Why Is Identity Important in the Physicalism/Dualism Debate?

Post Author: Bill Pratt

In previous posts we have surveyed the physicalist and dualist positions with regard to human beings.  Now it is time to start looking at arguments for the dualist position.  Before we start to defend dualism, we need to introduce the concept of identity, which will be an extremely important concept in the debate.

The law of identity simply states that A is A.  Yes, it’s that simple, but we need to draw out some implications from this law.  Philosopher J. P. Moreland helps us understand with the following example:

Suppose you want to know whether J. P. Moreland is Eileen Speik’s youngest son.  If J. P. Moreland is identical to Eileen Speik’s youngest son (everything true of one is true of the other), then in reality we are talking about one single thing – J. P. Moreland, who is Eileen Speik’s youngest son.  However, if even one small thing is true of J. P. Moreland and not true of Eileen Speik’s youngest son, then these are two entirely different people.  Furthermore, J. P. Moreland is identical to himself and not different from himself.  So, if J. P. Moreland is not identical to Eileen Speik’s youngest son, then in reality we must be talking about two things, not one.

Where does this example take us?  Moreland explains:

This illustration suggests a truth about the nature of identity known as Leibniz’s Law of the Indiscernibility of Identicals: For any entities x and y, if x and y are identical (they are really the same thing – there is only one thing you are talking about, not two), then any truth that applies to x will apply to y as well.  This suggests a test for identity: If you could find one thing true of x not true of y, or vice versa, then x cannot be identical to (be the same thing as) y.  Further, if you could find one thing that could possibly be true of x and not y (or vice versa), even if it isn’t actually true, then x cannot be identical to y.

Hopefully you have followed along, because now Moreland explains why this matters to the mind/body debate:

Physicalists are committed to the claim that alleged mental entities are really identical to physical entities, such as brain states, properties of the brain, overt bodily behavior, and dispositions to behave (for example, pain is just the tendency to shout “Ouch!” when stuck by a pin, instead of pain being a certain mental feel).  If physicalism is true, then everything true of the brain (and its properties, states, and dispositions) is true of the mind (and its properties, states, and dispositions) and vice versa.  If we can find one thing true, or even possibly true of the mind and not of the brain, or vice versa, then dualism is established.  The mind is not the brain.

At this point, it is critical to note that it is not enough for the physicalist to show that mental and physical entities in the human brain/mind are in a causal relation or are constantly conjoined. 

It may be that brain events cause mental events or vice versa: Having certain electrical activity in the brain may cause me to experience a pain; having an intention to raise my arm may cause bodily events.  It may be that for every mental activity, a neurophysiologist can find a physical activity in the brain with which it is correlated.  But just because A causes B (or vice versa), or just because A and B are constantly correlated with each other, that does not mean that A is identical to B.

Therefore, and this is critical, physicalism cannot be established on the basis that mental states and brain states are causally related or constantly conjoined with each other in an embodied person.  Physicalism needs identity to make its case, and if something is true, or possibly true of a mental substance, property, or event that is not true or possibly true of a physical substance, property, or event, then physicalism is false.

In future posts, we will look at whether mental states and brain states are truly identical.  Stay tuned!!

18 thoughts on “Why Is Identity Important in the Physicalism/Dualism Debate?”

  1. Moreland: If physicalism is true, then everything true of the brain (and its properties, states, and dispositions) is true of the mind (and its properties, states, and dispositions) and vice versa.

    Whoop! Whoop! Whoop! (Supposed to be sirens going off.) Strawperson alert! Is there a materialist who makes this claim? Seems to me Moreland’s entire argument will hinge on this so it is pretty key. Can you cite someone saying it, or does Moreland provide reference for what “physicalism” claims this to be?

    I can see numerous reasons why a materialist would NOT say this—I am trying to see in context where one did say it.

    If no reference is provided, I will presume this (yet again) is an argument built on straw. Easy enough to burn down; not really a “tough question.”

  2. Ah…exactly as I feared. No citations. So when a materialist uses vernacular—such as saying, “I changed my mind” the dualist can scream out: “HA! You didn’t really change brains—therefore dualism is false!”

    Nothing to see here. Just another strawman argument.

  3. Not having read the book, I can still predict exactly where this is going: fallacious substitution in opaque contexts and a trampling of the content/vehicle distinction.

