Archaeopterygid bird from China
Don.Colless at CSIRO.AU
Don.Colless at CSIRO.AU
Thu Mar 31 17:41:29 CST 2005
This thread has illustrated the taxonomists' (usually cladists') practice of hiding behind Karl Popper, using the term "hypothesis" to cover everything from an outrageous guess to a pretty credible conclusion. John G. misses the point that under Popperismus, the origin of the hypothesis is irrelevant; all that matters is whether it is confirmed or rejected. I think most scientists will regard this as nonsense; we couldn't even start to test the vast array of POSSIBLE hypotheses. Philosophers (e.g., Hilary Putnam) have examined the point. Peter Lupton provides a succint statement: we apply an "epistemic filter" to sort out a set of reasonably testable hypotheses. He does this in arguing for "inference to the best conclusion"; but it applies all over. It's worth bearing that in mind next time you accept a maximum likelihood solution, when the winner has a probablity of 0.00001, over the next best with 0.000009.
Howsomever, I must agree that finding a swag of primitive birds in China and only one outside China remains a reasonable base for the hypothesis that the damn' things started out in China. It's the only evidence we have. Of course they might in fact have begun in Antarctica - or Mars - but the fact that an hypothesis MIGHT be wrong is no reason for not testing it, if we don't have any more promising. But, by the same token, the mere fact that it IS an hypothesis doesn't mean it must stay on the books forever. What we keep are CREDIBLE hypotheses.
Much of what I've written above reflects my irritation when folk produce, say, a cladogram, and then go on about their "phylogenetic hypothesis", when it is perfectly clear that they are accepting it as gospel, and they continue to derive all sorts of RESULTS about, say, biogeography. There's an old term "mealy-mouthed" that I'm inclined to apply.
Of course, I'm a grumpy old man.
Div of Entomology, CSIRO,
GPO Box 1700,
Email: don.colless at csiro.au
Tuz li munz est miens envirun
From: Taxacom Discussion List on behalf of Richard Pyle
Sent: Thu 3/31/2005 2:33 PM
To: TAXACOM at LISTSERV.NHM.KU.EDU
Subject: Re: Archaeopterygid bird from China
> While I do agree with you that the location of oldest
> fossil is not "necessarily" near the origin of a family, I agree
> with Dick that an Asian origin for Archaeopterygidae is presently
> the best hypothesis.
Although I agree with most of the points in Richard Zander's concurrent
post, I think it's important to remember that "best" is a relative term. I
can't help but believe there is some sort of threshold where the "best"
hypothesis among several is every bit as indistinguishable from "crap" as
the worst hypothesis. Something with a 2% probability of being correct is
twice as likely as something with a 1% probability of being correct...but
neither serves as a very useful working hypothesis. I think it all depends
on the particulars of each case.
I don't know the details in this case, but I have to say that I find John
Grehan's position, while perhaps a bit extreme [e.g., "Everything else (I
would submit) is largely, if not wholly, a fanciful conjecture masquerading
as science..."], to be the "best" perspective among several.... :-)
Shitfing gears a bit, this same point is largely why simply knowing that a
particular phylogenetic arrangement represents the "most parsimonious" tree
tells me very little about how much faith I should put in its approximation
to reality (e.g., whether it's worth disrupting nomenclatural stability
Richard L. Pyle, PhD
Ichthyology, Bishop Museum
1525 Bernice St., Honolulu, HI 96817
Ph: (808)848-4115, Fax: (808)847-8252
email: deepreef at bishopmuseum.org
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