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A quasi-cartesian argument for the immateriality of the intellect

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  • A quasi-cartesian argument for the immateriality of the intellect

    Hello everyone!

    I thought about an argument for the immateriality of the intellect, which seems more or less like the one that Descartes gave based on the indubitability of the mind. I don't see clear-cut objections, so I would like to share it with you, to see if you can find "good" flaws.

    Here it is, in a not-so-much-inspired syllogistic form:

    1. The existence of an intellect can be known with objective certainty.
    2. The existence of a material part of a body can't be known with objective certainty.
    3. If A=B, then A has the same properties as B.

    4. An intellect and a material part of the body doesn't have the same properties. (By (1) and (2).)

    5. Therefore, an intellect isn't a material part of a body.

    (1) can be defended on the ground that if you wanted to show that intellect isn't known with objective certainty, you'll need to engage in thinking. But to do so is to presuppose that an intellect exist. The activity of thinking is the testimony to its own existence: when we understand that, we see why we can't escape the conclusion that an intellect exist. So, we can know its existence with certainty.
    I would argue that (2) is true on the basis that we know the material parts of bodies with perception. But can we coherently deny the existence of what we perceive with our senses? It seems so.
    (3) seems self-evident.


    Maybe the first reaction would be "It's the masked-man fallacy." But I'm not sure it's the case. Let's say:

    1. Lois Lane doesn't believe that Clark Kent can fly.
    2. Lois Lane believe that Superman can fly.

    3. Therefore, Superman isn't Clark Kent.

    But my argument isn't like this one. It would rather be:

    1. Clark Kent has the property of being believable to don't have the capacity to fly.
    2. Superman has the property of being believable to have the capacity to fly.
    3. Clark Kent is Superman.

    4. Therefore, ???

    We can see why they aren't analogous with my argument.

    What could be the others objections?
    • Could we say that some of our perceptions are infaillible? But how? Why it isn't already the case for the others? And if they can be, can they be when we focus on bodies?
    • Can material parts of bodies be known on abilities other than perception? But which? Maybe God have the ability to do that. But would it help the materialist? God is somethink like an immaterial intellect. It would be hard to stay materialist on ourself despite this.
    • Deny the indiscernibility of identicals. Ok, but on what basis? If it's on the behalf of the conclusion, that's question-begging.
    • "It doesn't proof that we are/have an immaterial substance." True. But it show at least that some real operation isn't material.
    • "Your notion of thinking is incoherent!" I'm not sure what to say.

    If you see obvious refutations, or if you know about the exact name of this type of argument in the litterature, feel free to share your thougts.
    Last edited by Ouros; 03-11-2019, 12:09 PM.

  • #2
    I think you're on to something. However, I would reject 2 or at least I have my doubts about it. I think one can, by means of rationale, prove the objectivity of a part of ones body. Although, its going to involve a certain set of defeasible assumptions.

    The basic thrust of the argument would be something like, rejecting the reliability of your senses is incoherent, therefore, the existence of a part of your body is certain (because you've sensed a part of your body)

    P1 All knowledge starts with sense experience
    P2 In order for one to coherently reject the reliability of ones senses, one must have reliable knowledge
    P3 However, if one has unreliable senses, the knowledge that follows from that is unreliable
    P4 Therefore, it is incoherent to deny the reliability of ones senses

    The assumption that all knowledge starts with sense experience may be unfounded, especially from a rationalist point of view, however, I would argue that even when making arguments from pure reason, one must have had reliable sense experience in order to derive logical axioms to work off of. Although, I am willing to hear other ideas, but it seems to me to be the simplest, most plausible theory.

    Also, I think you could leave out 1 and 2 all together. If you could defend 4 on its own merit, the argument would still follow. Perhaps, by showing how the capacity to obtain abstract objacts isn't a material feature, the qualitative-quantitave difference between the two, etc

    Comment


    • #3
      Originally posted by Ouros View Post
      Maybe the first reaction would be "It's the masked-man fallacy." But I'm not sure it's the case. Let's say:

      1. Lois Lane doesn't believe that Clark Kent can fly.
      2. Lois Lane believe that Superman can fly.

      3. Therefore, Superman isn't Clark Kent.

      But my argument isn't like this one. It would rather be:

      1. Clark Kent has the property of being believable to don't have the capacity to fly.
      2. Superman has the property of being believable to have the capacity to fly.
      3. Clark Kent is Superman.