    If and when that happens I’ll re-unlurk and make several self-congratulatory noises.

    If it doesn’t happen it means they have, against all odds, come up with an actual argument I haven’t seen before, so I will have learned something, so it will be win-win.

  4. DagoodS is right. This is clearly a strawman argument, and I’m surprised that JP Moreland would make such an obvious mistake. The brain and mind are not identical. They are two very distinct things, and, as Dagoods said, I don’t know a single materialist who would make the claim that they are the same. Brain states are just that, states of the brain. The feeling of pain you experience when poked with a pin is different from the physical process happening at the biological level that is responsible for the experience. Therefore, Leibniz’s Law of the Indiscernibility of Identicals, which seems to be the crux of Moreland’s argument here, is invalid in this case.

    This is logical smoke and mirrors, and I hope other readers will see through this.

  5. Ah… exactly as I feared. Another skeptic who is too lazy to read primary sources and is content to criticize something they know nothing about.

    Nothing to see here. Just another strawman argument.

  6. Bill Pratt, surely you could spend 2 mins typing out the reference from the book on your desk, instead of requiring Dagoods to spend $50 ?

  7. No no no, I never said they cannot be reduced to physical entities. They can be traced back to physical entities, e.g. vision to the optic nerve, sensation of pain in the nerves, and feelings of anger in parts of the brain. But your claim was that they are identical. Obviously, the feeling of anger is not itself the exact same as the electrical impulses that causes it, but we have no reason to believe it can occur without the physical processes (in this case, the biological processes in the brain).

    The fact that intangible things such as feelings, thoughts, and concepts exist does not mean there is something beyond the physical world that we live in. I can see the appeal in making this argument, but everything we know about biology, chemistry, neuroscience, psychology, and other related fields tells us that we have no reason to put some supernatural label on these things.

  8. Bill Pratt: Another skeptic who is too lazy to read primary sources…

    Er…um…what? Didn’t I ask for a citation to a “primary source”—specifically a materialist making the claim Moreland says materialists do? How can you accuse me of being “too lazy” to read that which you refuse to provide?

    Bill Pratt, I don’t know what “primary source” to read, unless you tell me. If you look back at my first comment, I did ask. Moreland is a secondary source as he is (supposedly) citing what someone else—the primary source—said. Why waste the time going through the secondary source? Especially when you hold the book in your hand and can tell me where the primary source is? If there are “numerous citations”…

    Look…I understand it can become frustrating when a bunch of skeptics invade your blog, poking at every blog entry, pushing back against what you say. (For the umpteenth time, the title, “Tough Questions Answered” does tend to invite it.) And you are to be commended for NOT deleting opposing positions—allowing us to post.

    But do you really think snark is the best approach when a skeptic asks for a citation when you claim “The opposing side says….”? Do you understand the defensive response without giving us a reference only solidifies our suspicion there is no citation? It only confirms it is a strawman argument?

    Your call how you desire to response, of course…

  9. Moreland’s argument is that mental entities exist and you are agreeing with him. Where you are disagreeing, it seems, is whether the existence of mental entities gives any credence to the supernatural. Moreland’s contention in this book is that if there is an immaterial soul (if dualism is correct), then the case for the possibility of life after physical death is strengthened. That seems obviously true to me.

  10. Dagoods,
    With most skeptics, it does not matter how many citations I give, because the skeptic is not after truth – they are merely throwing rocks at whatever target I have erected. If I really believed that you cared to learn about the debate over dualism and physicalism, I would take more time to answer your concerns. But the hostile and accusatory tone of your first comment on this post led me to believe that I would be wasting my time.

    The only other thing I will say is that Moreland is a philosopher, and one of his areas of specialty is philosophy of the mind, so he is a primary source on the subjects of physicalism and dualism. You can be sure that his comments on this topic are scholarly and well-researched. Instead of asking that I provide citations for everything Moreland says, you would be better served thinking about his arguments.

  11. I agree that if a soul existed (defining soul as some kind of nonmaterial part of our being), life after physical death is surely possible. But how are you jumping from these mental entities to a soul?

    When I agree that they exist, this is only in the sense that they have connections to their physical counterparts on which they depend, but are not the exact same thing.

  12. “With most skeptics, it does not matter how many citations I give”

    You only need to give one!

