Date: Mon, 30 Aug 1999 14:21:32 -0600 (MDT)
From: Hans Ehrbar <ehrbar-AT-econ.utah.edu>
Subject: BHA: RE: In which kind of world is probability theory useful?



Marsh,

thank you for your additional examples.  I did try to go the
reductionist route: instead of postulating the existence of
irreducibly probabilistic generative mechanisms, I tried to
see how far one gets explaining random outcomes by leakages
from other layers of reality in a stratified world.

You gave convincing examples that this is not always the case:
quantum mechanics is apparently irreducibly probabilistic,
and also thermodynamics cannot be reduced to the mechanics
of lots of molecules, since the laws of mechanics are
reversible in time, but those of thermodynamics are not.

I doubt that quantum mechanics can be seen in part as
epistemic uncertainty.  One such interpretation, according
to which there are "hidden variables" which we don't know
about, can be refuted by the a simple mathematical theorem
which shows that even pure states in quantum mechanics,
which are not mixtures of other states, are subject to
Heisenberg's uncertainty relation, according to which either
location or impulse can be sharp, but not both.

Hans E.



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