      4. Therefore, ???

      We can see why they aren't analogous with my argument.
      Since you accidentally inserted a "don't" in (1) I am not certain what you meant to claim is the proper analog of your argument. But anyway I'm worried that this reply is not open to you.

      Say the materialist grants that the intellect is known whenever one does any thinking. You recognize that there are two ways of talking about this knowledge, one where intellect enters into the intensional content of what is known, the other where intellect is simply what is known, an object to which we could assign a property of being known.

      It's right that the first option will not help the argument. For if the intellect were a material thing, then in might be that a subject knows "My intellect exists" without knowing "That material thing exists," even if it were true that his intellect were that material thing.

      But I think there's a similar problem with the second option. I'm guessing you meant to exclude the "don't", and the point was that even though Lois Lane doesn't believe that Clark Kent can fly, there is a property being believable to have the capacity to fly that holds of objects however they are described. Superman has that property, and Clark Kent is Superman, so Clark Kent has that property. But then the materialist is free to say that the same is the case with the intellect. There is a material thing which is known to exist whenever one does any thinking: the intellect.

      If you did mean to include some negating particle in (1), then Clark Kent and Superman turn out to have different properties, which is impossible given your third premise, unless the statements that they have these properties throw us back into the fire of intensionality.

      Originally posted by Ouros View Post
      What could be the others objections?
      • Could we say that some of our perceptions are infaillible? But how? Why it isn't already the case for the others? And if they can be, can they be when we focus on bodies?
      • Can material parts of bodies be known on abilities other than perception? But which? Maybe God have the ability to do that. But would it help the materialist? God is somethink like an immaterial intellect. It would be hard to stay materialist on ourself despite this.
      • Deny the indiscernibility of identicals. Ok, but on what basis? If it's on the behalf of the conclusion, that's question-begging.
      • "It doesn't proof that we are/have an immaterial substance." True. But it show at least that some real operation isn't material.
      • "Your notion of thinking is incoherent!" I'm not sure what to say.

      If you see obvious refutations, or if you know about the exact name of this type of argument in the litterature, feel free to share your thougts.
      As a matter of presentation, is there a special reason for your use of the term objective certainty?

      On the face of it, people can be certain about the existence of their body parts, and they can be correct as well as justified. That, at least, is how we will see things if we do not think that external world skepticism will carry the day.

      Sure, I am sometimes wrong in beliefs formed on the basis of perception. It wants argument that, on that basis, I should be less than certain about beliefs formed on the basis of perception in general.

      Comment


      • #4
        Originally posted by ClassicalLiberal.Theist View Post
        I think you're on to something. However, I would reject 2 or at least I have my doubts about it. I think one can, by means of rationale, prove the objectivity of a part of ones body. Although, its going to involve a certain set of defeasible assumptions.

        The basic thrust of the argument would be something like, rejecting the reliability of your senses is incoherent, therefore, the existence of a part of your body is certain (because you've sensed a part of your body)

        P1 All knowledge starts with sense experience
        P2 In order for one to coherently reject the reliability of ones senses, one must have reliable knowledge
        P3 However, if one has unreliable senses, the knowledge that follows from that is unreliable
        P4 Therefore, it is incoherent to deny the reliability of ones senses

        The assumption that all knowledge starts with sense experience may be unfounded, especially from a rationalist point of view, however, I would argue that even when making arguments from pure reason, one must have had reliable sense experience in order to derive logical axioms to work off of. Although, I am willing to hear other ideas, but it seems to me to be the simplest, most plausible theory.

        Also, I think you could leave out 1 and 2 all together. If you could defend 4 on its own merit, the argument would still follow. Perhaps, by showing how the capacity to obtain abstract objacts isn't a material feature, the qualitative-quantitave difference between the two, etc
        As you say it yourself, some rationalist could defend the falseness of P1. I'm not sure either that P3 is true. I would say it depends on what you mean by P1. We may need sense experience first in a temporal way, but not in the "chain of justifications." If that was the case, the line beetween a priori and a posteriori would be blurried.
        Anyway, I think we can accept both P4 and my argument, because my argument isn't that perception isn't reliable, but that it's uncertain. Incidentally, you say yourself that your argument involve defeasible assumptions.


        Originally posted by Greg View Post
        Since you accidentally inserted a "don't" in (1) I am not certain what you meant to claim is the proper analog of your argument. But anyway I'm worried that this reply is not open to you.

        Say the materialist grants that the intellect is known whenever one does any thinking. You recognize that there are two ways of talking about this knowledge, one where intellect enters into the intensional content of what is known, the other where intellect is simply what is known, an object to which we could assign a property of being known.

        It's right that the first option will not help the argument. For if the intellect were a material thing, then in might be that a subject knows "My intellect exists" without knowing "That material thing exists," even if it were true that his intellect were that material thing.

        But I think there's a similar problem with the second option. I'm guessing you meant to exclude the "don't", and the point was that even though Lois Lane doesn't believe that Clark Kent can fly, there is a property being believable to have the capacity to fly that holds of objects however they are described. Superman has that property, and Clark Kent is Superman, so Clark Kent has that property. But then the materialist is free to say that the same is the case with the intellect. There is a material thing which is known to exist whenever one does any thinking: the intellect.

        If you did mean to include some negating particle in (1), then Clark Kent and Superman turn out to have different properties, which is impossible given your third premise, unless the statements that they have these properties throw us back into the fire of intensionality.
        Actually, I did mean to include negating particle. Sorry if I wasn't clear.
        Now, I don't think that it imply that Clark Kent and Superman have different properties. Both/he has the properties "being believable to don't have the capacity to fly." and "being believable to have the capacity to fly." Maybe you think that's incoherent? But that's just to say that Lois Lane believe contradictory thing, so it isn't. (Well, I also think that my formulation of those properties is pretty poor. I hope you understood what I meant by that.)

        That said, your first objection is still there even in that case.
        First, I insist on the fact that's it's not about mere knowledge in the case of the intellect, but certainty.
        Second, we should be careful to distinguish "being known" and "being knowable." An object can both be known, and not known, like in a "masked-man context". But being knowable and not knowable is incoherent. That's why I would say that the cases aren't analogous: the intellect can be known with objective certainty, the body can't be known with absolute certainty, even less the identity "a material part of a body=an intellect".

        [EDIT] I think I need to explain with more details. The materialist may again object "But we can known with absolute certainty the existence of the material part of a body! Because the mind IS a material part of the body." But it's problematic.
        One, it seems question-begging. Well, one man's modus ponens is another man's modus tollens I suppose...
        Two, it doesn't help because it supposes he also know with absolute certainty the identity "a material part of a body=an intellect"! But it's the same problem as before: the materialist would still need perception to know this with certainty, and perception is faillible.

        Originally posted by Greg View Post

        As a matter of presentation, is there a special reason for your use of the term objective certainty?

        On the face of it, people can be certain about the existence of their body parts, and they can be correct as well as justified. That, at least, is how we will see things if we do not think that external world skepticism will carry the day.

        Sure, I am sometimes wrong in beliefs formed on the basis of perception. It wants argument that, on that basis, I should be less than certain about beliefs formed on the basis of perception in general.
        To distinguish it with subjective certainty.
        Subjective certainty would be the mere psychological impossibility to give up some belief. Objective certainty is the epistemic impossibility to give up the belief, or something like that. A proposition who the mere belief in its truth imply its truth would be one which is objectively certain.

        That's also why I say that perception can't give us objective certainty. As you say, we can be wrong when we belief proposition based on perception.

        (I'm not saying that we can't be justified on the basis of perception, nor not knowing something. However, we can't be certain.)
        Last edited by Ouros; 03-11-2019, 05:16 PM.

        Comment


        • #5
          Originally posted by Ouros View Post
          Actually, I did mean to include negating particle. Sorry if I wasn't clear.
          Now, I don't think that it imply that Clark Kent and Superman have different properties. Both/he has the properties "being believable to don't have the capacity to fly." and "being believable to have the capacity to fly." Maybe you think that's incoherent? But that's just to say that Lois Lane believe contradictory thing, so it isn't. (Well, I also think that my formulation of those properties is pretty poor. I hope you understood what I meant by that.)

          That said, your first objection is still there even in that case.
          First, I insist on the fact that's it's not about mere knowledge in the case of the intellect, but certainty.
          Second, we should be careful to distinguish "being known" and "being knowable." An object can both be known, and not known, like in a "masked-man context". But being knowable and not knowable is incoherent. That's why I would say that the cases aren't analogous: the intellect can be known with objective certainty, the body can't be known with absolute certainty, even less the identity "a material part of a body=an intellect".
          I see. I was thinking it was an error because in English you wouldn't use "don't" in the infinitival context but rather "not". Let me see whether I can restate your point to see whether I have got it.

          These are consistent:
          (1) Lois Lane believes that Clark Kent does not have the capacity to fly.
          (2) Lois Lane believes that Superman has the capacity to fly.

          And we might think that, unlike "A believes that _ has the capacity to fly", the context "_ is believed to have the capacity to fly" is extensional. If so, then these are also consistent:
          (3) Clark Kent could be believed to have the capacity to fly.
          (4) Clark Kent could be believed not to have the capacity to fly.
          (5) Superman could be believed to have the capacity to fly.
          (6) Superman could be believed not to have the capacity to fly.
          Or are these not acceptable reconstructions of the properties you have in mind?

          But your idea is that these are not consistent:
          (7) The intellect is knowable-with-objective-certainty.
          (8) The intellect is not knowable-with-objective-certainty.
          These are not analogous to the Superman examples because the negating particle falls outside the scope of what is known, for which reason they are contradictories. If the materialist admits (7) and is committed to (8), then he is in trouble.

          You are arguing that the materialist is committed to (8), because
          (9) The body is not knowable-with-objective-certainty.
          And you claim (9) is true because
          (10) The material part of a body is not knowable-with-objective-certainty
          which is true because
          (11) The material part of a body is known only through perception.

          Again, my suggestion was that the materialist, if he doesn't reject (7), can deny commitment to (8). He will say that on his view, the intellect is a material part of the body (or something similar). So if the intellect is knowable-with-objective-certainty, and "_ is knowable-with-objective-certainty" is an extensional context as your argument presupposes, then a material part of the body is knowable-with-objective-certainty. You reply to this:
          Originally posted by Ouros View Post
          The materialist may again object "But we can known with absolute certainty the existence of the material part of a body! Because the mind IS a material part of the body." But it's problematic.
          One, it seems question-begging. Well, one man's modus ponens is another man's modus tollens I suppose...
          Two, it doesn't help because it supposes he also know with absolute certainty the identity "a material part of a body=an intellect"! But it's the same problem as before: the materialist would still need perception to know this with certainty, and perception is faillible.
          I would say first of all that the materialist does not need to know with absolute certainty that "the intellect is a material part of a body". He would only be committed to that if what had to be known-with-objective-certainty is something which implies "the material part of a body exists". But that is only the case if we give "_ is knowable-with-objective-certainty" an intensional reading, in which case (9) does not imply (8).

          His point is that if your conclusion is to deny this identity, then you cannot presuppose its falsity in arguing against him. If it's true, then in knowing-with-objective-certainty the intellect, a subject knows-with-objective-certainty a part of his body. (9)-(11) are false.

          As he might put it, the intellect is not only knowable-with-objective-certainty, but also knowable-without-objective-certainty. That is not a contradiction, and it is intelligible if the intellect could be known in multiple ways.

          Tu quoque, the materialist might suggest that you're committed to that anyway. For how do you know other people's intellects? Not with objective certainty. That an intellect might be known without objective certainty, on the basis of perception, seems to be possible. So why not in one's own case?
          Last edited by Greg; 03-11-2019, 08:50 PM.

