Re: Incommensurability of Mathematical Logic and Scientific Logic

surrealistic-dream@xxxxxxxxxxx wrote:

jem wrote:

surrealistic-dream@xxxxxxxxxxx wrote:

AllYou! wrote: 

...

 It is NOT the job of physics to map theoretical causes

from the theory to reality, 

Not only is it not it's job, it's hard to see how it could be done.

 though both physicists and non-physicists

love to do this anyway.

Example? 


Etherists see LET and conclude that there really is a mechanical ether
out there by which light is propagated as a wave in an elastic medium.
SRists see SR and think that there is a thing called spacetime that
really exists out there that governs the local speed of light.
...


Ok. That seems more a matter of mapping theoretical entities than causes, but I see what you mean.


So far, Jem has not suggested that a successful model is a true model. 

AFAIK SD, all models are "true" (i.e. the interpreted theorems of the
underlying theory are true), up to the point they're falsified anyway
(and then they're no longer models).  However, if you meant "true" in
the sense of "ultimate", I'd agree with what you said.



I mean true in the sense that there is a 1-1 correspondence between
objects and causes in the model and objects and causes in the real
world.

What does it mean for there to be an object or cause in the real-world? How would either of these be identified?

A model is faithful if its predictions almost always come true 
on its domain of applicability. "Faithful" is more appropriate for
physics, and "true" for philosophy. The former term captures the
predictive value of a "true" theory without requiring the metaphysics
of the latter term to be true as well.



In GR, gravity is theoretically "caused" by spacetime curvature, which
is caused by the presence of matter. That doesn't mean that in
"reality" there is something called spacetime as a thing, which can be
either flat or curved. The "reality" of GR is no different than the
"reality" of classical thermodynamics: it is the set of actual
measurements and the "things" that make them.


What "things" might those be?  I think the prevailing view in Physics is
that any consideration of "things" in Nature is unwarranted, since
"things" are necessarily model dependent.



The things that make measurements (or participate/used in the process)
are: observers, reference frames, and measuring instruments (and more
to vet the measurement).



Of course.  Can't recall my reason for questioning it.

 Theoretical causes are

not necessarily "real" causes.

"Real" causes, Hmmm. 


A theory can be a good theory even if the causal explanations in the
theory do not correspond precisely (or even remotely) to any causes in
the real world.


That's what the "Hmmm" was about.  What's a real-world cause?

Also, a theory may model matter in such a way that no 
one believes the model is literally true of matter, but the theory may
work anyway. Example: the model of continuous matter or charge
distributions. Classical field theories model interactions differently
than a strict particle-interaction model, yet they work after a
fashion.

But that's just a matter of the degree to which the model predictions match actual measurements.

Feynman modeled light as traveling from source point to 
destination point as taking all possible paths to get there and
traveling at all possible speeds to do so; yet, no one knows whether
this is really what happens or not. It doesn't matter what light
"really" does so long as the theory works.

Not only doesn't it matter, it doesn't even make sense to contemplate things that can't be verified.
.

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