[From Bruce Abbott (970225.1540 EST)]
Gary Cziko 970221.0330 GMT
Note that whether or not others like my four levels of selection, thinking
of evolution in this way and this entire interesting discussion would be
impossible without HPCT.
Bruce Abbott (970221.0850 EST)
I appreciate the sentiment, but have to disagree. The recognition of
purpose and goals in behavior predates HPCT by a long, long time.
Gary Cziko 970224.2010 GMT --
Are you saying that the equivalent of HPCT (HIERARCHICAL Perceptual Control
System) existed long before Bill Powers's development of HPCT? If so, I'd
would find names and references very helpful for a book that I am working
on which includes a historical discussion of the notion of purposeful
Not at all. I'm saying that the discussion we were having on purposive
evolution would NOT have been impossible before HPCT, contrary to your
assertion, although of course some knowledge of control theory is required.
The first explicit model of purposeful animate behavior that I have found
is the cybernetic model of Rosenblueth, Wiener and Bigelow of the middle of
this century. But I have found no one before Powers who proposed an
explicit model of a hierarchy of control systems by which higher-level
perceptions are controlled by varying lower-level reference levels.
Have I missed someone?
No, I don't think so. Miller, Galanter, and Pribram introduced what they
called the "plan hierarchy" in their 1960 book; this was discussed in the
context of control theory and the organization of behavior by John Bowlby in
_Attachment_ (1969). Herbert Simon, in _The Architecture of Complexity_
(1962) discusses the advantages of hierarchical organization, talking
explicitly about its advantages for the speed of biological evolution. W.
Ross Ashby (1956) brings up the selective advantage, during evolution, of
the stability provided by control systems. And, of course, Tolman was
talking about purposive behavior in the late 30s, although he did not have a
clear conception of the underlying mechanism. The idea of having
higher-level systems set references for lower ones in a hierarchy of control
was, I believe, borrowed from engineering practice, but so far as I am
aware, Bill was the first to propose an explicit model of this type for the