Cladistic hypotheses

[John Grehan]

I'll have to look this article up as I might be able to use it in an article I am writing on the contradiction of orangutan morphology and chimpanzee sequences similarities with humans. Most biologists take the postion that the sequence simiarlity hypothesis is not only a test of the morphology, but also a falsification of morphology. I would only add that I would use the term corroborate rather than confirm, but its much the same thing. Where hypotheses are incongruent one has a research anomaly, which is really a research opportunity rather than the closed door as it is treated in human origins research.
 
John Grehan

________________________________

From: Taxacom Discussion List on behalf of Don.Colless at CSIRO.AU
Sent: Wed 11/23/2005 10:58 PM
To: TAXACOM at LISTSERV.NHM.KU.EDU
Subject: Re: [TAXACOM] Cladistic hypotheses



Bravo, Kirk! In Sys. Zool. 31: 100-104 (1982!) I pointed out that "testing" one hypothesis with another is nonsense. At best it can only CONFIRM, but never REFUTE; as I wrote then "Ultimately one is just counting the score: the number of consistent hypotheses". Maybe, though, one can use the "Inference to the Best Explanation" model.

Don Colless,
Div of Entomology, CSIRO,
GPO Box 1700,
Canberra. 2601.
Email: don.colless at csiro.au
Tuz li munz est miens envirun


-----Original Message-----
From:   Taxacom Discussion List on behalf of J. Kirk Fitzhugh
Sent:   Thu 11/24/2005 4:39 AM
To:     TAXACOM at LISTSERV.NHM.KU.EDU
Cc:    
Subject:             Re: Cladistic hypotheses
At 10:17 AM 11/23/2005 -1000, you wrote:
>I didn't entirely understand Kirk's message that prompted this, but as I
>see it, you test the cladogram by running an analysis and determining if
>it is the best one available according to whatever criteria (parsimony,
>ML, Bayesian, etc.) you are using.  Of course this is all automated so
>that the "hypotheses" are generated automatically.  The only thing that
>seems unusual (in terms of deviating from typical scientific theory) is
>that a hypothesis (i.e. cladogram) can't really be falsified on its own
>but only when you find another one that has better support.

Unfortunately, there is nothing within the inference of cladograms,
regardless of what software one uses or mental inclination one has, that
has anything at all to do with testing.  The long-standing notion that one
cladogram can test/falsify another cladogram is mistaken.  One cladogram
based on data set a+b+c cannot be evaluated against a cladogram based on
data set a+b+c+d (or even mutually exclusive data sets).  The two
hypotheses stand independent of one another as entirely different causal
explanations for different sets of causal questions.

Kirk

-----------------------------------------------------
J. Kirk Fitzhugh, Ph.D.
Curator of Polychaetes
Invertebrate Zoology Section
Research & Collections Branch
Los Angeles County Museum of Natural History
900 Exposition Blvd
Los Angeles CA 90007

Phone:   213-763-3233
FAX:     213-746-2999
e-mail:  kfitzhug at nhm.org
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