Dualism is true.

I am proposing that dualism about the mind - that the mind and the body are ontologically distinct as my opponent kindly pointed out for the readers - is true, and because I sense that this may turn into a lengthy and detailed debate, I am only going to be using one argument for dualism. This argument has always been intended as a metaphysical demonstration of the truth of dualism, so if the premises are sound, the conclusion is established with certainty. If sound that would entail that the philosophy of the mind my opponent holds to is false. Almost all forms of the argument, modern and ancient, have their roots in the famous philosopher Rene Descartes. [1] This argument has several names but I will be calling it the modal argument because I like the name better. ;) -------------------------- The Modal Argument -------------------------- As a preliminary, let me state a very important principle that these types of arguments for dualism rely on that is usually only implied and not explicitly stated. This ontological principle is called "Leibniz's Law" which states "the identity of indiscernibles. What this means, roughly, is that if there is no conceivable way of telling the difference between A and B, then A is B. More precisely, A is B if, and only if, all the attributes of A are also attributes of B (and vice versa). To put it yet another way, A is B if everything which is true of A is also true of B (and vice versa again). " [2] This principle is relatively uncontroversial in metaphysics, but it's uses are usually contested. Yet, it has important implications in philosophy of the mind - if the mind has attributes or properties that the body does not then have then it cannot be identical to the body, or more specifically, the brain. Let me explain - claims of identity are necessary, if and only if, they involve "rigid designators" on both sides of the equation. A rigid designator "designates the same object in all possible worlds in which that object exists and never designates anything else. " [3] This is a term coined by the philosopher Saul Kripke. Interestingly, this leads to many seemingly counter-intuitive ideas such as the fact there are posteriori necessary truths; it has been generally thought that a posteriori truths are contingent. This means that there are necessary truths that are found through experience. An example of this would be water = H20. If water is the same thing as H20 as we know it is, it follows that water = H20 in every possible world it exists as well. What does this mean? That it's inconceivable to think that water is not H20. Thus, it should be inconceivable for me or anyone else to conceive of the mind as being distinct from the body if it is the same thing. Surely this not the case and the mind has an attribute or property that the body does not have, namely the ability to be conceived of disembodied. Obviously, a body cannot be conceived of (nor imagined) as disembodied. So, by Leibniz's Law, the mind is ontologically distinct from and not identical to the body. 1. It is imaginable that one's mind might exist without one's body. therefore 2. It is conceivable that one's mind might exist without one's body. therefore 3. It is possible one's mind might exist without one's body. therefore 4. One's mind is a different entity from one's body. [4] A relatively simple argument, that if sound, establishes an important conclusion. I will now move on to defending each premise. ------------------------- Premise 1. "It is imaginable that one's mind might exist without one's body. " ------------------------- I believe this is relatively uncontroversial. Surely one can imagine having an out of body experience like hovering over and looking down on one's body at a murder scene. Or one could imagine being like an insubstantial ghost with no body going through wall buildings. ------------------------- Premise 2. "Therefore, it is conceivable that one's mind might exist without one's body. " ------------------------- I believe this is also relatively uncontroversial. Imaginability is forming a mental image of something. Conceiving of something (in this context) is thinking of something without logical contradiction. Not all things that are conceivable are imaginable - I can conceive of shape with 1,000,000 sides (in that there is no logical contradiction) but not imagine it - but all things that are imaginable are conceivable. So, if it is imaginable that minds exist without bodies then it is conceivable. -------------------------- Premise 3. "Therefore, it is possible one's mind might exist without one's body. " -------------------------- This is not relatively uncontroversial. It is very controversial. The question is from P2 does P3 follow? Or does conceivability entail metaphysical possibility? Well, the greatest skeptic (hehe) of them all, David Hume, certainly thought so: "Tis an establish'd maxim in metaphysics, That whatever the mind clearly conceives includes the idea of possible existence, or in other words, that nothing we imagine is absolutely impossible. We can form the idea of a golden mountain, and from thence conclude that such a mountain may actually exist. We can form no idea of a mountain without a valley, and therefore regard it as impossible. " [5] As to not make an argument from authority I merely bring that quote up to say that that conceivability entails possibility has generally been accepted up until modern times. Of course, that doesn't mean it's right by virtue of the fact of general consensus of past philosophers but I think the principle is right. The objector can object that it's possible to conceive of a something that is metaphysically impossible therefore refuting the principle that conceivability entails metaphysical possibility. Opponents of this argument sometimes will even bring the water = H20 example that I mentioned earlier against this principle. They suggest that it is possible to conceive of water (with all the same attributes) being a different chemical composition than H20, something like B3Z, even though they agree in the actual world it is necessarily the case that water = H20. So then we'd have a case of conceivability not entailing metaphysical possibility and the argument would fail. This example would be wrong, though. I can appeal to Kripke's notion of rigid designators here. "Water" would designate the substance in the actual world that has properties of being a liquid, freezing and turning to gas at a specific temperature, etc. "H20" would designate the substance in the actual world that has a specific chemical makeup. So H20 in any possible world would designate what whatever substance that has a specific chemical makeup. If we know that the substance with the properties of being a liquid (etc) is the same as the substance with a specific chemical makeup in the actual world then water = H20, so water and H20 must be the same in ever metaphysically possible world. It is therefore inconceivable and thereby not possible that water =/= H20. If we said we had a substance that had all the properties of water but it has a chemical makeup of B3Z it would not be water as there is no such substance in the actual world. Now one of the major objections to the principle that conceivability entails metaphysical possibility is rendered ineffective, and furthermore, if you carefully consider the notion of rigid designators and properly apply them then are an no legitimate objections to be made. Besides, how would objectors know that anything is metaphysically possible without using conceivability? -------------------------- Conclusion "Therefore, one's mind is a different entity from one's body. " -------------------------- This conclusion follows if the above argument is sound.