          Comment


          • #6
            You perfectly understand what I meant in the first part. Again, sorry if I wasn't clear the first time.

            Originally posted by Greg View Post
            I would say first of all that the materialist does not need to know with absolute certainty that "the intellect is a material part of a body". He would only be committed to that if what had to be known-with-objective-certainty is something which implies "the material part of a body exists". But that is only the case if we give "_ is knowable-with-objective-certainty" an intensional reading, in which case (9) does not imply (8).

            His point is that if your conclusion is to deny this identity, then you cannot presuppose its falsity in arguing against him. If it's true, then in knowing-with-objective-certainty the intellect, a subject knows-with-objective-certainty a part of his body. (9)-(11) are false.
            I think I get what you say, but there's still something that's bothering me.

            Let's take those three propositions:

            (I) An intellect is knowable-with-objective-certainty.
            (II) A material part of a body is knowable-with-objective-certainty.
            (III) The intellect is a material part of a body.

            I would say that every proposition of the form "X is knowable-with-objective-certainty" is also knowable-with-objective-certainty. I don't understand how we could say that the epistemic justification of an epistemic justification of a proposition and this epistemic justification of a proposition are different. (By epistemic justification, I mean the scale with something like "Unknown" on one side, "Objectively certain" one the other. So, the "knowability" of a proposition is the part of epistemic justification it can have.) For example, (I) is knowable-with-objective-certainty, per the same reasoning.

            Now, a materialist can argue that he can show (II) is true with the help of (III).
            Still, here's a problem: if what I say above is correct, then he also need to show that (II) is knowable-with-objective-certainty. But if I don't talk nonsense, in a syllogism, the epistemic justification of the conclusion is as strong as the weakest of the premises. So, it would mean that the materialist should show that (III) IS, in fact, knowable-with-absolute-certainty.

            Does it make sense? I think it bypass the intentional context you were objecting to. (Honnestly, I'm a little tired right now. I may have make mistakes. It's my last message tonight, I will read your eventual answer tomorrow.)

            Comment


            • #7
              Originally posted by Ouros View Post
              You perfectly understand what I meant in the first part. Again, sorry if I wasn't clear the first time.
              No problem at all.

              Originally posted by Ouros View Post
              Let's take those three propositions:

              (I) An intellect is knowable-with-objective-certainty.
              (II) A material part of a body is knowable-with-objective-certainty.
              (III) The intellect is a material part of a body.

              I would say that every proposition of the form "X is knowable-with-objective-certainty" is also knowable-with-objective-certainty. I don't understand how we could say that the epistemic justification of an epistemic justification of a proposition and this epistemic justification of a proposition are different. (By epistemic justification, I mean the scale with something like "Unknown" on one side, "Objectively certain" one the other. So, the "knowability" of a proposition is the part of epistemic justification it can have.) For example, (I) is knowable-with-objective-certainty, per the same reasoning.
              I agree you'll be fine if the bolded claim is true. Perhaps you can rephrase your argument for it.

              It is hard to me to assess without knowing what sort of things you'll grant are knowable-with-objective-certainty.

              A consequence of that principle is that if something is knowable-with-objective-certainty, then it is so under every description true of it. It seems as though there should be counterexamples to such a claim. For instance, presumably a subject knows his thoughts with objective certainty. But another thing true of any particular one of his thoughts is that it occurred at such-and-such a time. So it can be described not just (like any thought) in terms of its content but also as the thought which so-and-so had at such-and-such a time. It can be known under the latter description, but not with objective certainty, because it can only be so known by someone who knows the time, which seems to be related to perception, and about which people can be wrong.

              Comment


              • #8
                Originally posted by Greg View Post
                I agree you'll be fine if the bolded claim is true. Perhaps you can rephrase your argument for it.

                It is hard to me to assess without knowing what sort of things you'll grant are knowable-with-objective-certainty.

