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Re: CAUSATION IN PHYSICS



John Decker asks me:

Brian: If you are using some other definition of cause-and-effect, please
explain what it is.


John, I am using Newton's statements quoted from the Principia in say
Arnold Arons' text "Teaching Introductory Physics":

Definition IV: An impressed force is an action exerted on a body in
order to change its state, either of rest, or of uniform motion in a
right line.

Law I: Every body continues in its state of rest, or of uniform motion
is a right line, unless it is compelled to change that state by forces
impressed upon it.

"exerted" and, more strongly, "compelled" sound like causal factors to
me.



I've read the Encyclopedia Brit reference he supplied. I think most
physicists would have some problems with Hume's definitions and the
examples he cites: "nothing in the experience of seeing a fire close
by which logically requires that one will feel heat, and since there
is nothing in the experience of seeing one rolling billiard ball
contact another that logically requires the second one to begin
moving" Physics is based on such experiences and controlled
experiments to develop models to "explain" such experiences.

Brian McInnes