  13. Bill Pratt: …you would be better served thinking about his arguments.

    Again…er…what? I most certainly did think about his arguments. Saw a questionable flaw upon which his argument hanged, and asked for clarification. Look, Moreland’s argument (as I see it) is:

    P1: Physicalists claim X.*
    P2: X is false.
    Conc: Therefore the physicalists claim is false.

    *Everything true of the “brain” is true of the “mind” and vice versa.

    Fairly straightforward. The question is in the first premise–DO Physicalists (or naturalists or materialists) make such a claim? I was looking for a cite where a Physicalist makes such a claim to see precisely what the claim was being made.

    Bill Pratt, you have indicated there are “numerous citations” (albeit without stating there is a citation addressing this particular statement.) You have now expended more time and effort blustering about how the citations exist, how we should go buy the book and look them up ourselves, how we can be sure Moreland is scholarly and well-researched…than it would take to simply give the citations themselves!

    (And no…if Moreland is claiming someone else [physicalists] claim something, he is NEVER a “primary source” because…by definition…he is referring to another source!)

    Bill Pratt: With most skeptics, it does not matter how many citations I give, because the skeptic is not after truth…

    Well…isn’t this ironic! IF (and we cannot confirm this, as you haven’t provided any information) Moreland built a strawperson here by stating Physicalists claim something they do not, then this entire argument is false. I attempted, by asking for a cite, for clarification. If there is no cite, it would seem Morelands first premise is false.

    This entire argument is built on a false claim.

    And I am being accused of not seeking truth…cute.

  14. I realize I’m late getting into this discussion, but I wanted to introduce myself to you, Bill, as someone who has been making the same type of Dualistic arguments against the Physicalist/Materialists for a few years. I state it in an even simpler manner than you do in saying that the existence of a cause and effect relationship between brain chemistry and consciousness (which, I would add, is increasingly recognized as being a two-way street) alone proves that Physicalism is false, since a single entity cannot be both the cause and effect of itself.

    I also like to point out the absurdity of Physicalism’s collapse of all subjectivity into objectivity. It portrays a universe as actually consisting only of objects without any knowing subjects! It is also proven false by recognizing that if we were one day able to observe all of our brain chemistry we would still have to be seen as distinct from this as the observers of the chemistry.

    I have found that people tend to just argue from ignorance at this point in saying that we don’t understand how this works, but it’s possible that we will. At this point I point out the fallacy of hoping for a possible solution to the problem without any possible basis for believing that it can be found, while ignoring the obvious answer: Dualism.

    Alternately, people will sometimes simply accept the self-denial as not being a problem. It’s interesting that the self-denying tendency found here is quite similar to that of Buddhism (especially Zen). Before I became a believer in 1982 I seriously considered becoming a Zen Buddhist. Though I didn’t realize it at the time, I now see that this was due to the anti-theistic presuppositions which I had unwittingly embraced through my public school education. But denial of the reality of our existence and experience simply doesn’t work in practice. After all, even the truly insane have to take it as a given that at least some of their experience is real, otherwise they couldn’t function at all.

    Of course, we know that the reason the type of self-denial found in Buddhism doesn’t work is because God made us as real rational, moral souls housed in real physical bodies. I also tend to press people on the point that they already know their Creator exists, but are naturally-inclined to suppress this knowledge in unrighteousness and to pursue idols (especially, for non-religious types, that their autonomous reason is the ultimate standard and Science as the sole source of knowledge). Though this is from Romans 1:18ff I usually don’t cite this because it’s not necessary. Unlike some Presuppositionalists, I don’t start with the Bible (which people have been strongly brainwashed to dismiss in our Secular age), but with The God of the Bible, Whom they can’t truly dismiss.

    I welcome you to check out some of my apologetic appeals and other articles on my blog: http://christianityistrue.wordpress.com. I am a graduate of Westminster Seminary California, having studied under John Frame, a protégé of Cornelius Van Til. I also do some debating on Twitter under the user name: Duke1CA. Hope this helps.
    Chris Andrus

  15. Chris,
    Thanks for your comments. Your points about the self-defeating nature of physicalism are spot-on. I’ll definitely check out your blog as well.

    God bless,

  16. I appreciate both your comments. I am doing a paper and i believe your back and forth comments helped me understand better then just reading alone.

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