3TA (was Human and ape phylogeny)

[Kirk Fitzhugh]

Actually, no "test" has been performed. The first inference, leading to
(A(B,C)), is entirely distinct from the inference leading to (A(B,C)).
These are different inferences derived from different sets of premises. One
has nothing to do with the other except to show that one has modified a
previous inference to take into consideration additional observations in
need of explanation in the same context as the original observations - this
is nothing more than abiding by the requirement of total evidence. One
might claim that they deduced, as consequences of (A(B,C)), additional
synapomorphies under the guise of a Popperian test. Unfortunately, such a
deduction is not a valid test since (A(B,C)) will account for those new
data no matter what. What are of relevance as tests are consequences of the
causal events claimed by (A(B,C)). Such consequences must be of a class of
effects independent from the class of effects, i.e., characters, the
hypothesis is intended to address.

Kirk

At 01:19 PM 4/9/03 -0500, you wrote:
>A phenetic classification is a hypothesis about natural
>relationships.  What are
>the relationships among A ,B and C?  Our initial data set yields (A(B,C)).  We
>"discover" a new set of characters that we believe will help clarify the
>relationships.  We include these with our initial data and the answer is
>(A(B,C)).
>Thus, our initial hypothesis has been tested against the new information
>and has
>been found to be consistent with the new information (or, at the least,
>the new set
>of characters did not have a strong enough signal to alter the
>result).  Of course,
>one could argue that the 250 characters in our first data set completely
>swamped
>the signal in the 10 newly discovered characters, but that's another matter
>entirely.  The second result is based on total evidence and we have no
>reason to
>question our hypothesis that (B,C) is a natural group with respect to A.
>
>Cheers,
>
>Dick