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Mind: Mind-Body Dualism

Are we just physical things? Or perhaps just mental things? Maybe both? In this video, Alex Byrne (MIT) explains a modern argument due to Saul Kripke for mind-body dualism.

Speaker: Dr. Alex Byrne, Professor of Philosophy, MIT.

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  • ohnoes default style avatar for user Tejas
    I feel like Alex simply assumes premise 2 at . He just assumes that you can exist in an incorporeal form or as someone else besides Bert. That to me doesn't have to be true.
    (12 votes)
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  • male robot hal style avatar for user Wudaifu
    Does anyone else notice the clever trick that the speaker attempts to get past us when, at , he displays the question, "COULDN'T YOU HAVE EXISTED WITHOUT BURT EXISTING?", when everything leading up to this question has been about whether or not we are BERT? What I want to know is just who is this BURT fellow and is he or isn't he the same as the BERT we have come to identify with?
    (12 votes)
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  • leaf green style avatar for user Bryce
    I disagree with premise 2. The mind is a property of the brain. If I had a different body, and therefore a different brain, I would also be a different mind. In other words, my mind is physically tied to my brain; I cannot be anyone but myself.
    (11 votes)
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    • piceratops seedling style avatar for user Bashface
      I believe you would operate under different associations not necessarily be a different mind. I mean both are possible, that you could have a different mind and you could have the same mind.

      If you damage your brain then it hinders your mind being able to interact with your brain. You make your statement sound too literal when it should be controversial what you say, not wrong.

      You don't allow for how we literally talk to ourselves in our heads...

      Like a voice in my head or people having voices in their heads. How can you make a voice in your head let alone hear a voice in your head? Like how the guy said just because you call your brain Bert doesn't mean that its Bert, you just call it Bert and it could be Bertha or Sam.
      (0 votes)
  • piceratops ultimate style avatar for user Justin Hsieh
    At , Alex uses Modus Tollens. Isn't that a fallacy?
    (6 votes)
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  • piceratops tree style avatar for user Maria Benitz
    The argument presented in this video fails.

    I have reproduced it here:

    1. If it's true that you are Bert, then it could not have been false that you are Bert.
    2. It could have been false that you are Bert.
    Therefore: It's not true that you are Bert.

    Premise 1 is just self-evident. It's dealing with numerical identity, i.e. you and Bert refer to one and the same object, your physical body. You = Bert = Your Physical Body. So all three terms are interchangeable and any one of them can be substituted for the others. That means we can reconstruct premise 1 and the rest of the argument as follows:

    1. If it's true that you are you, then it could not have been false that you are you.
    2. It could have been false that you are you.
    Therefore: It's not true that you are you.

    In this version, premise 1 is again a self-evident statement about numerical identity. Premise 2 is what makes the argument absurd. Numerical identity is a relationship that is necessarily true. It is not, was not and will never be false that a thing is itself.

    In the original argument, Premise 2 is rather subtle. However, it is self-contradictory just like Premise 2 in my reconstructed version of the argument.
    For the statement 'it could have been false that you are (numerically identical to) Bert' to be true, two things have to be true:
    1. you are (numerically identical to) Bert
    2. fact 1 is contingent (i.e. it could have been false)
    However, numerical identity is by nature a necessary relation, so the premise contradicts itself. A person cannot hold at one and the same time that you are numerically identical to Bert and that it could have been false that you are numerically identical to Bert.
    Premise 2 is clearly false, meaning that this argument is far from sound.
    (4 votes)
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    • orange juice squid orange style avatar for user Daniel Rigal
      This is one of those things like St Anselm's Ontological Argument where you can smell that there is something totally fishy going on but it is slippery enough that you can't quite get a grip on it. The whole thing seems to go from trying to show a tiny possibility that premise 2 is not so totally stupid that it needs to be thrown out on the spot, to accepting it completely and thus the whole thing being proven, which is just silly. It feels like trickery although I am sure that it is not intended to deceive.
      (1 vote)
  • leafers ultimate style avatar for user Brendanhile
    Looking at in the video, which is the summary of the argument; isn't that equivalent to the following situation?
    I have a closed box with a piece of fruit in it (say an Apple, Banana or Orange). I have no data on which piece of fruit it is, so I say:
    Premise 1: If its true that the piece of fruit is an apple, then it could not have been false that the piece of fruit is an apple. (It can't be both an apple and not an apple)
    Premise 2: It could be false that the piece of fruit is an apple. (It could possibly be a banana or orange)
    Conclusion: It is not true that the piece of fruit is an apple.
    This argument is obviously false as the we can repeat it for every member of the set of pieces of fruit that it could be (Apple, Banana and Orange) and come to the conclusion that there is no piece of fruit in the box, which is contrary to the initial conditions. Additionally, we are inferring information about which piece of fruit is in the box, without any information provided.
    Correct me if I'm wrong, but I don't think the argument provided is even valid. Premise 1 is true, the statement "You are Bert" is either true or false - not neither or both. Premise 2 merely states that its possible it can be either- not really providing much information at all. How does that support the conclusion that "You are Bert" is not true? Additionally, couldn't you just invert all the true and false statements in the premises and come to the opposite conclusion?
    (2 votes)
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    • boggle blue style avatar for user Davin V Jones
      Your premises are statements on two different scenarios. The first is a statement about the nature of a piece of apple. The second is about the nature of the potential knowledge of a piece of fruit. To suggest one premise invalidates/contradicts the other is faulty logic.
      (3 votes)
  • piceratops ultimate style avatar for user Anitej Banerjee
    I feel really uneasy having watched this video.
    I don't understand any of it -- not just a specific part. I don't understand either of the 2 premises (which, although a thought experiment were still not justified in anyway), and I don't understand why he said some truths may have been false and some may not. Can someone please explain?
    (3 votes)
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    • leaf orange style avatar for user Randy
      I had a glass of orange juice this morning. If you believe that it was possible for me to have chosen milk instead of orange juice then we have a dichotomy of contingent truths. If however you believe that history is described by the atoms and their dance, then the brain state which produced the decision to have orange juice would produce that same decision when given another chance and there would be no such thing as contingent truths.
      (1 vote)
  • leaf green style avatar for user Eylrid
    The difference between the mind and brain is like the difference between software and hardware. Software requires some form of hardware to exist on, but it doesn't require a specific piece of hardware, per se. For example, I have a program on my hard drive called chrome.exe. Is it possible for chrome.exe to exist without my hard drive? Yes, it could exist on another hard drive, a flash drive, a CD, etc. Could it exist without any physical information storage medium existing at all? No, it has to be stored somewhere.

    The same can be said for a mind. It is theoretically possible for my mind to exist without my brain if it was successfully transferred to another brain, a computer, or some other medium. It is not possible for my mind to exist without any physical medium to exist on. Further, no method has yet been demonstrated for successfully transferring a mind from a brain into another medium, so it is not practically possible at this time for my mind to exist without my brain.
    (2 votes)
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  • male robot hal style avatar for user davis
    A basic concept of arguments is that if it produces a contradiction, it must, somewhere, contain a flaw. How does he use a contradiction to prove something?
    (1 vote)
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    • mr pants teal style avatar for user Robert
      The use of Modus Tollens in this video, (someone may add time tag to help me here), is the prototypical 'proof by contradiction'. The first premise is the implication, P1: "If P, then Q.", itself a very brief argument, one could say, with the single 'premise' P, and the 'conclusion' being Q. The second premise is P2: "-Q". Thus P1 'concludes' with Q, which is false by P2. Our conclusion is that there must be something wrong in the premises of P1, namely P, its only 'premise'. In other words, the conclusion is C: "-P". Hope this helps!
      (3 votes)
  • male robot hal style avatar for user Corey Piper
    At When he says He is him, I'm thinking back to the previous video on the ship of Theseus, specifically the worm theory scenario. Barrack Obama, in fact is a different Barrack Obama. He is not him at different times. But if you look at the lifespan of Barrack Obama, and say all his changes, his growth and decay, are all connected by the temporal dimension of time, then it is true that the this worm of barrack Obama is in fact Barrack Obama.
    (2 votes)
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    • starky ultimate style avatar for user Averatu
      Its a point of being numerically identical, being in the same place and made of the same stuff. A shirt may appear to look identical to another, but in order to be truly identical, it would have to be made of the very same material, with the very same buttons and the very same stitching, and it would have to belong to the same person and hang on the same hanger in the same cupboard, and could then not be owned or worn by 2 different people, because then it is no longer identical, one shirt would have the property of belonging to Bob, and the other the property of belonging to Fred.
      (1 vote)

Video transcript

(intro music) So my name's Alex Byrne. I teach philosophy at MIT, and today I'm going to explain an argument for so-called mind-body dualism, the view that we are not physical or material things. And if we're not physical or material things, the natural alternative is that we're mental things of some kind. Immaterial minds or souls, as it's sometimes put. Hence the term "mind-body dualism." On this view, the universe contains two quite different sorts of things: physical bodies like stones and planets and brains on the one hand, and non-physical minds on the other. Well why is this view important? Well, physical things normally aren't around forever. If I smash my watch into tiny pieces or throw it in a furnace, that's the end of this beautiful piece of Swiss engineering. The watch doesn't exist anymore. Similarly if your body is devoured by worms or consumed in a crematorium, that's the end of this beautiful piece of biological engineering. Your body doesn't exist anymore. So, if you're a physical thing, a complicated bag of cells, then your eventual bodily destruction means that there's no hope for immortality. So, if you're invested in the prospect of life after death, a lot hangs on the argument for mind-body dualism. The seventeenth-century philosopher Rene Descartes is the most famous proponent of mind-body dualism, and that's why the view is sometimes called "Cartesian dualism." You'll remember Cartesian coordinates from high school geometry, and Descartes invented those. His most famous work is called "Meditations on First Philosophy," which was published in Latin in 1641. And the sub-title promises that the work will demonstrate the existence of God and the immortality of the soul. We can only do so much in a few minutes, so we'll have to leave the demonstration of the existence of God for another episode of Wi-Phi. Now the argument I'm going to present is not quite Descartes's argument as we find it in the Meditations. It's basically a variant of Descartes's argument, given by the contemporary philosopher Saul Kripke in his classic book "Naming a Necessity," which was published in 1980. And what's more, it's a simplified version of Kripke's argument. But even with the simplifications, I think we can see that it certainly leads to an argument that deserves to be taken seriously. All right, so now to the argument. Let's give your physical body a name. Call it "Bert." Everyone, dualist or not, can agree you and Bert are intimately connected. Stamp on Bert's toe, and you feel pain. If you decide to get some aspirin, that will result in Bert moving towards the medicine cabinet. However, that doesn't mean that you are Bert. And according to the dualist, you aren't. There are two things here: you and Bert. And what the dualist argument tries to establish is that you are not Bert. More explicitly, you are not identical to Bert. You are not one in the same thing as Bert. Okay, so that's the conclusion. So now, to prepare for the premises of the argument, we need a distinction, between truths that could have been false and truths that could not have been false. For example, here's a truth: I am a philosopher. That truth could have been false. I could have been a plumber, say. Plumbing might have struck me as a more fulfilling and secure career than philosophy, and I might have studied for a plumbing certificate instead of studying for a PhD in philosophy. Here's another example: it's true that there were dinosaurs. But that could have been false. Evolution could have failed to produce any dinosaurs, or life might not have evolved at all. So some truths, then, could have been false. But some truths could not have been false. They had to be true, come what may. For example, here's a logical truth: either there were dinosaurs, or there were no dinosaurs. That's true, but it didn't just happen to be true. It couldn't have been otherwise. However the world turned out, that logical truth would have been true. Here's another example, which is the relevant one for our purposes. Imagine that the President of the United States, say, is sitting opposite us. I point to him and say, "He is Barack Obama." That's true. But could it have been false? Well, how could it? How could that very man fail to be Barack Obama? We have just one thing here: that man, also known as "Barack Obama." When I say "He is Barack Obama," I'm picking out the same thing twice over. It's as if I were to say "He," pointing at Obama, "is him," pointing at Obama again. A thing can't fail to be identical to itself. So "He," here I point at Obama, "can't fail to be identical to Obama." So, when I say "He is Obama," what I say is not just true, it had to be true. It's one of those truths like that logical truth I just mentioned. It could not have been false. If you're inclined to doubt this, you're probably thinking of some different, but related, truth that could have been false. For example, it's also true that he, pointing at Obama, is named "Barack Obama." But that's a truth that could have been false. He might have had some, different name say Fred Blogs. But the truth that he is Barack Obama is not the same as the truth he's named Barack Obama. The first truth is not about language, although of course it is stated in language, like truths in general. It's just about the man, Barack Obama. The second truth is about language, at least in part. Specifically, it's about the name "Barack Obama." And of course these are quite different things. Barack Obama is the president, but his name has not been elected to any office. All right, now we're ready for the argument. Go back to you and Bert, your body. Imagine I point to you and say "You are Bert." Suppose that's true. Then, since it's just like the Obama example, it's one of those truths that could not have been false. In other words, if it's true that you are Bert, it had to be true that you were Bert. You are Bert, come what may. So this gives us the first premise of our argument for dualism. If it's true that you are Bert, then it could not have been false that you are Bert. But hold on. Couldn't you have existed without Bert existing? For example, you can imagine being disembodied, not having a body at all or you can imagine that you have another body, Bertha, not Bert. Imagining these situations is not at all like imagining, or trying to imagine, say, a situation in which there's a round square table. That situation seems obviously impossible, not a situation that could have obtained. There could not have been a round square table. But there seems nothing at all impossible about a situation in which you exist without Burt existing, perhaps because you're disembodied, perhaps because you have Bertha and not Bert as your body. This is not the actual situation, but it seems like a possible situation. You could have existed without Bert existing. But if you could have existed without Bert existing, then it could have been false that you are Bert. A situation in which you're around and Bert isn't is a situation in which you aren't Bert. So this gives us our second premise, "it could have been false that you are Bert." So now notice that the second premise is the negation of the sentence after the word "then," in the first premise. So our two premises have the following abstract form: "If P, then Q; and not Q." And premises of this form logically imply, by a rule of inference called "modus tollens," "not P." And our two plausible seeming premises, then, imply "it's not true that you are Bert." In other words, you are not Bert, which is the dualist conclusion. Subtitles by the Amara.org community