Re: Don't Constrain my Laws, Danny!

Cameron Laird (claird@STARBASE.NEOSOFT.COM)
Thu, 14 Sep 1995 06:38:39 -0500

Logic sometimes employs the labels of "extension" and
"intension" for categories analogous to these. Example:
we define "monotremes" as

taxon which includes platypuses and

by extension and

oviparous mammals

by intension. Lots of people working with biology *want*
definitions by intension, because, as Danny hints in part
of what I elided, formal definitions permit calculation;
they encourage symbolic manipulation which holds the pro-
mise of significance back in the biologic realm. Even if
we don't wish to commit ourselves to the philosophical
conclusion of Ghiselin et al., it's important to realize
in our daily thought how problematic are such notions as
"species". "Species" is a good idea, a useful organizing
principle, perhaps even a deep one, but we certainly need
to be wary about asking it to do identical work for

canids (domestication)
ants (haplodiploid sociality)
anthropoids (so close to home--and
domesticated with a vengeance)
hybridizing, parthogenetic lizards
plants (LOADS of variations here,
including obligate parasitism,
alternating generations, ...)
some "normal" species--Eurasian
mustelids, say

Cameron Laird +1 713 267 7966
+1 713 996 8546 FAX