[lit-ideas] Re: Darwiniana
- From: Donal McEvoy <donalmcevoyuk@xxxxxxxxxxx>
- To: "lit-ideas@xxxxxxxxxxxxx" <lit-ideas@xxxxxxxxxxxxx>
- Date: Fri, 24 Feb 2012 14:42:17 +0000 (GMT)
There is too much in JLS' post for one reply, but here are some points for now
- including some on misunderstandings on JLS's part.
From: "Jlsperanza@xxxxxxx" Jlsperanza@xxxxxxx
>>There is an underlying question of what kind of explanation 'Darwinism' is -
what we might also describe as the question of its logical character,
including the extent to which Darwinism is 'scientific' (or testable)."
>To do that, we would need to symbolise the theory, and focus not on what
the theory _states_ (the topic of the theory), but to abstract considerations
like:
-- observational terms/predicates vs. theoretical terms/predicates
the nature of explanation, nomological models, falsificationist models
axiomatic component
empirical support, paradigm, research-programme, the nature of the
evidence, theory-laden observation.
and so on.
i.e. the stuff that standard philosophers of science (Popper, Lakatos,
Kuhn, or Hanson) have been interested all along.>
It can, I think, be put more simply: it's a question of what
testable/falsifiable consequences a certain formulation of 'Darwinism' ['D']
may have.
A formulation of D as "survival of the fittest" may lack falsifiable
consequences, especially if the only criterion of fitness is survival. But
other D-type formulations may have falsifiable consequences: for example, that
even a species where the gender ratio is 9:1 [whichever way] will over time
evolve into one with a roughly 1:1 sex ratio [this is because mutations or
deviations away from the 9:1 ratio will always be more successful in
reproductive terms and so spread until an equilbrium of roughly 1:1 is reached:
this can be be shown 'mathematically' but is also testable empirically].
>Well, Popper's claim to fame is indeed his falsificationism. But we should
go one step earlier and reconsider how Popper's target of attack,
inductionism, had explained (or not) the logical character of the 'Darwinian'
explanation.>
On the contrary, Popper argues, it is Lamarckism that has an inductive 'logical
character'. Whereas D has a falsificationist/non-inductive/eliminativist
'logical character' [as per the 'jelly-point']. This superior, correct 'logical
character' is one of the strong non-empirical grounds for preferring D over
Lamarckism. [This argument is developed at several places in Popper's work].
>Once we have assessed how "Inductionism" or positivism explains or fails
to justify the valid logical character of the Darwinian explanation can we
consider whether Popper's thesis -- that Darwinism is not falsifiable, never
mind verifiable.>
Popper retracted his argument that D is not falsifiable (I believe I have
posted on this before). His amended position is that while certain formulations
of D are barely (if at all) testable (as per his earlier arguments), certain
D-type formulations are testable. We should, therefore, distinguish specific
D-type explanations that are testable by observation from D as a framework
which suggests what type of explanation we should seek. As a framework positing
what would be an acceptable 'explanation in principle', D may be not itself
open to falsification and is not falsified simply because some specific D-type
explanation is falsified. In other words, we need to distinguish D _qua_
metaphysical research programme from D _qua_ specific types of testable
explanation.
There is more to be said, particularly on reductionism. But we seem to be
agreed on the 'jelly-point': D is not a reductive explanation of evolved
characteristics, and in several senses, but particularly in that it does not
explain those characteristics being as they are in a way that is entirely
reducible to [or predictable, or deducible, from] 'selection pressures'
[whereas the shape and size of the jelly may be entirely reducible
to/predictable from the shape and size of the mould, as the entirely
determinant 'selection pressure' on its shape and size]. Rather D gives a
partial explanation of the endurance of certain characteristics (as against
others) because they are more successful at avoiding elimination by the various
selection pressures. This is much less a determinant explanation and allows for
much greater contingency in explaining the course of evolution [e.g. how an
asteroid disaster might wipe out a dominant species like the dinosaurs
and set evolution on a different course]. It also allows that 'selection
pressures' are often not so severe that only a very limited variety of
life-forms could endure them. As Popper aptly puts it, even unfit and
maladapted traits may succeed in the course of evolution - "at least until they
fail".
Donal
Must dash
Ldn
Other related posts:
