Hennig's heuristic principles (Was: Positivism in evolutionary scienc)

[M.Bennett]

At 11:24 PM 12/5/97 -0200, Thomas Schlemmermeyer wrote:

>Here, Hennig utters some caveats concerning the power of his methods.
>He says that his rules and criteria (to recognize homologies, polarize
>them and run the deviation rule) are nothing more but heuristic principles.
> Miss Bennett from California out there (Duodeviginti-Thread)! You probably
> know what a heuristic principle is.
> But I think it includes some point of subjective judgement
> (greek heureka=I see, I understand).

Archimedes ran through the streets of Syracuse shouting "Heureka!" I have
found (it)!
That word is the aorist (or perfect past) tense of the Greek verb heurisko,
meaning to find out, to discover. heuristic, however, comes from that verb
indirectly through the derived adjective heureteos, discovered, in its
superlative form, heuristos i.e. most/very discovered.

The three modern meanings I have found for heuristic are: 1) relating to a
usually speculative formulation serving as a guide in the investigation or
solution of a problem. 2) relating to an educational method in which
learning takes place through discoveries that result from investigations
made by the student; 3) relating to a computer-based problem-solving
technique in which the most appropriate solution of several found by
alternative methods is selected at successive stages of a program for use in
the next step of the program.

I think Hennig had the first definition in mind, but I tripped over the word
"speculative" . In the interests of precision, I looked up the definition of
"speculate" which is "to engage in a course of reasoning often based on
inconclusive evidence", and merged it with the definition of heuristic, and
I got:   relating to a formulation serving as a guide in the investigation
or solution of a problem, which  involves a course of reasoning often based
on inconclusive evidence.

That's where the subjectivity comes in, when one chooses an approach, a
particular course of reasoning, even if there is no conclusive evidence to
support that choice of approach. Practically speaking, does this mean that
Hennig was suggesting use of his methods to provide a starting point for
what, hypothesis formulation?
M.Bennett
Bohart Museum of Entomology
Dept. of Entomology
University of California
Davis, CA  95616 U.S.A.
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mrbennett at ucdavis.edu