[From Bill Powers (2002.06.20.0804 mdt)]
Bruce Abbott (2002.06.20.0840 EST)--
>{pct} predicts that people cannot exist who have otherwise normal sensory
systems >but no ability to experience pain.
This is putting words in my mouth. There is nothing in PCT that "predicts"
anything of the sort. I have proposed that pain signals are simply sensory
signals that are higher than their reference levels. Some signals (such as
hunger signals) have reference levels that are normally zero, so that any
amount of the signal is to be avoided: thus any amount of that class of
signals is considered unpleasant. Other signals are normally varied over
non-zero levels, but even they can become unpleasant when larger or more
intense than the highest normal reference level. A signal consider pleasant
when within some normal range of magnitudes can often become unpleasant or
painful when far above the normal range; that fact (and it is a fact, not a
theory) fits perfectly into the PCT model and into no other model of which
I know.
Perhaps a person who does not feel pain lacks the sensory receptors that
normally report certain types of physiological problem, such as skin
damage. This in no way implies that the missing receptors are "pain
receptors" that produce "pain signals." In comparing two explanations for a
phenomenon, it is not legitimate to treat one of them as self-evidently
correct, as one would do by assuming that the missing signals report an
abstract condition we call pain. The control-system explanation is not
negated if certain sensory signals are missing. To say that all normal
sensory signals are present but pain signals are missing is to assert
exactly what you're trying to prove: that pain signals are not ordinary
sensory signals. If they are ordinary sensory signals, as I claim, then if
they are missing, the person does NOT have all ordinary sensory signals.
The right way to describe the situation is to say that some people lack the
sensory signals that usually report damage or other deleterious conditions.
These propositions are simply an application of PCT to the phenomena of
pain and pleasure following the basic principles of organization of the
control hierarchy and well-accepted principles of parsimony. My claim is
that the concept of specialized pleasure and pain signals, and all the
specialized apparatus that supposedly serves them (in the amygdala and
hypothalamus, for example), is superfluous, ad-hoc, and unneeded. PCT is
not the only body of theoretical speculation under scrutiny here.
>Some of these are predictions that can be assessed even in the absence of
a >quantitative model. There is some evidence available that bears on some
of these >predictions (although one can always argue whether that evidence
is reliable) and >this evidence may be used to raise questions about HPCT
as it is currently >envisioned.
That may be true, but one has to be careful about presenting the evidence;
it is also necessary to weigh the same evidence, using the same criteria,
in relation to any alternative proposal. There is, as far as I know, no
evidence at all for the alternative to PCT. Perhaps the kind of model-based
testing of PCT that might be appropriate for PCT is underdeveloped, but
alternative theoretical claims are altogether lacking in comparabler tests,
those that challenge the basic theory itself. What tests challenge the
concept that stimuli cause responses? Let's not apply a strict standard to
PCT unless we also apply it to the rival theories.
>[Folson asserts] "that if you want to add to PCT, you do it by producing
a model that >controls its perceptions just like the organism/human
does." If you applied this >same standard to Bill's development of HPCT,
B:CP would be reduced to a very thin >book.
And where would it leave any competing theory? As far as I know, no other
approach has even a sketchy working model behind it. Let's compare apples
and apples, please.
As to the meta-dioscussion going on here, wouldn't it be simpler just to
discuss the questions brought up rather than trying to wheedle the jury
into treating either side more or less favorably?
Best,
Bill P.
