Positivism vs Realism

Byron Adams bjadams at BIOCOMP.UNL.EDU
Sat Dec 13 19:08:19 CST 1997

Richard Zander wrote:
>Byron Adams wrote:
>> Re: the thread of realism vs positivism:
>>         It seems reasonable to me that any scientific research program or
>> methodology employing discovery operations subservient to positivism should
>> be exposed as such.  I think this is a very clever and valid way to
>> criticise a research program or methodology, and I would like to see it
>> continue.  So far (from reading the threads) I am not convinced that this
>> argument has been clearly made or defended.
>Two things about this, Byron. "Discovery operations" assume that there
>is a reality out there, say, a pattern, that exists independently of
>your theory and method of research. That's okay, you're a realist. I
>think that this leads to overconfidence about what "converging to the
>truth" means, especially using a non-statistical method like parsimony
>analysis. Postitivism is on the outs now, since W. Quine published his
>Two Dogmas paper (see his web page) that showed that all statements are
>theory-laden, and the difference between analytic (idea-generated)
>statements and synthetic (observational) is rather vague. On the other
>hand, he said "there is no place for a priori philosophy." To the extent
>that your assumption that metaphysics HAS a place in science, you are
>handicapping yourself with a burdensom circularity.

        First of all, do we agree on a definition of metaphysics?  I'm not
referring to that associated with crystals, pyramids, the occult,
or windham hill samplers, although your post (and an earlier one from
James, who, in a criticism of cladistics said,  "My comments are not
intended to place cladistics firmly into metaphysics...") hints at this.
I'm using the term metaphysics to mean the science that deals with
ontological reality at its most fundamental level.

        Are we in sync?  If so, I maintain that not only does metaphysics
have a place in science, but that we cannot have the one without the other.
I'm not familiar with the context of Quine's statement about the inadequacy
of _a priori_ philosophy, but you seem to be implying that:

        1.  There is no place for preconceived notions in science
        2.  I have a preconceived notion (realism), thus the circularity of
my scientific paradigm

        As a scientist, I know of no other way to approach my subjects
(dear little nematodes) than that they, and all of their evolutionary
history exists independently of any of my notions, be they _a priori_ or _a
posteriori_ of any phylogenetic analysis.  If "what really happened" during
the course of nematode evolution can be different for you than it is for
me, then the sum of all our evolutionary science is incoherent because what
really happened could conflict -- you could have one tree depicting
phylogenetic relationships, I another (quite different one), and we could
both have recovered the *real* tree.  As it regards evolutionary science, I
am convinced that this is ontologically impossible.  I am familiar with
some of the arguments of philosphical "conventionalism" or "relativism."
Some of these I find appealing (I must admit to not completely
understanding all of them).  But to borrow an analogy from Dennett
(_Darwin's Dangerous Idea_), relativism in evolutionary biology is akin to
playing tennis with the net down.  In the end, there is only confusion, and
nobody has any fun.

        I doubt you are advocating that as systematic biologists we
approach our subject as relativists.  But you imply an achilles heel of
realism.  Are you proposing another, more philosphically and operationally
satisfying paradigm?  Or, do you suggest that there is no room for *any*

        Also, you seem to imply that if I use statistical, as opposed to
cladistic methods to recover evolutionary history, I am less likely to
deceive myself into thinking I have recovered "what really happened" when
in fact I have erroneously recovered something else (I call this a "type
III error).  I can interpret this a couple of ways:  Do you mean to say
that, "like a stick of dynamite, parsimony is a powerful tool when used
properly, but dangerous when inappropriate"?  Or was your intent more to
the tune of, "if you're going to eat snow, don't eat yellow snow"?

        If your intentions were of the first scenario, then my
interpretation is that "parsimony analysis" (especially in the hands of
someone unfamiliar with its use) can be more dangerous than
statistical-based phylogenetic inference.  I can accept this without
further discussion.  But if your intentions were of the latter persuasion,
then I find this position a bit harder to swallow (pun intended!).


Byron J. Adams
Department of Plant Pathology
406 Plant Sciences Hall
P.O. Box 830722
Lincoln, NE 68583-0722
lab (402) 472 5598
fax (402) 472-2853

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