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Clock or what???

Shane McKee shane at reservoir.win-uk.net
Tue Jul 18 09:41:21 EST 1995

In article <3u9lff$t7a at studium.student.umu.se>,
 Ludvig Mortberg (Agneta.Guillemot at historia.umu.se) writes:

>   Is there a clock or not? People seem to back one step every time
>they are confronted with arguments against the clock theory. According
>to someone it's not even a theory anylonger. There seems to be no way
>to get hold of what the clock is about, and no way of refuting the
>theory if it's still a theory. 

I brought up in a previous post the usage of the word theory. This
is VERY IMPORTANT!! (sorry for yelling, but it is.) "Theory" can
be used in the sense: "I have a theory that the moon is made of
green cheese", and also in the sense: "I spent a long time
studying the theory of medicine."

In the former sense, "theory" roughly means "hypothesis". In the
latter sense it does NOT! It means the understanding behind the
practice of, eg, medicine. Thus in the term "The theory of the
molecular clock", theory refers to the understanding behind the
application of methods to deduce a molecular clock. The "theory of
evolution" does NOT not not (!!!) mean that evolution per se is a
hypothesis, but refers to the scientific principles underlying an
understanding of evolution.

This distinction is fundamental, and needs to be grasped before
any progress can be made on this thread.

>What is this? Can the molecular clock be used to anything at all? Do
>mutations occur in proteins in a steady fashion so that species
>gradually mutate away from each other? This was the original claim by
>Linus Pauling and Emile Zuckerkandl, wasn't it? 

It was an assumption built into their model - part of the "theory"
of their model, if you like. It does not necessarily have to be
absolutely true in all (or any) cases for the data to be useful in
another model, with a slightly different "theory". 

>Further, if someone
>asks a crucial question about the clock, there's always some scientist
>that refer to some computer simulation that's supposed to show there
>is a clock, and that no mortal can understand. Something isn't right

Yep. It's called belief. If we "believe" in a molecular clock,
we're in trouble. We do however, have data, and from that data can
draw inferences. We can be pretty damn sure of our inferences
without elevating them to the level of credo. That's what being a
scientist is all about. If you believe something, you probably
haven't thought about it enough 

Hope that clears up a few misunderstandings/language problems.

All the best,

Shane McKee (JHO, RVH, Belfast)  | /      Art becomes science when
Shane at reservoir.win-uk.net     --O--    you start trying to figure
AGACTGCGCTTGCTTTACACATTTCTTCTC / |  out what the heck you're doing

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