[Martin Taylor 960111 11:11]
Bill Powers (960109.2315 MST)
The crackshaft analogy is wonderful. I plan to set it aside, and would
like permission, if it turns out to be suitable, to abstract it or extract
from it for the editorial in the special issue of IJHCS. (By the way,
any luck yet with Tom on that matter?).
The point of this is that when you seize on a particular causal
explanation, you can make sense of any circular process by attributing
causation to any part of the process. The more you think about it, the
more sense it makes and the more supporting evidence you can find.
So true, and a major reason why it's so hard to get PCT accepted. It is
the case that there are relationships between sensory input and muscular
output much of the time--looks causal, is pretty consistent and when it
isn't, there's usually an excuse. There's a relation between events in the
outer world and perception, too (perceptual signal corresponds to CEV),
but those relationships are between invisibles, and moreover, between
invisibles that (ideally) don't change their values as a consequence of
changes in observables. (CEV follows reference values more than disturbance
--observable--values). Why should any sane person chase think twice about
a theory based around things that can't be seen or measured, when there's
a perfectly good (except where it doesn't work, and those places--of course--
will be fixed in the centuries to come) theory that relates observable and
measurable things?
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The quote from Sky and Telescope rings true, but I think it can be extended
beyond the mathematics of quantum physics to the realm of everyday perception.
And it's worth remembering that mathematics can sometimes introduce
concepts that are only a means to an end and have no independent
reality. In the abstract world of mathematical symbolism, it isn't
always clear what is real and what's not.
Substitute "perceptual functions" for "mathematics" and I think you have an
equally accurate statement. What we see, whether PCT is correct or not,
depends entirely on how our perceptual systems organize sensory input
and memory. What impinges on the sensors is determined by the outer world.
What we make of it is not, and two people exposed to the identical physical
"impingements" might see entirely different things--just as one can see the
multiple possibilities in an ambiguous picture.
In the mirrored world of CEVs defined by perceptual input functions, it isn't
clear what's real and what's not, if by "real" one means "can be consistently
affected by output in a way that consistently affects perception."
Atoms are "unreal" in the same way that twistors and quarks are "unreal".
Nobody can manipulate an atom. The best anyone can do is to manipulate a
representation on some sort of screen that changes as if there were such a
thing as an atom that is being manipulated. Likewise with the deeper and
weirder mathematical representations of quantum physics. They are "real"
to the degree that manipulating them gives results that are _as if_ a
"real" thing had been manipulated. Different physicists may see different
things in the same data--different persons may perceive different kinds
of things in the same sensory input: where you see "police brutality" I may
see "effective maintenance of law and order." Where you see "twistors" I
may see "furkle-class gluons".
I don't think there's any deep difference between the mathematical abstractions
that prove useful and the perceptual functions that prove useful (and are
therefore resistant to being reorganized away).
Martin