Re: [Phys-L] causality

[brian whatcott <betwys1@sbcglobal.net>]

I feel an unreasonable sympathy for John's position on this issue, and I 
reflected on how this could be, when my usual response is neutral 
towards his persona.

I realized, at length, I am seeing a reenactment of the situation when I 
attempt to use fact in the face of deeply held attitudes - about 
politics, or gun regulations, for example.

Which brings me to my recognition of a well known feature of human 
cognition: we think of consciousness as a unitary thing, the location of 
our "self".
 But there are strands of cerebration which do not rise to our 
awareness, pulling at times in several directions. One reason we "sleep 
on it".
One reason we rationalize.

Brian W

On 2/8/2019 6:15 AM, John Denker via Phys-l wrote:
> On 2/8/19 2:31 AM, Steve Spicklemire via Phys-l wrote:
>
> > This is an interesting conversation!
> :-)
>   
> > Perhaps it’s naive to think it, but I feel that when you can write something like:
> >
> > dp/dt = Fnet
> >
> > it means that the *future* p depends on Fnet and p *now*. So:
> >
> > p_future = p_now + Fnet_now*dt
> >
> > So I think one could argue that p_now and Fnet_now “cause” p_future, and not the other way around.
> >
> > no?
> >
> > What’s the trouble with such a point of view?
> The math is not wrong as far as it goes, but it's only half of
> the story:
>    1) Yes, using the differential equation, you can integrate forward in time.
>    2) You can equally well integrate backward in time!  Like this:
>
>     p_past = p_now - Fnet_now*dt
>
> Bottom line: Newton's laws tell us just as much about the past
> as the future.  Since causes must precede effects, Newton's laws
> cannot be statements about causation.
>
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