Sunday, May 11, 2014

Plantinga's Modal Argument for the Immateriality of the Mind

This argument is consistent with substance dualism, hylemorphism, and a host of other philosophical views that hold that the mind is an immaterial substance.

1. There is a possible world at which my mind exists apart from my body. (Premise)

2. Whatever is possible is necessarily possible, e.g. possible in all possible worlds. (Premise, S5)

3. Hence, my mind possibly exists apart from my body in the actual world. (From 1 and 2)

4. Therefore, my mind is distinct from my body. (Implied by 3)

A skeptic's best bet to avoid the conclusion that the mind is immaterial is to reject premise (1).  However, one would be hard-pressed to find any inconsistency in the conception of the mind existing apart from the body.  Premise (2) is based on the relatively uncontroversial S5 axiom of modal logic, and (3) simply follows from (1) and (2).  (4) is implied by (3) because unless two things - A and B - are distinct, then A cannot exist apart from B.  Therefore, unless the mind is actually distinct from the body, then it would not be possible for the mind to exist apart from the body, which contradicts (1).


  1. The first premise shoud read 'there is a possible world in which minds exist apart from bodies'. To say that it is possible for MY mind to exist from MY body is question-begging.

    Moreover, this is based on the concept of "immaterial substances", a concept so ill-defined that nobody can rationally decide whether it is possible or not. If we analyze the concept we get something like "something that is nothing", which is downright contradictory.

    In short: this is a non-argument.

  2. Can you find any contradiction with the notion of the mind existing apart from the body?

    And, it's perfectly acceptable to define something by negation. If a material thing is a thing extended in space, then an immaterial thing is something not extended in space. That's a pretty unambiguous definition.

  3. I have no idea what "things not extended in space" could possibly mean other than absolutely nothing. So I cannot find a contradiction in the notion of "fwdrrykjhn" existing apart from the body, because I haven't got the slightest idea what "fwdrrykjhn" means. But I am sure you agree that saying that there is a possible world in which "fwdrrykjhn" exists is conpletely unjustified. At this stage it would also be unjustified to say that there is no possible world in which "fwdrrykjhn" exists.

    Moreover, you skipped my first objection. MY mind can either exist apart from MY body or it can't. Supposing you also imply that for MY to exist apart from MY body if it is immaterial (and not some seperable material part of my body), then My mind is either material or immaterial. But if MY mind is material it cannot be immaterial, since it would not be MY mind.

    The argument, as it is now, is clearly question-begging.

    Now, I apologize for the capital letters, but it's the only way I can emphasize certain words. I'd prefer italics or bold but I have no idea how to do that.

    1. Walter, as you now know, I have a personal policy of not debating non-cognitivists. If "extended in space" is meaningful, then so is its negation. So unless you can come up with a better objection that, I'm afraid we're done on this point.

      Secondly, I didn't skip your first objection. I asked if you could find some contradiction in the notion that the mind exists apart from the body. "It is logically impossible for the mind to exist apart from the body" is a much stronger claim than premise (1), so you have a much more significant burden of proof.

      As for italics, all you have to do is write a word or phrase between the following two:

    2. If "a pocket with red marbles" is meaning ful then "no pocket with no marbles" is indeed meaningful, so if you deny "extended in space" and still claim something is left you have the burden to show what exactly is left. Until you do there is nothing to debate.

      As for my first objection, what you are saying here has nothing to do with it, so instead of skipping it , you just completely misunderstood it.

      But never mind, I this argument is too unimpressive for me to spend any more time on it. So, we'll have to agree to disagree.

      I would like to know, though, how to do italics, because in your post , after "all you have to do is write a word or phrase between the following two:" there is nothing (or maybe there really is something that is not extended in space).

    3. That's weird the characters didn't show up. They look like this: < i > < / i >, only without the spaces, and you enter the text between each set of characters.

    4. As you know, I'm a Thomist. I argue for God's attributes using apophatic (negative) theology. We do not know God's essence, which entails we don't define His attributes the way we would our own. That's been part of classical theology for millennia. Defining things by negation is indeed meaningful, as your own example illustrates. I don't have to explain what's left; otherwise I'd be using cataphatic (positive) theology, which is contrary to Thomism. Saying there's nothing to debate is just hand-waving.

      Now, if you think I misunderstood your first objection, you could try clarifying it instead of calling the argument "unimpressive." The argument has a long history of well-respected proponents, of which I named Plantinga in particular.

  4. I think materialists can avoid this by simply embracing functionalism rather than identity theory. With functionalism, the mind is not identical to the brain and therefore there is no contradiction in conceiving of a mind without a brain.

    1. Hi Martin, one could adopt functionalism, but I think that would result in a trivial objection. As Putnam, Searle, and others have pointed out, functionalism either reduces to behavorism or to panpsychism (the latter due to the internal structures of functionalism potentially being present everywhere).

    2. Doug, this is true, but my point was that these identity arguments for dualism only get one so far, and that by themselves cannot be taken to be arguments for dualism. That the case for dualism must be built further upon that foundation, I think

    3. Martin, I ask for your patience here. What further foundation are you referring to?

    4. I keep forgetting about your blog, here! Sorry!

      Other arguments for dualism. The modal arguments like this that prove the mind is not identical to the brain are all well and good, but it may leave you with functionalism. And then you ought to argue against functionalism and eliminativism to move beyond materialism and actually into dualism. My point is that this modal argument can only take you as far as functionalism all by itself.