Positivism vs Realism

[James Francis Lyons-Weiler]

that). Tell me, have you sampled published morphological datasets to
determine what percentage are reporting insignificant conguence, by
your standard? I would be very interested to know the results of
that.

        No, I haven't - because I don't know what the result would
        mean.  The test is designed for the specific case, one
        matrix at a time.  I have found published morphological
        data sets for which the test reveals sources of incongruence,
        including long edges, but I don't find the number of
        instances a very interesting question.  It could be high,
        or low.  A question you didn't ask that I find more
        interesting is how many morphological data sets can I find
        for which the application of the tests improves the
        degree of congruence by pinpointing sources of noise -
        but that work is underway.  The second question is more
        interesting because congruence (I prefer phylogenetic
        signal) is not an all-or nothing attribute of a matrix.
        It may be present, but masked in various ways (like
        misleading data from a few taxa).  So, when I have found
        morphological data "without signal", the next question
        is "why" and then "how do I uncover the signal that might
        be present".  That becomes an issue of taxon and character
        sampling.  We can't expect all regimes of character
        and taxon sampling to yield matrices that are not misleading.

        I think that will be my focus from now on.  I seem to
        get a rise out of people if I say

        We can't expect all regimes of character
        and taxon sampling to yield matrices that are not misleading
        to <insert your favorite criterion here>

        But if I say

        We can't expect all regimes of character
        and taxon sampling to yield matrices that are not misleading

        Then I don't raise the hackles of the pious.

        James LW

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