states) is equivalent with identity or supervenience of mental and physical states.  Since this isn’t the case, then one can’t rationally use the neurological correlation to disprove (all forms of) substance dualism.  While I agree with this, that is, that the argument from neuroscience can’t be used to disprove (all forms of) substance dualism, it is nevertheless strong evidence that a physical foundation exists for the mind and it also provides evidence against all forms of substance dualism that posit that the mind can exist independently of the physical brain.  At the very least, it shows that the prior probability of minds existing without brains is highly unlikely.  This would seem to suggest that any supposed mental substance is necessarily dependent on a physical substance (so disembodied minds would be out of the question for the minimal substance dualist position).  Even more damning for substance dualists though, is the fact that since the argument from neuroscience suggests that minds can’t exist without physical brains, this would mean that prior to brains evolving in any living organisms within our universe, at some point in the past there weren’t any minds at all.  This in turn would suggest that the second substance posited by dualists isn’t at all conserved like the physical substances we know about are conserved (as per the Law of Conservation of Mass and Energy).  Rather, this second substance would have presumably had to have come into existence ex nihilo once some subset of the universe’s physical substances took on a particular configuration (i.e. living organisms that eventually evolved a brain complex enough to afford mental experiences/consciousness/properties).  Once all the brains in the universe disappear in the future (after the heat death of the universe guarantees such a fate), then this second substance will once again disappear from our universe.

The only way around this (as far as I can tell) is to posit that the supposed mental substance had always existed and/or will always continue to exist, but in an entirely undetectable way somehow detached from any physical substance (which is a position that seems hardly defensible given the correlation argument from neuroscience).  Since our prior probabilities of any hypothesis are based on all our background knowledge, and since the only substance we can be sure of exists (a physical substance) has been shown to consistently abide by conservation laws (within the constraints of general relativity and quantum mechanics), it is more plausible that any other ontological substance would likewise be conserved rather than not conserved.  If we had evidence to the contrary, that would change the overall consequent probability, but without such evidence, we only have data points from one ontological substance, and it appears to follow conservation laws.  For this reason alone, it is less likely that a second substance exists at all, if it isn’t itself conserved as that of the physical.

Beyond that, the argument from neuroscience also provides at least some evidence against interactionism (the idea that the mind and brain can causally interact with each other in both causal directions), and interactionism is something that substance dualists would likely need in order to have any reasonable defense of their position at all.  To see why this is true, one need only recognize the fact that the correlates of consciousness found within neuroscience consist of instances of physical brain activity that are observed prior to the person’s conscious awareness of any experience, intentions, or willed actions produced by said brain activity.  For example, studies have shown that when a person makes a conscious decision to do something (say, to press one of two possible buttons placed in front of them), there are neurological patterns that can be detected prior to their awareness of having made a decision and so these patterns can be used to correctly predict which choice the person will make even before they do!  I would say that this is definitely evidence against interactionism, because we have yet to find any cases of mental experiences occurring prior to the brain activity that is correlated with it.  We’ve only found evidence of brain activity preceding mental experiences, never the other way around.  If the mind was made from a different substance, existing independently of the physical brain (even if correlated with it), and able to causally interact with the physical brain, then it seems reasonable to expect that we should be able to detect and confirm instances of mental processes/experiences occurring prior to correlated changes in physical brain states.  Since this hasn’t been found yet in the plethora of brain studies performed thus far, the prior probability of interactionism being true is exceedingly low.  Additionally, the conservation of mass and energy that we observe (as well as the laws of physics in general) in our universe also challenges the possibility of any means of causal energy transfer between a mind to a brain or vice versa.  For the only means of causal interaction we’ve observed thus far in our universe is by way of energy/momentum transfer from one physical particle/system to another.  If a mind is non-physical, then by what means can it interact at all with a brain or vice versa?

The second part of the post series from Hawkes talked about Occam’s razor and how it’s been applied in arguments against dualism.  Hawkes argues that even though one ontological substance is less complex and otherwise preferred over two substances (when all else is equal), Occam’s razor apparently isn’t applicable in this case because physicalism has been unable to adequately address what we call a mind, mental properties, etc.  My rebuttal to this point is that dualism doesn’t adequately address what we call a mind, mental properties, etc., either.  In fact it offers no additional explanatory power than physicalism does because nobody has proposed how it could do so.  That is, nobody has yet demonstrated (as far as I know) what any possible mechanisms would be for this new substance to instantiate a mind, how this non-physical substance could possibly interact with the physical brain, etc.  Rather it seems to have been posited out of an argument from ignorance and incredulity, which is a logical fallacy.  Since physicalism hasn’t yet provided a satisfactory explanation for what some call the mind and mental properties, it is therefore supposed by dualists that a second ontological substance must exist that does explain it or account for it adequately.

