- #106
moving finger
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It may be clear and straightforward, but is it necessary? I could claim that we need a 7-valued logic (7 is my lucky number), but simply claiming it does not make it necessary (in the sense of being a necessary assumption to enable our understanding of the world). This seems to me like an expression of Heisenberg’s personal beliefs, but this doesn’t make such a belief necessary. Heisenberg (it seems) simply could not accept the notion of the excluded middle, therefore he chose to reject this premise. That’s an assumption of his. But does this make the assumption necessary? How could we tell?In quantum theory this law ‘tertium non datur’ is to be modified. Against any modification of this fundamental principle one can of course at once argue that the principle is assumed in common language and that we have to speak at least about our eventual modification of logic in the natural language. Therefore, it would be a self-contradiction to describe in natural language a logical scheme that does not apply to natural language."
Canute said:This seems clear and straightforward to me, but is there an objection I'm unaware of?
Could you give an example where this “Heisenberg-modified tertium non datur” can be applied?
Why do you say it contradicts reason? Please show that this follows. You are assuming first of all that the universe has “arisen” - presumably in time – which then assumes that time exists outside of the universe. Why can it not be the case that the universe has existed for all time (be careful how you define time)?Canute said:To see what he means here consider any metaphysical question. Take the something/nothing question of cosmogony for example. It contradicts reason that the universe arises from something or nothing.
Not until you answer the question above. A meaningless question does not have a yes/no answer, but this does not mean we have rejected the law of the excluded middle.Canute said:In other words, this question is undecidable in ordinary logic.
Saying that “the universe arose” already presumes some backdrop of time against which it arose – what if time is an intrinsic part of the “creation” of the universe? If there is no background “time” before the “arising” then there can be background “time” against which the “arising” occurs (this should appeal to a mystical mind). One can expect yes/no answers only if one poses meaningful questions.Canute said:The cause of the problem, according to Brown (and me) is that the universe did not arise from something or nothing. Rather, this distinction is ultimately innapropriate when considering such ontological questions.
It rather seems like a neat way of avoiding the question!Canute said:Would this not be a rather neat explanation of why metaphysical questions are undecidable?
The whole reason why the possibility of a “third way” arises in quantum mechanics is precisely the same as the reason it arises in conventional logic – some questions are meaningless. To ask “is the King of France bald?” is a meaningless question, it has no true or false answer, because the object it refers to (the King of France) does not exist. In the same way to ask “what is the position and momentum of this quantum object” is also a meaningless question, it has no unique answer because the position and momentum of a quantum object cannot be simultaneously precisely specified (the concept of simultaneous position and momentum does not exist in QM).
Thus in both QM and logic there do indeed exist “true”, “false” and “meaningless” propositions, but there is no need to invoke a fourth class of “imaginary” propositions. This latter is imho simply mystical nonsense.
If you disagree, perhaps you could provide an example of a proposition which you believe is neither true, false nor meaningless, but is instead “imaginary”?
Agreed – but this does not prevent us from measuring one property at a time (or assigning a probability to one property at a time).selfAdjoint said:The properties of position and momentum are complementary. This means they cannot be measured at the same time.
If you pin down the position of something accurately, then the momentum becomes completely uncertain, but this is not the same as saying “it doesn’t exist as a measurable property”. I can choose to measure whatever I wish, but quantum mechanically I cannot measure both position and momentum simultaneously.selfAdjoint said:If you pin down the position of something accurately, the momentum becomes completely undefined It doesn't have a probability distribution; it just doesn't exist as a measurable property.
Paul – I know that I cannot change your mind, and I am not here for that reason. I am here simply to explore the limits of my own understanding of the world, to find out through test and experiment and discussion whether my beliefs are rational, coherent and sound, and to learn for myself whether I need to change any of those beliefs.Paul Martin said:Well, if you don't think my ideas are nonsensical, then I don't think you will change my mind.
All I can do is to show you the water – it is your decision as to whether you drink from it or not. Changing your mind is under your control, not mine. (It’s like the old joke about “how many psychiatrists does it take to change a lightbulb?” – answer : “None – the lightbulb must want to change by itself”)
I’m a great believer in the saying “one can lead a horse to water, but one cannot make him drink”. Your PC is inherently complex – it thinks, it knows, it understands, it perceives, it makes decisions, it is conscious, it has intentions and desires, and it seems to me that you feel you need to assume such properties as “a priori properties of the world” because you do not believe these properties could arise solely from complexity if they were not already somehow “built-in” to the boundary conditions. If you genuinely believe that the assumption of this primordial PC is a “simple assumption” then you and I are talking a fundamentally different language. (It’s similar to the theist idea that the assumption of God is a simple assumption).Paul Martin said:As for complexity, I don't think my ideas are any more complex than yours. In fact, I don't think our views of cosmogony and cosmology are very far apart after all.
My “solution” to the problem is that I reject the conventional mathematician’s dogma that an integer is a number generated by adding 1 to itself a “finite” number of times. Why does the conventional mathematician insist upon “finite”? To me, an integer is a number which is generated by adding 1 to itself an arbitrary (unlimited) number of times, and in the limit “unlimited” tends to infinity. Thus we arrive at the concept of an infinite integer, and thus no problem generating an infinite set of integers. I don’t see how the mathematics of integers can be claimed to be consistent otherwise. And incidentally the whole of Cantor’s ideas about different levels of infinity thereby goes out the window – the cardinality of the integers is just the same as the cardinality of the reals as soon as we acknowledge the existence of infinite integers (the only reason Cantor was able to show allegedly different levels of infinity was because of the incoherent notion of an infinite cardinality of finite integers).Paul Martin said:In my view, you have to account for the existence of an infinite number of integers if you are going to depend on the infinite set in any of your arguments. The Axiom of Infinity (which according to Wikipedia seems to be included in ZF theory) allows for the definition and thus existence of the infinite set. But I have the same problem that you seem to have in that the mere acceptance of the axiom doesn't explain "how one can generate an infinite set of integers (ie a set with infinite cardinality) using this procedure."
See below. Your evidence for the alleged contradictions inherent in the concept of an infinite set (the set of all logical possibilities for example) was Russell’s paradox. I have shown (and continue to explain below) that Russell’s paradox has nothing to do with infinity, it has to do with self-referentiality, and the paradox occurs even in finite sets.moving finger said:Russell’s paradox is not a consequence of infinity, it is a consequence of unrestrained self-referentiality. THIS is why I said that legislating against infinity does not make the problem go away.
Paul Martin said:We may disagree here. I think the consequences of accepting infinity are fatal. I'm not sure about self-referentiality (Long ago when I read GEB I thought so, but now I'm not so sure. I need to take that course in Foundations.)
Pardon me, but it seems to me that you are avoiding the question. Yes of course one (whether “one” is the PC or a human agent) must choose axioms (how many times in how many threads have I said that we must make assumptions before we can arrive at any explanation or understanding of the world?) – and one is of course free to choose those axioms. But given the choice of axioms, the laws of mathematics then necessarily follow. Take again my example of Pythagoras’ theorem – given Euclid’s 5 postulates (axioms) then the theorem necessarily follows – neither the PC nor any human (given the assumptions) has any freedom at all to change this.Paul Martin said:The PC could still express whims and wishes in the choice of logic to use and then in the choice of primitives and axioms. (PC might choose ZF or maybe ZFC or some other.) The laws of mathematics follow from these arbitrary choices. I think the analogy of chess applies exactly here.
Humans are in exactly the same position. We can choose axioms, and the laws of mathematics follow from these axioms. There is nothing “special” about the PC in this respect – the PC is thus as powerful and as powerless as any human agent.
Of course. But the PC has no more “power” to choose the laws of mathematics than do humans. We humans choose the axioms, then we deduce the laws which follow. How is the PC any different to this?Paul Martin said:The laws of mathematics are contingent on the logic system chosen and on the primitives and axioms chosen.
Can you give an example of a choice that the PC could have made which a human is not capable of making?Paul Martin said:PC could have chosen a different logic system, and within that system, PC could have chosen from among many different sets of primitives and axioms. Many (but of course not infinitely many) different mathematical systems are possible.
The issue here is that the question depends on the context. To ask “is the quantum entity a particle?” is a meaningless question outside of the context of a measurement. All propositions can be reduced to either true, false or meaningless.Canute said:The proposition: 'A quantum entity is a wave' is neither true nor false. Likewise, 'A quantum entity is a particle' is neither true nor false. 'A quantum entity is neither a wave nor a particle' is neither true nor false and so on. I mentioned the background-dependence problem because physicists seem to be reaching the same sort of conclusion about the fundamentality of spacetime. Some have proposed the hypothesis of duality as a solution, by which spacetime is fundamental or not depending on how we look at it. So the proposition 'spacetime is fundamental' would be neither true nor false.
I’m not sure if I’m sorry or happyPaul Martin said:This comment had me lying awake early this morning.
Artificially restricting the universe to 2 and only 2 classes is OK, and in this case it eliminates the concept of the additional third class of all classes that are not members of themselves, but this is hardly a realistic scenario, and it does not follow from this that the general solution in a universe with a finite number of classes avoids Russell’s paradox. If I have N classes (where N is a finite integer), I can always construct another class (numbered N+1) which is the class of all classes (selected from the original N classes plus the new N+1 class) which are not members of themselves. I still have a finite (N+1) number of classes, but I now also have Russell’s paradox – and no sign of infinity.Paul Martin said:Suppose the universe consisted of exactly 2 classes, say A and B. Then how could one define 'the class of all classes'? Since we are using the term 'class' in the phrase, to be consistent, we must mean the same thing by the term as we mean in the premise. In other words, the class of all classes must be a class. And since the universe consists of exactly two classes, A and B, the class of all classes must be either A or B. There are no other candidates. If the class of all classes is A, then it does not include B which is inconsistent with any reasonable meaning of 'all'. Similarly if it is B.
If we define 'the class of all classes' to be the class {A,B} then we are inconsistent with the premise because we now have a third class which is neither A nor B.
Think of it in terms of the Barber’s paradox – this is another variant. In Seville there is a barber who shaves everyone who does not shave himself. Now ask – does the barber shave himself? Clearly at anyone time there are a finite number of individuals in Seville – thus the paradox has nothing to do with either infinity or time.
The barber paradox is EXACTLY of the same form as Russell’s paradox of the class of all classes that are not members of themselves – and the paradox arises because of self-referentiality.
Nope – the problem is in self-referentiality. The “class of all classes that are not members of themselves” is class N+1, but it refers not only to all of the original classes N but also to ITSELF (class N+1). This has nothing to do with infinity, or with time. It has only to do with self-referentiality. This is precisely why Russell tried to get rid of the problem by eliminating self-referentiality through partitioning sets and classes – so that a class (ie the set N+1) could refer to a set (ie any of the sets N), but was not allowed to refer to itself (ie the set N+1). Infinity has absolutely nothing to do with it. Neither does time.Paul Martin said:I think the problem is in the notion of "all". I think a consistent notion of "all" of anything must be time dependent. We must qualify 'all' by specifying "all at a point in time".
Paradox is inherent in self-referential systems – I think there is a warning there for our understanding of consciousness (which is also ultimately a self-referential system).
It need not be connected with time (don’t forget that I don’t believe “the body of mathematics grows” in an ontic sense – all that grows is human knowledge of mathematics – the epistemic sense). You may see the paradox as a temporal progression, whereas I see it as a logical progression. Standing “outside of time” one can see the same atemporal paradox. The barber who shaves all those who do not shave themselves obviously has to shave one person at a time, but the paradox is not a time-dependent paradox – the barber may choose to decide whether he shaves himself or not before he decides whether to shave anyone else.Paul Martin said:The problem is that the body of mathematics grows. What may be a proposition or a conjecture at one time becomes a theorem later as a proof is discovered. Similarly, if we consider a finite case, such as the existence of only A and B as above, we may introduce new concepts at a point in time which extend the "universe". So, if we have only A and B, and we form a new set with A and B as its members, we have extended the universe and from that point of time onward, 'all' has a new and different meaning.
What you have done is exactly what Russell did in his theory of types – he said that set C is in a different class to sets A and B, therefore set C cannot (= is not allowed to) refer to itself – thus eliminating the paradox.Paul Martin said:Let's look at it in a different way. What does it mean for a set to be a member of itself? Well, let's look at an example.
Let A = {A,B}. The definition of A is recursive, but is it consistent? And does it make sense? Logically, it seems to me that there is no reason we can't define 'A' this way.
Now let's say the universe consists of exactly, and nothing but, the sets A and B and the set, C, which is defined as the set of all sets that are not members of themselves. At the time we define 'C', the only set which is not a member of itself is B. So at the time we define 'C' we have C = {B}. Then, and only after we have defined 'C', can we ask the question, "Is C a member of itself?" The answer is clearly "no" in this example.
I don't think this presents a contradiction or a difficulty. You might say that since C is a set and since C does not contain itself as a member, it must belong to the set of all sets that do not contain themselves as members. But I would say that you don't get a chance to refine, or redefine, your definitions as new concepts are added to your mathematical system. You have already defined 'C' once. That definition is consistent and you are not at liberty to change it later.
Imagine that C is the barber, and A and B are two residents of Seville. A shaves himself, but B does not. Now we say that the barber (C) shaves all those that do not shave themselves – thus C shaves B. By your “rule” we are not allowed to ask if C shaves himself (thus avoiding the paradox) – and this is just what Russell tried to legislate against. But it has nothing to do with either time or infinity – it has to do with self-referentiality. Basically what you are saying is “we are not allowed to ask whether C shaves C – that is not a legitimate question”.
Indeed, I can reduce the set to 1. Imagine all the residents of Seville have left town, except for the barber. Once again, the barber shaves all those who do not shave themselves. But now there is only one person left in town to be shaved – the barber himself. We have a unique set, a single set. And we still have the paradox. Conclusion : Russell’s paradox has nothing whatsoever to do with infinity. It has to do with self-referentiality.
Time is a red-herring (as time usually is – it is indeed strange how time figures in many false human intuitions). The issue is purely one of logical self-referentiality. In practice the barber could shave himself before he shaves anyone else – but you would still claim that the question “does the barber shave himself?” (ie “does C shave C?”) is a question which is not allowed.Paul Martin said:As I see it, the only problem presented is the interpretation of the word 'all' without considering the time-effectiveness of the concept. If I agreed to give you all the money in my checking account, I would reserve the right to specify exactly when the balance was going to be calculated.
Thus having rejected the idea that "Russell’s paradox is a contradiction entailed only by notions of infinite sets", we get back again to the question of why you think the notion of an infinite set involves contradiction. Over to you.
Best Regards
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