logic; BCF (going gets tough)

["Ken Kinman" <kinman@hotmail.com>]

Philidor,
    In some ways I think you are unnecessarily self-inflicting a sort of 
mental pain by trying to logically analyze such questions and agonizing over 
each and every step.  Especially over abstractions like circles and 
infinity.  Using similar logic you could perhaps show that circles cannot 
exist, and therefore it is rather illogical to even debate measuring the 
area of something that doesn't exist.
    In cladistically analyzing groups of organisms, I use the concept of 
sister groups.  However, I do not think that sister groups actually exist.  
They are an abstraction that Hennig found to be methodologically useful (and 
pointing this out often helps students who otherwise find cladistic analysis 
illogical).  I avoid ever getting into arguments of logic with those who 
insist that sister groups actually do exist (I figure it would be a waste of 
time), but I would think it would be much easier to argue against the 
reality of sister species than against the reality of circles (or even 
whether the areas they enclose can be determined, assuming they do "exist").
    I use sister groups and calculus as useful methodologies, but I do not 
waste much time philosophically (especially logically) trying to justify it. 
 Otherwise you really do risk miss seeing the forest for the trees (yes, I 
know I overuse such cliches).
    Not that I think cladistic analysis is anywhere nearly as precise as 
calculus (for those who think my analogy is stretching it).  On the 
contrary, cladistic analysis (however useful it may be when used properly) 
is quite vulnerable to subjective decisions, circular reasoning, and other 
inherent drawbacks.
   I think it is still up in the air whether or not current dinosaur 
cladograms are flawed on the question of whether dinosaurs came first (still 
widely embraced) or birds came first (BCF).  That is another reason I oppose 
using strictly cladistic classifications, but I also believe that cladistic 
analysis will ultimately decide the question once enough data is available.  
So I use "logic" in trying to detect possible circular reasoning, but 
pushing logic too far seems to be a sort of mental self-torture.  All things 
in moderation.
                      -----Ken Kinman
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philidor11 wrote:
> I've argued with a friend .... that the
> area of a circle cannot be determined.  The formula assumes squares small
> enough to fit the outline of a curved surface, and that can't happen until
> the squares become points, in which case they can't measure...  And so many
> functions don't work until you reach infinity, and by definition infinity
> can never be reached....
but I break arguments into single
> steps to worry each one.  For you and my grandfather calculus may be
> enjoyably self-consistent and self-evident, but for me and a few other
> people the inherent assumptions are downright painful.
> Ok?
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