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Re: [Phys-l] F causes a



Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in
directum, nisi quatenus a viribus impressis cogitur statum illum mutare.

I hope I haven't mistranslated :-)

Bob at PC

-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu
[mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of John Denker
Sent: Wednesday, May 10, 2006 11:26 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] F causes a

Espinosa, James wrote:
I agree with Al and all the others on this list who have said that
Newton's second law is a statement about F causing the acceleration of a
body. As Al refers to Newton's first law, I will quote it from the
latest translation of the Principia: Law 1 Every body perseveres in
its state of being at rest or of moving uniformly straight


forward, except insofar as it is compelled to change its state by forces
impressed.



It is clear to me that "compelled" means to cause, and that "impressed"
means from the environment. The acceleration is a property of the body
but the forces producing it must come from other bodies in its
environment.

1) I object to the form of the argument. It is a naked appeal to
authority. Are we fundamentalists, or scientists? What's next ...
are we going to discuss four-legged insects because they are mentioned
in Leviticus 11?


2) As is so verrry often the case with appeals to authority, we must
consider the possibility that the quote has distorted by taking it
out of context, mistranslated, and/or simply misquoted.

In this case, try going to
http://humanum.arts.cuhk.edu.hk/Lexis/Latin/
and typing "cause" in the search box. I got back 37 responses,
including not only /causa/, /infero/, /propter/ and suchlike, but
also many words that are only distantly connected to the idea of
"cause" ... but still not including /cogo/ (the root of /cogitur/).
If Uncle Ike had wanted to talk about "cause", he could have done
so ... but he didn't.


3) "It is clear"???? Anything can be made "clear" by keeping only
the favorable evidence (no matter how weak) and ignoring the opposing
evidence (no matter how strong).

We should not forget that this is the same Isaac Newton who, in response
to a question specifically about causes and mechanisms, answered "Hypotheses
non fingo."

Also IF (big IF!) we are going to play the fundamentalist game, let's play
it properly. Let's not forget that Newton was greatly indebted to Galileo,
who (as previously discussed) very explicitly dismissed causality arguments
as unhelpful.

OTOH I suppose I shouldn't be surprised to find that people who play an
unscientific game would play it improperly.
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