Unfortunately, because of the lack of any proposed mechanism for the second substance to adequately account for the phenomena, one could simply replace the term “second substance” with “magic” and be on the same epistemic footing.  It is therefore an argument from ignorance to presume that a second substance exists, for the sole reason that nobody has yet demonstrated how the first substance can fully explain what we call mind and mental phenomena.  Just as we’ve seen throughout history where an unknown phenomena is attributed to magic or the supernatural and later found to be accounted for by a physical explanation, this means that the prior probability that this will also be the case for the phenomena of the mind and mental properties is extraordinarily high.  As a result, I think that Occam’s razor is applicable in this case, because I believe it is always applicable to an argument from ignorance that’s compared to an (even incomplete) argument from evidence.  Since physicalism accounts for many aspects of mental phenomena (such as the neuroscience correlations, etc.), dualism needs to be supported by at least some proposed mechanism (that is falsifiable) in order to nullify the application of Occam’s razor.

Those are my thoughts on the topic for now.  I did think that Hawkes made some valid points in his post series — such as the fact that correlation doesn’t equal identity or supervenience and also the fact that Occam’s razor is only applicable under particular circumstances (such as when both hypotheses explain the phenomena equally, good or bad, with one containing a more superfluous ontology).  However, I think that overall the arguments and evidence against substance dualism are strong enough to eliminate any reasonable justification for supposing that dualism is true (not that Hawkes was defending dualism as he made clear at the beginning of his post) and I also believe that both physicalism and dualism explain the phenomena equally well such that Occam’s razor is applicable (since dualism doesn’t seem to add any explanatory power to that already provided by physicalism).  So even though correlation doesn’t equal identity or supervenience, the arguments and evidence from neuroscience and physics challenge the possibility of any interactionism between the physical and supposed non-physical substance, and it challenges the existence of the second substance in general (due to it’s apparent lack of conservation over time among other reasons).
Advertisements

13 Responses

Subscribe to comments with RSS.

  1. Even more damning for substance dualists though, is the fact that since the argument from neuroscience suggests that minds can’t exist without physical brains, this would mean that prior to brains evolving in any living organisms within our universe, at some point in the past there weren’t any minds at all.

    I am doubtful of that.

    It could be that minds use brains to express themselves in ways that affect the material world. But that would allow the possibility that minds can exist without brains, though they would not then be able to express themselved materially — though perhaps they could express themselves in other ways.

    To be clear, I am not a dualist. I am just pointing out a weakness in the argument.

    Neil Rickert

    October 31, 2015 at 3:36 pm

    • You are doubtful of what exactly? That neuroscience suggests that minds can’t exist without physical brains? That, because neuroscience suggests that minds can’t exist without physical brains, that “mind substance” wouldn’t be conserved in the absence of brains?

      I never said that minds weren’t possible without brains. I simply pointed out that the arguments from neuroscience suggest that minds aren’t likely to exist without physical brains, and coupled with the fact that we lack any observed instances of minds existing without brains, this suggests that minds can’t exist without physical brains. It doesn’t prove that this is the case, but merely suggests it. This means that based on all our background knowledge, the prior probability that minds can exist without brains is very low. One would need evidence to support the claim that minds can exist without physical brains in order to increase the consequent probability of dualism. Until we see that evidence, all we have are extremely low priors for dualism, and therefore no good reason to believe that dualism is true.

      So, what weakness did you see in the argument? I’m just looking for clarification. Perhaps you misunderstood me, or perhaps I am misunderstanding your comment.

      Lage

      October 31, 2015 at 4:38 pm

      • You are doubtful of what exactly? That neuroscience suggests that minds can’t exist without physical brains?

        Yes, precisely.

        Neuroscientists can, of course, jump to the conclusion that minds cannot exist without brains. But they cannot provide supporting evidence. It is all confirmation bias.

        My own view is that minds don’t actually exist at all. That is to say, our “mind talk” is metaphorical.

