BaalChatzaf

Asimov on Scientific Certainty.

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On one thread, Baal claims that we don't have Aristotle's words so we have *no ideaat all* what he actually said or did as opposed to his followers.

On another thread he castigates Aristotle for his bad scientific method.

You can't claim both: Simple (Aristotelian) logic.

We have the written words of the received Aristotle. Read -Physics- book IV either in the original Attic Greek or in translation.

He did not check his work out empirically. He could have but he did not. Or at least no where in the received writings is any indication that he did. It is the case that his followers did not check out his work until John Philoponus a Byzantine scholar did in the 7th century. That is 1000 years without a recorded check. Philoponus found Aristotle to be in error. Philoponus did an experiment (dropped two unequal weights together from the same height). This experiment is attributed to Galileo later on.

Ba'al Chatzaf

Ba'al Chatzaf

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> We have the written words of the received Aristotle.

Yes, but I distinctly remember you saying we only have student's notes and we don't know his own views. Do I need to look it up?

You can't weasel out of it with the 'received' Aristotle.

> Philoponus found Aristotle to be in error. Philoponus did an experiment (dropped two unequal weights together from the same height).

I already explained to you that they didn't have the instruments to measure this properly. And you have not explained how he got around this problem.

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> We have the written words of the received Aristotle.

Yes, but I distinctly remember you saying we only have student's notes and we don't know his own views. Do I need to look it up?

You can't weasel out of it with the 'received' Aristotle.

> Philoponus found Aristotle to be in error. Philoponus did an experiment (dropped two unequal weights together from the same height).

I already explained to you that they didn't have the instruments to measure this properly. And you have not explained how he got around this problem.

You don't need instruments to see if two bodies hit the ground at the same time or within a fraction of a second of each other.

I will do this for you again, slowly. From -Physics- book IV we get some laws (not stated in algebraic form to be sure, but implied by the test) If a heavy body and a light body travel through the same medium their terminal velocities will be in proportion to the weights of the objects. So a one pound shot and a ten pound shot dropped at the same time should, according to -Physics- result in the heavier weight reaching the ground ten times faster than the lighter weight. This is trivial to refute. It does not take fancy instruments.

John Philoponus did the obvious experiment in the seventh century and found Aristotle's laws for motion through mediums to be in error. The root of the error was Aristotle's assumption that the velocity of the falling body would be reached immediately. Aristotle had no clear concept of acceleration. Again read -Physics- to see this.

As I explained before Aristotle was in no position to get an exact relation between the density of a falling body in a medium and its terminal velocity. Which is why his law of motion through mediums was not correct. The issue is not that Aristotle made a mistake or could not get a proper law for lack of technology. The issue is that he did not check.

Now ask yourself this: why is there no record of anyone checking between the time Aristotle wrote -Physics- and the criticism of John Philoponus? Why did it take a thousand years for someone to look and check? My hypothesis is that philosophers suffered from the "Greek Disease". They believed a good argument was proof of its correctness. If the premises seemed self evident and the logic was sound, then, by golly the conclusion just had to be true. Aristotle was not the only Greek to suffer from this frame of mind.

It took a long time before empiricism became the dominant outlook.

And yes, all my statements are predicated on what we get from the "received Aristotle" That is all the data we have. Who knows, maybe the "real Aristotle" created string theory and quantum mechanics at the Lyceum but the documentation got lost. We can only operate on the data and the writings we have.

Ba'al Chatzaf

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Baal, I give up. I've explained it to you in multiple ways. With irrefutable logic.

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Baal, I give up. I've explained it to you in multiple ways. With irrefutable logic.

Your logic is great. Your facts suck.

Ba'al Chatzaf

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And I pointed you to the relevant facts. As did Merlin. And several others.

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Bob is right in that the essential point is that Aristotle did not verify by experiment so he was not a true scientist. A true scientist himself does not need to do experiments but must respect the empirical, experimental data. However, Aristotle did nothing to retard science because there was something he did not do. If this was the case Archimedes would have issued in an age of greatness all those years ago, making up for other deficiencies. No? (Did you all know that Benjamin Franklin was the first great American scientist? One of the greatest of his century?)

--Brant

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And I pointed you to the relevant facts. As did Merlin. And several others.

You have totally ignored what the (received) Aristotle wrote. I gave you references to -Physics- line and number.

Ba'al Chatzaf

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And I pointed you to the relevant facts. As did Merlin. And several others.

You have totally ignored what the (received) Aristotle wrote. I gave you references to -Physics- line and number.

