D'Abrera on Science and Philosophy

John Grehan jrg13 at psu.edu
Thu Jul 30 07:29:11 EDT 1998

To anyone interested

I might as well add my twopence to the D'Abrera comments on mimicry and
explanation etc., even though I doubt anyone on the list would agree with me.

I will assume (and M. Gochfeld can comment) that the only evolutionary
mechanism and explanation that D'Abrera has been exposed to is natural
selection and the selection stories that are usually invented to "explain"
the origin of a structure or similarity. If this is the case i would,
myself agree with D'Abrera that such explanations are not really much to go
on in having confidence about evolution. 

Selection might provide understanding of current interactions between
similar species, but the origin of that similarity in the first place would
seem to require something else. Some go for a former selective adaptation
from some other interaction, but this only puts the question further back.
So I can fully sympathize with D'Abrera on this point, although I do not
share his philosophical pressumptions about what science can or cannot
explain or investigate (I am agnostic on this).

There is a widespread view (to which I do not agree) that evolution will
not take place in any consistent way without selection, and certainly
evolution texts generally to not suggest otherwise. There has, however,
been a long-standing (albeit minority) view that evolution can occur in
such a way to result in adaptations, long-term developments, and new
species, without natural selection as the driving force (if I may use a
Newtonian metaphor). 

Returning to butterfly mimics, resemblance may well be the coincidental
result of similar evolutionary trends in different species. With
development of this similarity (either within closely or distantly related
species) comes selective interactions that are also going to affect the
process, but selection is not required at the outset as a necessary causal

The above are introduced simply as a point of view, not to impose upon
those who feel differently. I am already familiar with selectionist
arguments to the contrary.

John Grehan

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