        Neil Rickert

        October 31, 2015 at 4:57 pm

      • Neuroscientists aren’t jumping to conclusions when they presume that minds do not exist without brains. It is based off of the fact that of all the evidence of minds we’ve found thus far, they are all tied to the processes of physical brains. This is supporting evidence. It isn’t confirmation bias at all because they aren’t ignoring other data to support their conclusion. They are including all the data they have available. As for minds not existing, even if you don’t think minds exist per se, that’s likely mostly just a semantic issue. Whatever you want to call the means by which you have conscious thought, is what most people refer to as minds. I doubt you believe that we don’t have conscious thought. At best, you probably just want to call it something else which is fine. That doesn’t change the fact that we have what we call conscious thought, nor does it change the fact that we have a physical substrate that seems to produce it (i.e. the brain).

        Lage

        October 31, 2015 at 6:35 pm

      • Neuroscientists aren’t jumping to conclusions when they presume that minds do not exist without brains.

        Your use of the word “presume” is pretty much an admission that it is jumping to a conclusion.

        Neil Rickert

        October 31, 2015 at 6:47 pm

      • Sure, then I’ll change “presume” to “infer from the evidence”. Jumping to a conclusion implies that there isn’t any merit for the conclusion. There is in this case, and as such the conclusion is inferred from the evidence.

        Lage

        October 31, 2015 at 6:49 pm

      • Sure, then I’ll change “presume” to “infer from the evidence”.

        However, it isn’t a logical inference.

        Neil Rickert

        October 31, 2015 at 7:54 pm

      • Actually it is a logical inference — based on Bayesian probability logic. It’s just not a logical proof by any means. One can however assign prior probabilities of one hypothesis compared to another (e.g. “minds only exist as the product of physical brains” vs. “(at least some if not all) minds exist independently from physical brains”) and then logically infer which hypothesis is most likely to be true based on those prior probabilities (as well as by logically inferring the frequency based prior probabilities you start with based on the background knowledge). Based on our background knowledge, we can see that the frequency of minds we’ve found existing as the product of physical brains, versus those that don’t are thus far 100% the former and 0% the latter. So then we can argue a fortiori that the prior probability of minds only existing as the product of physical brains as opposed to the alternative hypothesis is at least 99%. The consequent probability for the second hypothesis (dualism) could compensate for such a low prior in light of new evidence, but for now, the probability of having the evidence we do have from neuroscience and so forth is significantly higher on physicalism than dualism.

        Lage

        October 31, 2015 at 9:02 pm

  2. For example, studies have shown that when a person makes a conscious decision to do something (say, to press one of two possible buttons placed in front of them), there are neurological patterns that can be detected prior to their awareness of having made a decision and so these patterns can be used to correctly predict which choice the person will make even before they do!

    I think you refer to the Libet experiment. This experiment and especially its interpretation saying that the brain is activated before the decision has got a lot of critics and I think they are right. Just think, when does a decision start? When you press the button? When think about to press the button? When your neurons got activated?

    Don’t get me wrong I am not a dualist. But quoting the Libet experiment is just not a good argument. I think we have some contradicting intuitions (at least I have them): 1. We think that the mind should have emerged out of mindless material. That suggest for example our believes about evolution. 2. We think that the Mind is not reducible to the Brain (of cause that’s a point to discuss but for me at least philosophical discussion points to the nonreducibility of the mind) 3. We think that the material realm is closed and that the only causation is material causation but also that our mental states cause our behavior.

    I try to work on a non-reductive naturalistic theory of mind. That would be my favorite theory. A theory that gives the mind the place it deserves without falling into dualism.

    Danny Krämer

    November 3, 2015 at 10:42 am

    • Hey Danny,

      Thanks for taking the time to read and comment!

      I think you refer to the Libet experiment. This experiment and especially its interpretation saying that the brain is activated before the decision has got a lot of critics and I think they are right.

      I’m referring to multiple studies, though the Libet experiment would be included within that group of studies (as well as those by Kuhn, Brass, Matsuhashi, et al). I haven’t seen one single study show that the neural activity correlates of conscious thought occur AFTER a person is conscious of the thought. Rather, I’ve only seen studies showing that neural activity occurs BEFORE the patient is aware of the thought in question (or else it is undetermined). The Libet experiment simply clarified some of the quantitative details regarding how much time passes after the correlated neural activity occurs before the patient is aware of what the neural activity produced. However, many experiments have been performed since Libet’s and have further reinforced the position that (at least many) neurological correlates precede consciousness pertaining to those correlates.

      But quoting the Libet experiment is just not a good argument.

      And I didn’t quote that experiment specifically. I simply referred to “many studies” that show similar results and Libet’s results are included in those results which have since been replicated and also found in new designed experiments that test for the same thing (with better controls over the factors that were presented by Libet’s critics). Again, there are multiple studies and either the timing sequence is unknown or it is PRIOR to conscious deliberation/thought, which is positive evidence against any kind of downward causal interaction between the “mind” and brain — since we only have evidence for one causal direction and not the other.

      I think we have some contradicting intuitions (at least I have them): 1. We think that the mind should have emerged out of mindless material. That suggest for example our believes about evolution. 2. We think that the Mind is not reducible to the Brain (of cause that’s a point to discuss but for me at least philosophical discussion points to the nonreducibility of the mind) 3. We think that the material realm is closed and that the only causation is material causation but also that our mental states cause our behavior.

      For 1, that the mind would emerge out of matter is a prediction that results from our analysis of evolution and natural selection (as you state). For 2, some people think that the mind is not reducible to the brain, but I’ve not seen any good arguments that defend this claim. Most arguments that are employed to try to defend this are the result of poorly defining terms, defining certain terms without showing how those definitions were derived, and from introspective experience of how things “seem to be” (qualia, richness of experience, etc.). For 3, some people find it convenient to say that our mental states cause our behavior, but there simply isn’t any evidence that mental states are any different than brain states. They seem to be different descriptions of the same thing (at best) or the term “mental states” seems to be superfluous (to me anyway). In general anyway, I don’t think that using intuitions is a reliable means for sorting out this mess or solving the problem. I think it has been human intuitions that have created much of the mind-body problem in the first place. We must realize that the richness of our experience which produces some of these intuitions likely results from the fact that the brain models reality in a very particular and complex way with many, many parallel operations occurring with trillions of synapses (billions of neurons) at the same time. So I don’t expect our intuitions to be valuable in determining how the brain produces intuitions in the first place (or any other thought that pops into consciousness). That is, to use a heuristic model (like intuition) to try and solve a problem about an organ that is so vastly complex is misguided. We can’t take the easy route with a problem bearing this level of complexity, as it is likely to steer us off course, perhaps in search of an answer to a question that was not formulated correctly in the first place. I think it would be analogous to our using intuition to infer that biological complexity must have been designed, rather than evolved through natural selection. As the evidence has thoroughly demonstrated, evolution through natural selection is the most effective explanation and the most supported explanation based on the large number of (confirmed) predictions that result from it. Since human intuition was wrong about the origin of biological complexity, then it is likely our intuitions are wrong about the origin of mental complexity (brain complexity).

      I try to work on a non-reductive naturalistic theory of mind.

      I’m just trying to follow where the evidence is leading us and using our past experience and methodological success as a guide/argument for determining the likelihood of physicalism versus dualism. As I’ve said here and elsewhere, I just don’t think that dualism has anything to offer other than saying that it is something other than “physicalism”.

      Lage

      November 3, 2015 at 5:31 pm

      • So as it seems you are sort of elminiatie materialist? I can at least understand reductive materialism but I could never understand eliminative materialism. You said you don’t believe that our mental states cause our behavior. But if that is not the case then a lot of our everyday beliefs are false. Then i.e. I did not intend to write this comment. It just happened to me (in some strange way). Even the talk of truth is not going to work. If we don’t have believes then we can’t have truth either.

        You say that the evidence leads us to such a eliminative stance. I don’t think so. There are a lot of works in psychology, cognitive science and even neurophysiology that opt against a reduction of the mind to neurophysiological going-ons. I mean you are biased in the way that you think all evidence there is leads to eliminative materialism. (At least so it seems to me.) But I can’t see why this should be so.

        And the worst argument for eliminative materialism is that we will find a perfect neurophysiology/psychology that will replace our nowadays psychology so we don’t have to talk about mental states in mental vocabulary. I just don’t even see how such a psychology would look like. Defending eliminative materialism due to the hope for a future psychology is to explain you-know-not-what by you-know-not-what.

        Anyways thanks for commenting on my thoughts. Just got into all this philosophy things in the web and I really appreciate it. Greetings.

        Danny Krämer

        November 3, 2015 at 7:56 pm

      • So as it seems you are sort of elminiatie materialist?