                A consequence of that principle is that if something is knowable-with-objective-certainty, then it is so under every description true of it. It seems as though there should be counterexamples to such a claim. For instance, presumably a subject knows his thoughts with objective-certainty. But another thing true of any particular one of his thoughts is that it occurred at such-and-such a time. So it can be described not just (like any thought) in terms of its content but also as the thought which so-and-so had at such-and-such a time. It can be known under the latter description, but not with objective certainty, because it can only be so known by someone who knows the time, which seems to be related to perception, and about which people can be wrong.
                Let's be honnest here: I can't find a good response to your objection.

                I thought about possibles answers, but none seems sustainable. So, except if I realize that one of them is succesful, I think I'm pretty much obligated to say that the argument isn't sound after all.

                Now, there's something interesting in the example you took. It seems that what someone can know about a thought with certainty is its content. That said, the link between the content of a thought and when the thought happens seems contingent. Even if the content was about time, the thought itself could happened in a different time that the one the subject is thinking about.
                But that's not the type of link that the materialist would like to be in the case of matter and mind, I think. Maybe there's a similar argument to the one I gave who can make this distinction and make it works, but I'm not sure at all.

                Comment


                • #9
                  Originally posted by Ouros View Post
                  Let's be honnest here: I can't find a good response to your objection.

                  I thought about possibles answers, but none seems sustainable. So, except if I realize that one of them is succesful, I think I'm pretty much obligated to say that the argument isn't sound after all.
                  Sometimes that happens in philosophy!

                  But also there may be, as you suggest, similar arguments that can be made to work.

                  Comment


                  • #10
                    Yeah, I also share Greg's doubts with this kind of argument. Which is a shame. I really would like to find a Cartesian-esque argument that works, especially since full-blooded rationalism is a very admirable philosophy, but I haven't had much luck yet.

                    But there's a different kind of argument against materialism and non-reductive materialism. Rasmussen's countability argument. I suggest you check it out, it's pretty interesting.

                    Comment


                    • #11
                      Originally posted by Atno View Post
                      Yeah, I also share Greg's doubts with this kind of argument. Which is a shame. I really would like to find a Cartesian-esque argument that works, especially since full-blooded rationalism is a very admirable philosophy, but I haven't had much luck yet.

                      But there's a different kind of argument against materialism and non-reductive materialism. Rasmussen's countability argument. I suggest you check it out, it's pretty interesting.
                      Could you link his argument?

                      Comment


                      • #12
                        I didn't have much time to think about a modified version which works, but it would be interesting to know if the little I thought of is already problematic.

                        Just as I said to Greg, the fact that the counter-example is one where the identity beetween two properties of the same thing is contingent. Namely, beetween the content of a thought, or so it seems, and the time when this thought happened.
                        Now, my idea would be to simply restrict the argument to when different aspects are necessary. Is it arbitrary/ad hoc? I don't think so, even if I may not be able to conclusively prove it right now. It seems pretty intuitive to see why, when an identity is contingent, a possibility of mistake appears.

                        If you accept that, here's what I propose:
                        1. If necessarily X is Y, then the existence of X can be known with as much certainty as the existence of Y.
                        2. The existence of a material part of a body can't be known with as much certainty as the existence of an intellect.
                        3. If materialism is true, then necessarily an intellect is a material part of a body.
                        4. Therefore, it isn't necessarily that an intellect is a material part of a body.
                        5. Therefore, materialism is false.
                        I can't, yet, or maybe never, give a good defense of (1). We could give some "conceivability criteria" reason, or maybe an induction from known cases (like the knowability of the existence of the morning star compared to the evening star), but that's too much weak to convince anyone.
                        Reason for (2) are basically the same on that I have told before: both the identity "An intellect is a material part of a body" and "A material part of a body" seems to require perception, which is faillible.

                        Now, it wouldn't be intelligent from my part to reflect too much about this argument if there's some obvious problem with it that I can't see. So... if anyone, again, have a good objection, I would be interrested to hear what you have to said.



                        Originally posted by ClassicalLiberal.Theist View Post

                        Could you link his argument?

                        I think he's talking about this one: https://www.researchgate.net/publica...ve_Physicalism

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