Ba'al Chatzaf

You have ignored what the (received) Aristotle wrote. You gave somebody else's references w/o showing the words from the horse's mouth. For the time being the book I own in which I can easily find the references is in storage, and I haven't found one on the internet convenient to use. Got one? Anyway, it shouldn't take much effort for you to quote Aristotle's (received) words on OL and say what you glean from them. This is something you have completely failed to do so far.

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And I pointed you to the relevant facts. As did Merlin. And several others.

You have totally ignored what the (received) Aristotle wrote. I gave you references to -Physics- line and number.

Ba'al Chatzaf

You have ignored what the (received) Aristotle wrote. You gave somebody else's references w/o showing the words from the horse's mouth. For the time being the book I own in which I can easily find the references is an storage, and I haven't found one on the internet convenient to use. Got one? Anyway, it shouldn't take much effort for you to quote Aristotle's (received) words on OL and say what you glean from them. This is something you have completely failed to do so far.

I don't speak or write Attic Greek. I use translations. Sorry about that.

I have pointed to what the (recieved) Aristotle had to say about motion of bodies through a retarding medium.l

Ba'al Chatzaf

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I don't speak or write Attic Greek. I use translations. Sorry about that.

I have pointed to what the (recieved) Aristotle had to say about motion of bodies through a retarding medium.l

Ba'al Chatzaf

I didn't ask for Greek, did I?

Your pointing is about as good as the following. I tell you about something you could see in Alaska and don't show you any pictures. When you ask me where exactly it is or for pictures, I point in the general direction of Alaska and say "go see for yourself."

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I don't speak or write Attic Greek. I use translations. Sorry about that.

I have pointed to what the (recieved) Aristotle had to say about motion of bodies through a retarding medium.l

Ba'al Chatzaf

I didn't ask for Greek, did I?

Your pointing is about as good as the following. I tell you about something you could see in Alaska and don't show you any pictures. When you ask me where exactly it is or for pictures, I point in the general direction of Alaska and say "go see for yourself."

I tell you where to find the pictures. I have not been to Alaska to take them myself. Other people have.

Ba'al Chatzaf

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I tell you where to find the pictures. I have not been to Alaska to take them myself. Other people have.

How do you/we know said pictures haven't been edited in Photoshop?

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> I don't speak or write Attic Greek. I use translations. Sorry about that.

That's like saying because you don't read French or German or Russian, you have no way of knowing what Victor Hugo or Kant or Dostoeyevksy said.

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Where did Aristotle say that for bodies falling through a resisting medium (a non-vacuum) the time of the fall would be inversely proportional to weight of the bodies?

Have a look at -On the Heavens- 273b-30 - 274a-1.

Here is the translation by J.L.Stocks in the -Complete Works of Aristotle: The Revised Oxford Translation- Volume 1, Princeton University Press, 1981.

"A given weight moves a given distance in a given time, the times being in inverse proportion to the weights. For instance, if one weight is twice another, it was take half as long over a given movement"

It was this assertion of Aristotle that Galileo claimed his disproved in -Dialogue Concerning the Two Chief World Systems-.

Was Aristotle simple minded? Nay, nay. Whatever else was wrong with Aristotle, simple mindedness was not among the wrongs. Here is the nub of it. Aristotle did not handle acceleration, he handled speeds Accelerations either occur so slowly as not to be significant, say a loaded ox-cart being started up for its journey down the road. The time over which speed changes is not significant to the steady state portion of the trip. Or acceleration happens so quickly that the portion of the trip over which it occurs is negligible over the length of time of the trip.

Aristotle denied the existence of a vacuum, so he never considered in a substantial fashion how a body with no force acting on it would move. In fact, Aristotle's dogma of motion required a force for any motion. Bottom line: No inertia. Aristotle believed all motions were through a resisting media and that the velocity of a moving body was proportional to the force acting on it which had to be constantly applied else the body would come to rest. Now reconsider what Aristotle said in -On the Heavens-. Aristotle's statement now applies to bodies moving at what we would call terminal velocity. He believe when a weight was allowed to fall it achieved its terminal velocity instantly or nearly instantly. Of one considers only falling motions through a resisting medium, such as air, water, olive oil or any other viscous medium then he was nearly right in his dictum. This, he no doubt did observe. Two different similarly shaped weights sinking in water for example. The heavier one would get to the bottom first and in a total time inversely proportional to the weights of the bodies.

