Is it possible for two things to be exactly alike in every way? Or is every pair of objects different in some way, no matter how subtle? I discuss the history of this question, along with contemporary objections.
It seems the counter-examples using electrons, blacks balls, and so forth do not succeed in providing a negation or falsification of the identify of indiscernibles. The reason being that the explanation of the existence of any object must also be taken into account. If two things have the exact same explanation then on what grounds could you call them two and not one? If, for example you'd say that they are different because of some reason X, then, you've succeeded in finding a difference and thus self-refuting.
Actually, upon further contemplating this, simply by stating that there are two things (no matter how many attributes they share) you've successfully made a distinction and thus refuted your own argument or are not taking the principle head on but only an understanding (straw-man-like) that isn't truly refuting the identity of indiscernibles. Hand-waving away that a difference in location is not sufficient to make a distinction fails, it seems, because by that distinction it is that a distinction is made. That is taking away that which differentiates simply to maintain the point.
I have an objection in 8:05 - Once the paint bucket appears, it already differentiates the two spheres because one has a bucket closer to its location than the other sphere.
Thanks for making a cool video about this. I'm a 30 year old philosophy major looking back at some of my favorite concepts learned in school. I learned this one in my history of modern philosophy class.
What about an object having temporal parts, can't this solve the problem? For example, if I pour the red paint on one of the spheres in the counterexample, and the paint does not appear on the other sphere, then I could claim that they were never the same sphere, since they do not share the same temporal parts. Has none thought of this response among philosophers? Would be surprised if they haven't. Btw great videos! you should pick up making videos again!
Ik im 6yrs late, but i have a problem with Wiggins reduction. We know that libnz principle states that:" no two things can be alike in every aspect". In wiggins 3rd premise he states that according to the libnz principle the two spheres are identical, but at the same time libnz principle says that no two things are alike. Either i misunderstood the definition of libnz law or wiggins did.
Here’s something entirely more respectable, without all the priming, dazzle -dazzle, and that not only specifies assumptions, doesn’t have any mention of his etc. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-WldDrN-5ujg.html
Leibniz states that no two objects are completely indiscernible from each other. And that to suppose that there are is to suppose that both are the same thing, called by different names. And this is true since two objects positioned in different places already differentiate themselves because both are subject to different actions and experiences, and such actions and experiences already draw a distinction between the two. This is why there's an identity of indiscernible. The assumption presented in the video is false, not because Leibniz got it wrong, but because it is the example that Leibniz uses to confront Clarke in the Correspondence.
Thank you very much for this! It helped me greatly with my university presentation. Do you by any chance have the reference to David Wiggins' argument? (i.e thesis etc.)
Hi, it seems that you are not aware of the principle of indistinguishability of quantum mechanics. According to modern science two electrons A and B which interact are "entangled", i.e. are described as one and only one thing, and there is no way to distinguish electron A from B afterwards. Moreover, Hawthorne hypothesis of "bilocated particular" and the (apparent) "action at a distance" is precisely what is observed experimentally in the micro-world and that puzzzled so much Einstein and all physicists until today. If the property of one electron is changed it "spills" to the other electron too, even if they are light years away, just as in the example of the red paint. Even Wiggin's argument as a reductio ad absurdum is falsified by QM: there the disorder of a subsystem is more than that of the system as a whole (i.e, the entropy of a subsystem is larger than that of the whole system). Extending the analogy to the iron single sphere: one half of it has no longer the same properties than the other once you separate it from the whole sphere. So, I think the Leibinz's principle not only holds but is even confirmed by many experiments of modern physics against our macroscopic view and conception of reality.
***** Thanks for your comment. :-) Yes, I am aware that some people, citing quantum mechanics, treat the aforementioned arguments as theorems rather than reductios. If contemporary science says that quantum entanglement allows for action at a distance, then of course we should permit its possibility. Unfortunately, quantum entanglement is the sort of thing that only applies to tiny, particle-sized quanta. So the objection to macroscopic bilocated particulars, such as iron spheres, still applies. The dissimilarity of a system's entropy to that of its subsystems, while interesting, does not require any such dissimilarity between two equal subsystems. You may be interested in the following paper from the journal "Mind," which discusses these issues in excruciating detail: philsci-archive.pitt.edu/9898/1/RiseRelationals-July2013.pdf. (See especially pp. 20-22, although the discussion is spread throughout.) Once again, thanks for watching!
Dr. Bowers' Office Hours I'm not sure physicists would agree with Muller's statement that "fermions and bosons alike are weakly discernible" when entangled. As I understand it, just eq.33 states the contrary. Probably I should go through all the bunch of papers to understand what he really means... Anyhow, the quantum indiscernibility in macroscopic objects breaks down due to quantum mechanical decoherence effects (so called "collapse of the wavefunction", etc.) which are characteristic for objects of many particles and at non absolute zero temperature. That is, while at a microscopic level two objects with exactly the same properties are allowed, and therefore must be describe as one and the same thing, in the macrocosm they are not. The idea of the two identical spheres or droplets with exactly the same features is only a mental idealization that can't be realized in the physical reality, even not in principle, just because microscopically QM breaks down indistinguishability a priori. So, in the humanly observable universe no two objects will never have the same properties. Not so in QM. Therefore, there is no contradiction and PII is saved. :)
***** Thanks again for the helpful commentary! :-) Note that, to show that the PII is false, one only needs show that, logically, it is possible for two objects to exist with exactly the same features. The key word here is "logically," as opposed to "physically." Historically speaking, defenders of PII have taken it to be a logically necessary truth--one which must hold, in other words, at all logically possible worlds, i.e. worlds, whose only requirement is that no contradictions are true in them. If what you say is correct, then no universe, which obeys the same quantum mechanical laws as our own, can have two exactly similar objects. However, not all logically possible universes share our quantum mechanical laws. It seems logically possible, for instance, to have a universe with completely different laws of nature from our own. It seems logically possible to have a universe with different kinds forces, or different kinds of particles, which could only be described using loose analogies with our own. It seems logically possible to have a universe, which is very much like our own, save for the fact that the temperature is at a perfect zero degrees kelvin. It seems logically possible to have a universe, whose physics is exhausted by the generalizations one might make about the behavior of objects in Looney Tunes shorts. There is no logical contradiction in describing such universes. You might label these universes as "only a mental idealization," but as long as one can describe and imagine them without any contradictions, this is strong evidence for their logical possibility. Now, in stating your objection to PII's apparent counterexamples, you used the qualifying phrase, "humanly observable universe." This is important. My point here is that not all logically possible universes are also humanly observable ones. Perhaps you disagree. Perhaps you think that every logically possible universe must also share our laws of nature. However, that is a very controversial claim about the nature of modality--one that, for various reasons, is a minority position among professional philosophers. As such, it requires a further argument. Some contemporary philosophers have offered such further arguments. See "Causality and Properties," by Syndey Shoemaker, for instance, or the work of either Alexander Bird or Brian Ellis. If you are passionate about this topic, you may find them quite enjoyable! Either way, thanks again! :-)
Dr. Bowers' Office Hours Hi Dr. Brower, thanks for the suggestion to look after Shoemaker's book. Will take a look if I find it in the library. I'm not sure to understand your argument... I have no problems to accept the eventuality of the existence of "multiverses". Indeed, it is a theory quite in fashion among many cosmologists nowadays since it would explain several aspects of the laws of physics of our universe (among others the fine tuning of the fundamental constants for the emergence of life). So, let us assume other universes with different physical laws exist. For me this could be only a reason more to think that there can not exist another object identical with one in our universe. The objects in a universe with laws different than ours must be even more distinguishable from ALL the objects in our universe. Because, I can't see how two objects could have the same properties if they are governed by different natural laws, since the physical properties are themselves dictated by the very same laws. For me it amounts to a physical and also logical circular self-contradiction. This is where I couldn't follow... Whereas, if you mean that, two objects with exactly the same properties are allowed to exist in another universe different than ours, since they might not be governed by the laws of QM which causes macroscopic objects in our universe to be necessarily all different from each others, then we can't conclude so straightforwardly that this shows PII is false. We would have to proof then that, if such two objects exist, they are not the same object (for example by coloring one red and see what happens to the other, etc.). You might claim this is absurd nonsense which is a logical impossibility. But we perceive it so nonsensical only because our minds and sensorial perceptions are tuned to a macroscopic world whereas, as I explained before, if we would live in a microscopic world governed by the laws of QM we would, on the contrary, accept this as normal commonsense. So, if other universes exists with one ore more identical objects in it, then there is the burden of proof: PII has to be falsified. We have first to find out for another universe, peek at it the two identical objects and make some experiment that confirms or denies PII. But then, first of all it is not entirely clear if this is possible, even in principle. You yourself say they are humanly not observable and many would describe this eventuality as mere metaphysics that has no longer to do neither with science nor with logic (in fact this is also a controversy that surrounds the multiverse theory). But even if... well... I'm afraid we will have to wait still a very long time to see this experiment to happen. :) That's why, until then PII can not be ruled out. Even not logically.
***** Thanks again! I am enjoying our conversation. :-) Just to clarify, Shoemaker's piece is an article, not a book. It's printed in an Oxford Studies in Philosophy anthology, entitled "Properties," edited by Mellor and Oliver. It's a good anthology, full of some famous, and also very interesting, papers. On the subject of many, equally existing universes, see David Lewis' canonical text, "On The Plurality of Worlds." (It's a really awesome book! I highly recommend it. :-) ) You may find that the sense, in which philosophers like Lewis accept the existence of many universes, is quite different from the "many worlds" interpretation of QM. You are correct that, when we raise the possibility of two exactly similar spheres in a world with different laws, we should ask whether we are really imagining a bilocated particular. (Indeed, this is the question raised by Hawthorne, in his article, which I reference in the video.) I do not think bilocated particulars are *logically* impossible; indeed, it seems we can clearly, coherently imagine them. So they are possible. However, we can *also* clearly, coherently imagine two exactly similar spheres; those are also conceivable. There is no contradiction in the idea. So they, too, are possible. You are correct that there is no way to physically experiment on the contents of these other worlds, which we imagine. But we do not need to perform physical experiments on something, simply to see whether it can be conceived without a contradiction. On the contrary. If we can clearly imagine something, and if we can give a coherent, thorough description of it, that is evidence that it is possible. To show that such a thing is *not* possible, one would have to show that there is some contradiction in the idea. But it does not seem that we can. (You can see why it is hard to argue for PII: in doing so, one has to argue that exactly similar objects are not even coherently conceivable. That's quite a tall order!) (Note that, if we had to physically experiment on something to establish that it is possible, then we would have to conclude that the only possible things are things that actually exist, since the only things we can experiment on are things that actually exist. But that is surely wrong. Surely, some things are possible, even though they are not actual. I am not blue-eyed, for instance, and I never was, nor will I be. But I could have been. How do we *know* that I could have been? Well, not by physical experiment. Rather, we know because we can clearly imagine it, and describe it without any contradictions. That's how most philosophers reason about possibility these days, anyway.) Once again, thanks for your commentary! ~Dr. Bowers
So you simply assert that two locations in space (not points since Aristotle proved space is not composed of indivisibles) are identical. This is begging the question.
