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Re: Cause and Effect

----- Original Message -----
From: "Leigh Palmer" <palmer@SFU.CA>
To: <PHYS-L@lists.nau.edu>
Sent: Monday, October 23, 2000 7:16 AM
Subject: Re: Cause and Effect


Brian Whatcott has quoted Newton (in translation). I take it as evident
that Newton stated a causal relation. That is evident to me in his use
of the word "impressed" (I'm sorry, my Latin is gone).

-------------------
Some quotations:
*
Definitio Tertia
Materiae vis insita est potentia resistendi, qua corpus unumquodquam, quantum in se est,
perseverat in statu suo vel quiescendi vel movendi uniformiter in directum.
*
Lex Prima
Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi
quatenus a viribus impressis cogitur statum illum mutare.
*
Lex Secunda
Mutationem motus proportionalem esse vi motrici impressae, et fieri secundum linea rectam
qua vis illa imprimitur.
*
Lex Tertia
Actioni contrariam semper et aequalem esse reactionem: sive corporum duorum actiones in se
mutuo semper esse aequales et in partes contrarias dirigi.
-------------------

I'm not sure what to think about the causation of acceleration by force. It depends a lot
on the context of discussion: talking to students, I would no doubt say that a contact
force causes the elongation of the spring, and things like that.

But regarding Newton's view on the matter, I find no reason to debate: Newton believed
that forces cause accelerations. He wrote of inertia as "a power to resist" and as "a
force"; he wrote "if not contrained by impressed forces"; he even called mutual forces
"action and reaction", implying a succession in time and in causation. If he would have
thought differently, he would have written differently! I think he didn't state "vis causa
est corpus unumquodquam status suum mutare", or something like that, because the thing was
too obvious to him!

==================================================
Paolo Cavallo " I am a teacher at
ton0621@iperbole.bologna.it heart, and there
are moments in the
classroom when I can hardly hold the joy. "
P. J. Palmer, 1998
==================================================