I ran into a wonderful technical paper which investigates the "falling body problem" in the context of terminal velocities. Please do read: http://web.me.com/davidsapple/Site/Recent_papers_files/galileo.pdf

This resolves the dissonance between what Galileo wrote in -Dialogues- and what Aristotle wrote in -On the Heavens-. It turns out Aristotle got terminal velocity pretty close which is remarkable because he did not have the technology for doing precise measurements (no accurate clocks in his time). Galileo was talking about falling bodies accelerated in a near vacuum (air is very thin compared to water or olive oil) and Aristotle might have been talking about falling bodies after they had reached terminal velocity. Atkinson's paper, cited above resolves this perfectly.

Ba'al Chatzaf

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Ba'al,

Thanks for finally presenting a quote from Aristotle (translated, of course). Having a quote makes it much easier to find it in a book to read some more, especially when the book doesn't have annotations like 273b-30,

I see that the context is his arguing that the infinitely heavy and the infinitely light are both impossible. It's also far from clear that he is talking about bodies moved by gravity. While I wouldn't assert he meant moving two objects on the surface of Earth perpendicular to gravity, what he said would fit that context much better. It's also far from clear that he meant terminal velocities, but thank you for giving The Philosopher a little slack and/or credit.

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Ba'al,

Thanks for finally presenting a quote from Aristotle (translated, of course). Having a quote makes it much easier to find it in a book to read some more, especially when the book doesn't have annotations like 273b-30,

I see that the context is his arguing that the infinitely heavy and the infinitely light are both impossible. It's also far from clear that he is talking about bodies moved by gravity. While I wouldn't assert he meant moving two objects on the surface of Earth perpendicular to gravity, what he said would fit that context much better. It's also far from clear that he meant terminal velocities, but thank you for giving The Philosopher a little slack and/or credit.

Focusing the context to what we call terminal velocity (which is the only kind that The Philosopher knew) is the way to make sense of what he had to say about some kinds of motion, particularly falling motion through a resisting medium. The Philosopher intuited better than he knew. He was actually getting at motion in viscous media well before the necessary machinery to define viscosity existed. It also explains why he could not readily check on his output. Measuring viscosity is a non-trivial operation and something that a ten year old kid is unlikely to be able to do.

For Aristotle gravity meant heaviness which determines the direction of "natural" (uncoerced) motion. Things made of earth (one of the elements) have gravity or heaviness and their natural direction is down toward the center of the earth until stopped by something else. Lightness, levity the opposite of gravity is a property of (the element) air and fire and its natural motion makes them go up.

The degree of heaviness (or gravity) is proportional to the force on the body. The notion of one body exerting a momentum changing action on another, simply was not an Aristotelian notion. That did not come until Galileo and Newton and to some extent was foreshadowed by the idea of "impetus" which the middle age scholars formulated to deal with difficulties in Aristotle's ideas on how bodies moved. See what John Philoponus had to say about "impetus" (the proto-concept leading to momentum).

Aristotle was ahead of his time (in a sense) and out of his depth, when one considers the mathematically machinery necessary to deal with the concepts implicit in his study.

Digging this this stuff out (I had to spend some time which explains why I delayed responding) was useful. It gave me a better appreciation of what The Philosopher was up to and the difficulty of the subject matter he dealt with. That reference from Elsevier on Aristotle vs Galileo on falling bodies was the key to the "mystery". I came across it quite by accident, but it was a happy accident.

Ba'al Chatzaf

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On 12/31/2011 at 8:14 PM, BaalChatzaf said:

Your logic is great. Your facts suck.

Can i quote that?

 Isaac Asimov . “The saddest aspect of life right now is that science gathers knowledge faster than society gathers wisdom.”
 

“Never let your sense of morals prevent you from doing what is right.”
 

“In life, unlike chess, the game continues after checkmate.”
 

“Anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that 'my ignorance is just as good as your knowledge.'

“Your assumptions are your windows on the world. Scrub them off every once in a while, or the light won't come in.”

“Any planet is 'Earth' to those that live on it.”

“Life is pleasant. Death is peaceful. It's the transition that's troublesome.”

“The most exciting phrase to hear in science, the one that heralds the most discoveries, is not "Eureka!" (I found it!) but 'That's funny...”

“Violence is the last refuge of the incompetent.”

“Properly read, the Bible is the most potent force for atheism ever conceived.”

“Those people who think they know everything are a great annoyance to those of us who do.”

There is not a discovery in science, however revolutionary, however sparkling with insight, that does not arise out of what went before. 'If I have seen further than other men,' said Isaac Newton, 'it is because I have stood on the shoulders of giants.”

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