        I wouldn’t necessarily consider myself to be an eliminativist, but rather more of a revisionary materialist than either a pure eliminativist or pure reductionist — because I believe that the concept of “mental states” will need to undergo some revision before it is reducible to physical phenomena. How we have “mental states” defined currently, seems to also have dualist presuppositions or other implicit intuitions based on what I believe to be an introspective illusion. However, I do believe that at least some concepts that we currently employ in our theories will likely have to be abandoned, including likely eliminativism concerning qualia (as Dennett and Rey have proposed). So I’m kind of a mix between an eliminativist (minor) and a revisionary materialist (major) — though I don’t like the labels because they are too broad in many cases. Keep in mind that eliminativists are also a kind of reductionist, but they simply posit that some aspects or concepts within certain theories (such as within folk psychology) have to be abandoned in order to achieve the reductionist explanation properly. Just as concepts like phlogiston and demon-caused illnesses were eliminated rather than revised or formalized, eliminativists believe that at least some concepts within folk psychology will need to be eliminated prior to reducibility of what people call mental phenomena. I don’t think that it is unreasonable to expect an elimination of at least some concepts that we take for granted. We’ve already done this in physics several times over. One intuition that nobody would deny in their subjective experience is the intuition that an object has a definite location in time and space, however this intuition was disproven by quantum mechanics as well as relativity. It’s simply because our everyday experience is at a fixed scale and moving at a relatively small range of speeds that we don’t notice this fundamental nature of reality. It took a lot of technological advancement and many years to be able to probe those domains with fast speeds and extremely small experimental “probes” to reveal this fundamental nature of reality. So we had to abandon the many thousand year old assumption/intuition that time is absolute and that everything exists in a particular location in space and time. Since this was perhaps the most fundamental concept we’ve had to abandon (our very conception of time and space), honestly it makes eliminativism of folk psychology look small in comparison. More importantly however, is the fact that this precedent increases the prior probability that we are wrong about many of our other intuitions (such as those in folk psychology). So we must keep that in mind moving forward.

        But if that is not the case then a lot of our everyday beliefs are false. Then i.e. I did not intend to write this comment. It just happened to me (in some strange way).

        Yes, this may be the case. Just like even though we intuit that we have free will (in a classical sense), neuroscience and physics shows us how this can’t be so because every instance of behavior-generating activity in our brains are governed by electro-chemical laws of nature (so far as science has shown us). It may be that we can still use concepts like beliefs and intentions in everyday talk, but at least some of these concepts will have to be abandoned in a reductionist explanation — even if they are still valuable for pragmatic purposes. Just as it is valuable to assume that I have free will (even though science suggests I don’t) because it is pragmatically useful to pretend I have free will.

        Even the talk of truth is not going to work. If we don’t have believes then we can’t have truth either.

        This is only (possibly) true if one eliminates propositional knowledge, but philosophers such as Dennett are eliminativists of qualia, but not of propositional knowledge. Rather, they are non-reductionists when it comes to propositional knowledge. So it isn’t all or none. There are varying degrees of what eliminativists posit should be eliminated. And again, this only effects reductionism of various phenomena. It doesn’t mean we have to abandon our pragmatic everyday usage of these concepts (truth, belief, etc.).

        You say that the evidence leads us to such a eliminative stance. I don’t think so….I mean you are biased in the way that you think all evidence there is leads to eliminative materialism. (At least so it seems to me.)

        I never said the evidence leads us to an eliminative stance. Rather I said that the evidence leads us away from dualism and toward physicalism (whether reductionist, eliminativist, revisionary, etc.). Though I do think that the evidence has shown that our intuitions are often incorrect, which is certainly relevant to which brand of physicalism is most likely to succeed.

        And the worst argument for eliminative materialism is that we will find a perfect neurophysiology/psychology that will replace our nowadays psychology so we don’t have to talk about mental states in mental vocabulary. I just don’t even see how such a psychology would look like.

        I agree that this would be a bad argument to simply say that we will one day find a perfect school of thought to replace the one we have, however it doesn’t matter whether or not we can see what such a future psychology would look like (if this happens) because our inability to imagine something doesn’t mean that something isn’t in fact true. Again, we can make the same kinds of comments about physics after seeing how it’s changed so much over the last 100 years (with QM, relativtiy, etc.).

        Anyways thanks for commenting on my thoughts. Just got into all this philosophy things in the web and I really appreciate it. Greetings.

        No problem! Thanks for commenting as well and discussing this topic more. Peace!

        Lage

        November 4, 2015 at 10:48 am

      • I really apreciated the exchange but I think the dialectic of the arguments gets now too widespread for a wordpress comment section. Maybe we can discuss some other topic soon or the same topic in another post. Until then thanks!

        Danny Krämer

        November 4, 2015 at 4:34 pm


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: