Zeno's Paradoxes

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  • #36
Originally posted by ahrkron
What I'm saying is that Zeno's arguments also apply to your theory, in which motion is just a projection within the Mind.
Misunderstood you. Sorry.
However now that I understand your point, I have to disagree with it anyway. For Zeno's arguments are irrelevant to a Mind-reality. Such a reality is a physical-singularity. Motion doesn't really occur. And since Zeno's paradox seems to question the actuality of motion, my hypothesis fits in nicely with this challenge to real-motion. The motion of an observer, within his own mind (full of sensations), is the motion of the mind itself... within itself. It is a shift of perception which yields the appearance of motion - within the mind. The mind doesn't really cross lengths. It changes its perspective of that length, thus yielding the perception of motion. But the mind moves nowhere. Only sensations are changed.
 
  • #37
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Alright, I'd say that that particular paradox is pretty well covered. My thanks to everyone, especially those who explained it using math. I got up to basic Calculus, so I got the meaning out of the equations (possibly easier than I would have gotten it, if someone had tried to explain it in words - rather, it was much more solid/believable, when seen from a mathematical stand-point).

For some reason, I can't think of another of Zeno's paradoxes, at the present moment. I'll try and think of another one - I know I had some in mind, when I posted the thread. If anyone else can think of one to discuss, I'd be happy to discuss that one also.
 
  • #38
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Originally posted by Lifegazer
Yes... you've shown that it converges towards '1'. But you didn't explain why '1' is ever reached. That's why I asked at what point does "Distance=L/2+L/4+L/8+..." converge to 'L'?

The link I gave you explains how the series converges. As for "at what point" does it converge, I don't know what you mean.

"The length is singular. And the time to traverse it is also singular. It's not really surprising to see that '1' is at the heart of the debate. Zeno may have implied that the time to traverse a given length would be infinite. But what he means here is that the time to traverse a given-length cannot become singular in itself.

What do you mean by the last sentence? I know what Zeno meant, and it has nothing to do with 'singular', it has to do with 'infinite' (as in: "It will take an infinite amount of time to cross any distance").

I.e., that the oneness (completeness) of time to traverse a given singular-length cannot be achieved. [added note: basically, what he's saying is that it would take an eternity to achieve completeness/singularity of the given-length, if travelling in a manner which mirrors "L/2+L/4+L/8+...".]

What is "oneness(completeness) of time"? What is "completeness/singularity of the given-length"?

I think he was really arguing (or he should have been arguing) that the time to traverse a given length can never become complete - and that therefore, time does not converge to a singular value. I.e., does not converge to '1' (which is the symbol of completeness, in this case)."
If it takes an eternity to converge towards '1', then '1' is not grasped.

Sure, that is what he was arguing. Basically it goes like this:

1. If it takes an eternity to traverse a distance L, then that distance cannot be traversed.
2. It takes an eternity to traverse a distance L.
3. Therefore, that distance cannot be traversed.

But Premise 2 is false.

It is Zeno's use of language which is the issue. His 'paradox' can equally be applied to the eternal-convergence of singularity.

No, it is not his use of language. It is his mathematical error which is the issue.

I have no doubts that present-day mathematics are more advanced than in Zeno's day. But that's not the issue. The issue is whether those mathematics are conceptual, or whether they also reflect a tangible-reality (to which they are being applied). I think the issue is one of reason, rather than of mathematics.

It is an issue of mathematics because that is how Zeno defined the problem from the start. Just read any account of the paradox, and you will see it.
 
  • #40
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Originally posted by Tom
Oooh, I t'ought you'd neva ask.

http://plato.stanford.edu/entries/paradox-zeno

I'd never heard of the "Plurality Paradox". It seems like utter nonsense to me (no offense to anyone who agrees with Zeno on this).

Would anyone like to try and defend it?
 
  • #41
Originally posted by Tom
The link I gave you explains how the series converges. As for "at what point" does it converge, I don't know what you mean.
I'm not a mathematician, as you know. I was hoping you'd give a narrative of those math and explain what they say, in language. And I know we've spoken about it last year. But I honestly can't remember what your explanation was. But I do remember that I saw a problem with the tangibility of those math. I.e., I doubted that they could be applied to a tangible-reality (with real motion). This might not be important to you, but whether reality is 'tangible' (as opposed to conceptual... mind-ful) is the underlying issue raised by Zeno's paradox. And so I consider such a question to be worthy of discussion.

You say that Zeno was wrong because he dealt with the divergence of a series, as opposed to the convergence of a series. But the same 'paradox' exists with both possibilities. So it's not even relevant that he should make this error. The question still remains:-
How does "Distance=L/2+L/4+L/8+..." , converge to 'L'?
Or; how can there be an eternal progression towards '1', whereby '1' is finally yielded? Does this signify the end of eternity? Paradox abounds and Wuli should be all over you like a rash, at any minute.
What do you mean by the last sentence? I know what Zeno meant, and it has nothing to do with 'singular', it has to do with 'infinite' (as in: "It will take an infinite amount of time to cross any distance").
Again, it's not really relevant as to whether we deal with a diverging-series, or a converging-series. But you don't seem to grasp that "It will take an infinite amount of time to cross any distance"; can also be stated thus: It will take an eternity to converge towards any point (singularity). Or; it will take an eternity to converge towards '1'.
Zeno isn't really saying anything which contradicts a convergence towards '1'. I think he's been misread.
Sure, that is what he was arguing. Basically it goes like this:

1. If it takes an eternity to traverse a distance L, then that distance cannot be traversed.
2. It takes an eternity to traverse a distance L.
3. Therefore, that distance cannot be traversed.

But Premise 2 is false.
Given "Distance=L/2+L/4+L/8+..." , is a series that goes on forever, I do not see how a such a series can come to a convergence (an end) at 'L' (or '1'). If it comes to an end, then that series is not going-on forever. So how does mathematics overcome this problem?
It is an issue of mathematics because that is how Zeno defined the problem from the start. Just read any account of the paradox, and you will see it.
It is actually a discussion about concepts (motion; length; time.). Any mathematics which deals with these concepts, must obviously conform to the reasoning which distinguishes between 'tangible' and 'conceptual'. Because, if mathematicians trust the reason which has formulated math, then mathematicians should also take notice of any reason which makes those aforementioned distinctions.
Any philosophy which seeks to discredit Zeno, cannot do so merely with mathematics. For Zeno does not ask how mathematics manages to converge towards '1', conceptually. Zeno asks how tangible-things can achieve such events. And so, an argument of reason is required to discredit Zeno. Mathematics, when dealing with concepts such as 'infinity', has to take-note of the fact that 'infinity' is an intangible-concept.
 
  • #42
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Originally posted by Lifegazer
I'm not a mathematician, as you know. I was hoping you'd give a narrative of those math and explain what they say, in language.

I don't expect you to be a mathematician. That's why I presented a link that uses only high school math. I can't explain how to sum a series "in language".

But I do remember that I saw a problem with the tangibility of those math. I.e., I doubted that they could be applied to a tangible-reality (with real motion). This might not be important to you, but whether reality is 'tangible' (as opposed to conceptual... mind-ful) is the underlying issue raised by Zeno's paradox. And so I consider such a question to be worthy of discussion.

You still don't get it: Zeno is the one who brought the math into it. Any problems you have with the 'tangibility' of math, and you'll have to take it up with Zeno. I'm only telling you why he's wrong.

You say that Zeno was wrong because he dealt with the divergence of a series, as opposed to the convergence of a series. But the same 'paradox' exists with both possibilities. So it's not even relevant that he should make this error.

I don't know what you're thinking, but the paradox disappears completely if you correct the mistake.

The question still remains:-
How does "Distance=L/2+L/4+L/8+..." , converge to 'L'?

As I said, the link explains it. Ask me again, and I'll tell ya the same.

Originally posted by Lifegazer
Again, it's not really relevant as to whether we deal with a diverging-series, or a converging-series.

Of course it is--Zeno relies on the divergence of the series to say what you are about to say...

But you don't seem to grasp that "It will take an infinite amount of time to cross any distance"; can also be stated thus: It will take an eternity to converge towards any point (singularity). Or; it will take an eternity to converge towards '1'.

...and of course, it won't take an eternity. The series I gave you is the time that it will take.

Zeno isn't really saying anything which contradicts a convergence towards '1'. I think he's been misread.

Certainly by you, it seems, because the infinite series is part of the problem, and he gets it wrong.

Given "Distance=L/2+L/4+L/8+..." , is a series that goes on forever, I do not see how a such a series can come to a convergence (an end) at 'L' (or '1'). If it comes to an end, then that series is not going-on forever. So how does mathematics overcome this problem?

It does converge, and the link explains why.

It is actually a discussion about concepts (motion; length; time.). Any mathematics which deals with these concepts, must obviously conform to the reasoning which distinguishes between 'tangible' and 'conceptual'. Because, if mathematicians trust the reason which has formulated math, then mathematicians should also take notice of any reason which makes those aforementioned distinctions.

No--really--it is a discussion about mathematics. Just read the paradox on any one of a zillion webpages.

Any philosophy which seeks to discredit Zeno, cannot do so merely with mathematics.

Of course it can, because Zeno brought it into the arena of mathematics. Again, just read the paradox.

For Zeno does not ask how mathematics manages to converge towards '1', conceptually.

Of course he doesn't ask how the series converges--He asserts that it diverges. Again, just read the paradox.

You've obviously got some studying to do on this issue. Read the paradox, see where Zeno puts the infinite series into it, and see where he gets it wrong. It's not that difficult.
 
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  • #43
Originally posted by Tom
...and of course, it won't take an eternity. The series I gave you is the time that it will take.
Does L/2 + L/4 + L/8 + L/16 + L/32... ad-infinitum... converge to 'L'?
And if the above series is considered to be infinite, then how can it ever stop at 'L'?

An infinite-convergence (towards 'L' or '1') cannot stop - simply by definition. The fact that it stops means that it isn't an infinite-series.
There's more to this than math. But if you're not interested, then never mind.
 
  • #44
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Originally posted by Lifegazer
Does L/2 + L/4 + L/8 + L/16 + L/32... ad-infinitum... converge to 'L'?

Yes

You can stop asking me the same question. Trust me, I'm not going to change my answer.

And if the above series is considered to be infinite, then how can it ever stop at 'L'?

The "how" is in the link I gave you. All the deductions are there.

An infinite-convergence (towards 'L' or '1') cannot stop - simply by definition. The fact that it stops means that it isn't an infinite-series.
There's more to this than math. But if you're not interested, then never mind.

No, there really isn't more to it than math. Again, read the paradox. I can't stress that enough. The solution is found in the calculus of infinite series. If you can't be bothered taking it upon yourself to read the problem and learn the math that solves it, then why bother with these discussions?
 
  • #45
Originally posted by Tom
No, there really isn't more to it than math. Again, read the paradox. I can't stress that enough. The solution is found in the calculus of infinite series. If you can't be bothered taking it upon yourself to read the problem and learn the math that solves it, then why bother with these discussions?
I consider the discussion to be one of reason. Fundamentally, the discussion is about the nature of reality, and discusses the possible 'substance' of particular concepts. Whether they can exist as tangible-entities, outside of perception.
You don't seem to want to debate any issue concerned along these lines. Fair enough. But to think that all such matters are solved because 'mathematics' (which is conceptual) can make an infinite-series come to a stop, is an incorrect attitude, imo.
I could probably come to understand the mathematics you pointed-out. But after I came to understand these mathematics, I would make the exact-same points I've been making all along. I do not contend that the mathematics are wrong. I contend that they don't make sense in relation to existence. A series which is 'infinite', by definition, simply cannot stop.
 
  • #46
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Originally posted by Lifegazer
I consider the discussion to be one of reason. Fundamentally, the discussion is about the nature of reality, and discusses the possible 'substance' of particular concepts. Whether they can exist as tangible-entities, outside of perception.

Everyone involved--you, me, Zeno--considers the discussion to be one of reason. The question is, "How did Zeno reason his argument, and where did he go wrong?"

You don't seem to want to debate any issue concerned along these lines. Fair enough. But to think that all such matters are solved because 'mathematics' (which is conceptual) can make an infinite-series come to a stop, is an incorrect attitude, imo.

First, I never said that "all such matters" were solved with mathematics. I said that Zeno's paradox was solved with mathematics, and that is because Zeno based his argument on mathematics. Again, you would know that if you had read the problem.

Second, the infinite series does not "come to a stop". It converges, meaning that all its terms add up to a finite number.

I could probably come to understand the mathematics you pointed-out. But after I came to understand these mathematics, I would make the exact-same points I've been making all along.

I doubt it. For one thing, you would not be making the point that it takes an eternity to traverse a finite length at constant speed. That is precisely where Zeno went wrong.

I do not contend that the mathematics are wrong. I contend that they don't make sense in relation to existence.

Well then tell Zeno! I am only analyzing his argument.

A series which is 'infinite', by definition, simply cannot stop.

And it doesn't. It's just that the infinite number of parts add up to a finite number. I know what your next question is going to be:

"But how...?"

The "how" is contained in the link I gave you. If you go through it--and understand it--you will see that some infinite series can be summed, despite the fact that they do not "stop".
 
  • #47
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In other words, you can keep adding up 1/2n all day long, but you will never get past 1. If you feel really bored, try it...
 
  • #48
ahrkron
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Originally posted by Lifegazer
The motion of an observer, within his own mind (full of sensations), is the motion of the mind itself... within itself. It is a shift of perception which yields the appearance of motion - within the mind. The mind doesn't really cross lengths. It changes its perspective of that length, thus yielding the perception of motion. But the mind moves nowhere. Only sensations are changed.

Phrase it as you will. The fact is, the perspective/perception/appearance or anything you want to use for the description, gives as good a basis for the paradox as realism.

For instance:

In order for the mind to "change perspective", it needs to do it in a way that (according to its own perspective) sweeps the intermediate perspective-states.

In order for it to "change sensations" from here to 1m, it first has to "change perspectives" up to 0.5m, and then to half that "perspective", and then half that.

i.e., if you don't accept that an infinite sum can converge to a finite number, then you have to accept that even in your mind, motion cannot be completed ever.

In any case, you can see that Zeno's argument does not favor either view (with or without the "Mind").
 
  • #49
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Second, the infinite series does not "come to a stop". It converges, meaning that all its terms add up to a finite number.

I'm no mathematician but I don't think that's strictly true. The infinite series sums to what is, to all intents and purposes, a finite number given that .9999999....... is equal to 1.

Taking Uncertainty into account, the 'smearing' of space time as one approaches infinitesimal quantities might logically translate to numbers in that any conceptualy finite number n, is in 'reality' or practical use, n+-1/[oo]. The problem being that using this concept, 1 is not a strictly finite number. If there was a symbol for 'infinitesimal' that would be better.

Applying this to Zeno, in the case of Achilles, depending on what infinitesimal amount short of the total distance is deemed to be equal to the distance, he reaches the finish line long before a infinite amount of time has passed. In the case of the arrow, it always in motion an never stationary.

Raavin

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  • #50
Originally posted by ahrkron
In order for it to "change sensations" from here to 1m, it first has to "change perspectives" up to 0.5m, and then to half that "perspective", and then half that.

i.e., if you don't accept that an infinite sum can converge to a finite number, then you have to accept that even in your mind, motion cannot be completed ever.

In any case, you can see that Zeno's argument does not favor either view (with or without the "Mind").
If the mind changes perception like the frames of a movie (incrementally, rather than smoothly), then would motion be achieved without such considerations?
 
  • #51
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Originally posted by Lifegazer
If the mind changes perception like the frames of a movie (incrementally, rather than smoothly), then would motion be achieved without such considerations?

You may never believe it, but motion occurs in nature without any need for perception of it. One doesn't need a mind to have motion occur in nature.
 
  • #52
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Originally posted by heusdens
You may never believe it, but motion occurs in nature without any need for perception of it. One doesn't need a mind to have motion occur in nature.

To assert either position is pointless imo. Might as well argue how many angels can dance on the head of a pin. The same goes for infinity and time. We perceive what we perceive and that perception is consistent enough that we can make productive use of it or waste our time with silly debates.
 
  • #53
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Alright people, let's move on. I think Tom's link provides a clear enough explanation.

Are there any of Zeno's paradoxes that are not considered to be resolved?
 
  • #54
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Originally posted by Mentat
Are there any of Zeno's paradoxes that are not considered to be resolved?

I'm sure you are aware of this by now, but that depends on who you ask! Let's just go through the paradoxes and check them out for ourselves.

Earlier, Heusdens brought up The Arrow. Let's go through that one next.
 
  • #55
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Originally posted by Tom
I'm sure you are aware of this by now, but that depends on who you ask! Let's just go through the paradoxes and check them out for ourselves.

Earlier, Heusdens brought up The Arrow. Let's go through that one next.

Alright. What does that one postulate?
 
  • #56
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http://plato.stanford.edu/entries/paradox-zeno

From Section 3.3 of the above document:

3.3 The Arrow
The third is … that the flying arrow is at rest, which result follows from the assumption that time is composed of moments … . he says that if everything when it occupies an equal space is at rest, and if that which is in locomotion is always in a now, the flying arrow is therefore motionless. (Aristotle Physics, 239b.30)
Zeno abolishes motion, saying "What is in motion moves neither in the place it is nor in one in which it is not". (Diogenes Laertius Lives of Famous Philosophers, ix.72)

edit-
Here's another page on the subject.
http://faculty.washington.edu/smcohen/320/ZenoArrow.html
 
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  • #57
Originally posted by wuliheron
To assert either position is pointless imo. Might as well argue how many angels can dance on the head of a pin. The same goes for infinity and time. We perceive what we perceive and that perception is consistent enough that we can make productive use of it or waste our time with silly debates.
I like that, Wu Li.

The third is … that the flying arrow is at rest, which result follows from the assumption that time is composed of moments … .
You know, I'm just not sure what time is composed of, but I think this could get interesting.
 
  • #58
Originally posted by Tom
The third is … that the flying arrow is at rest, which result follows from the assumption that time is composed of moments … . he says that if everything when it occupies an equal space is at rest, and if that which is in locomotion is always in a now, the flying arrow is therefore motionless. (Aristotle Physics, 239b.30)
Zeno abolishes motion, saying "What is in motion moves neither in the place it is nor in one in which it is not".
And how does math resolve this one?
 
  • #59
Raavin
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We perceive what we perceive and that perception is consistent enough that we can make productive use of it or waste our time with silly debates.

I don't think it's silly at all. While these sorts of debates are time consuming, they give people the ability to nut out ideas and stretch creative thinking. That's applies to those people who don't just grab the answers off of other websites.

Looking at the arrow, my personal gut instinct tells me something like this....

If we apply uncertainty principle (non-mathematically), as the time period approaches or reaches zero (an instant), so the inability to determine precise location increases.

If we can determine the location precisely then the momentum becomes indeterminable and not necessarily zero. Inversely, if we measure the momentum precisely, then we must accept that it's precise position must be indeterminable.

Therefore the arrow cannot exist in one position in an instant of time simultaneously but rather exists over some interval in a vague position.

Raavin ;)
 
  • #60
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Originally posted by Tom
http://plato.stanford.edu/entries/paradox-zeno

From Section 3.3 of the above document:

3.3 The Arrow
The third is … that the flying arrow is at rest, which result follows from the assumption that time is composed of moments … . he says that if everything when it occupies an equal space is at rest, and if that which is in locomotion is always in a now, the flying arrow is therefore motionless. (Aristotle Physics, 239b.30)
Zeno abolishes motion, saying "What is in motion moves neither in the place it is nor in one in which it is not". (Diogenes Laertius Lives of Famous Philosophers, ix.72)

edit-
Here's another page on the subject.
http://faculty.washington.edu/smcohen/320/ZenoArrow.html

*scoffs in utter derision* I am now of the opinion that Zeno came up with these "paradoxes" just to irritate people (just kidding).

Why didn't Zeno realize that things do not remain the "now"? If they did, he would have been wrestling dinosaurs, while baking in the molten lava that was the Earth.
 
  • #61
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OK, it goes something like this:

1. If the arrow occupies a space its own size, then it is at rest.
2. The arrow always occupies a space its own size.
3. Therefore, the arrow is always at rest.

As far as I can see, the error in this argument is that the first premise is false. It basically says that if you know the position of the arrow, you know its state of motion. But every student of Physics I knows that you have to specify both the initial position and the initial velocity to get the state, because motion is described by a 2nd order differential equation.

So, in order to conclude that motion is impossible, Zeno had to assume that motion is impossible!
 
  • #62
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Zeno's paradoxes all make extensive use of reductio ad absurdum. Formal logic had not been invented yet and his were all inductive arguments. Instead of attempting to prove motion was impossible or false, he was really attempting to show that the idea of motion was just as absurd as his own idea that nothing moved. Therefore the real issue on the table is not whether or not he proved motion is impossible, but did he prove it was equally absurd, illogical, irrational.....
 
  • #63
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Originally posted by wuliheron
Zeno's paradoxes all make extensive use of reductio ad absurdum.

For sure that's true of The Dichotomy, but I don't see how The Arrow is reductio ad absurdum.

Formal logic had not been invented yet and his were all inductive arguments.

It seems to me that they are all attempts at deductive arguments. The only problem with them is that they all use false premises. If Zeno were right about the infinite series or one parameter specifying a dynamical state, he would have two sound deductive arguments here!
 
  • #64
wuliheron
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Originally posted by Tom

For sure that's true of The Dichotomy, but I don't see how The Arrow is reductio ad absurdum.


Zeno's argument revolves around the concept of infinitely divisible space and an "instant" in time which is not divisible by definition. Hence the paradox of our ordinary perception of time. He was pointing out that people tacitly accept some things are infinitely divisible while others are not.

Can you have half a human being, a half pregnent woman, etc? Why should space be infinitely divisible and not time? On the other hand, if you accept that nothing is infinitely divisible it leads to an equally absurd paradox, motion is impossible.

It seems to me that they are all attempts at deductive arguments. The only problem with them is that they all use false premises. If Zeno were right about the infinite series or one parameter specifying a dynamical state, he would have two sound deductive arguments here!

Nah, his style of absurity was the common fare among ancient Greeks at the time for entertainment purposes as much as anything else. Another more pointed purpose was political and religious. Criticism of the established faith and political leaders was punishable by death. A way around this was to create "puzzles" which did not directly criticize religion and politics, but humorously pointed out the absurdity of the situation as indirectly as possible.
 
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  • #65
Originally posted by Tom
But every student of Physics I knows that you have to specify both the initial position and the initial velocity to get the state, because motion is described by a 2nd order differential equation.
That just implies that nothing can exist unless it moves. As observed by the eye. But you cannot impose physical-law upon all existence. There is no solid argument of reason which can make that claim. So when you deconstruct Zeno's argument by-way of reason deducted via physics, your argument has little merit Tom.

Edit: I expect you to reply that the paradox is about 'matter', and that therefore your reason is valid. But your reason is actually about fundamental-matter (fundamental energy). You are discussing the base-energy of existence itself. And so, as mentioned above, your logic is invalid.
 
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  • #66
quantumdude
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Lifegazer, you have a real knack for completely missing the point.

Let's look at what I wrote again:

1. If the arrow occupies a space its own size, then it is at rest.
2. The arrow always occupies a space its own size.
3. Therefore, the arrow is always at rest.


There is Zeno's argument. The first premise says that if the arrow has a location at some time, then it is at rest. In other words, he is saying that specifying x(t0) at some time logically implies that it is not moving. If we take the correct specification of a state, namely that one must specify both x(t0) and v(t0), then we see that Zeno tacitly assumes that v(t0)=0.

When the tacit assumption is recognized and inserted into the argument, we have "If an arrow is at a location and not moving, then it is not moving", which is trivial.

Originally posted by Lifegazer
That just implies that nothing can exist unless it moves.

Nothing I wrote implies that. You just pulled it out of the air.

As observed by the eye. But you cannot impose physical-law upon all existence. There is no solid argument of reason which can make that claim. So when you deconstruct Zeno's argument by-way of reason deducted via physical-laws, your argument has little merit Tom.

Again, you completely misunderstand both me and Zeno. Zeno is starting from what he believes are physical laws. He just got it wrong is all.

Edit: I expect you to reply that the paradox is about 'matter', and that therefore your reason is valid. But your reason is actually about fundamental-matter (fundamental energy). You are discussing the base-energy of existence itself. And so, as mentioned above, your logic is invalid.

There is nothing in either Zeno's argument or my argument about "fundamental energy" or "existence". You are seeing something that is not there.
 
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  • #67
Originally posted by Tom
When the tacit assumption is recognized and inserted into the argument, we have "If an arrow is at a location and not moving, then it is not moving", which is trivial.
I disagree with this. Zeno says more than this. He also says the arrow cannot exist in any other state (premise 2). Therefore, the conclusion (premise 3), still seems to have validity.
There is nothing in either Zeno's argument or my argument about "fundamental energy" or "existence". You are seeing something that is not there.
Okay, I apologise for that. I thought you was hinting at QM.
 
  • #68
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Nope, no QM is necessary here.

Originally posted by Lifegazer
I disagree with this. Zeno says more than this. He also says the arrow cannot exist in any other state (premise 2). Therefore, the conclusion (premise 3), still seems to have validity.

Premise 2 only says that the arrow always has to have a location, which is true. However, that has no bearing on Premise 1, in which Zeno says that the position alone specifies the state. Premise 1 is false, and the argument is deductively valid, so we know that the conclusion is false.
 
  • #69
quantumdude
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Incidentally, it is said that Zeno's reason for forwarding Premise 1 is that, at any instant, there is no physical difference between a stationary arrow and a moving arrow. I don't see the logical connection there, but we now know that there is a physical difference: the moving arrow would be length contracted as per Special Relativity.

If SR were known at the time, would Zeno have offered this argument?
Did Zeno forsee SR?

Hmmm....
 
  • #70
wuliheron
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Originally posted by Tom
Incidentally, it is said that Zeno's reason for forwarding Premise 1 is that, at any instant, there is no physical difference between a stationary arrow and a moving arrow. I don't see the logical connection there, but we now know that there is a physical difference: the moving arrow would be length contracted as per Special Relativity.

If SR were known at the time, would Zeno have offered this argument?
Did Zeno forsee SR?

Hmmm....

He did in the sense that special relativity proposes an indivisible spacetime continuum, and Zeno believed everything was indivisible. Again, the argument is that having half a human being or a half pregnent woman or whatever is impossible. The alternative which he makes fun of in his paradoxes is that everything is infinitely divisible and, at that point, the Sorites heap paradox kicks in.
 

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