Re: more on tautology

Thomas Clarke (
13 Nov 1995 02:59:12 GMT

In article <47q8rl$> Alex Duncan <> writes:
>In article <47p3qk$> Tom Clarke,
> writes:

>>>Can you say "tautology"?

>>I think you are taking advantage. A loaded syllogism is a dangerous
>>thing in amateur hands.

>>If AAT had been replaced by "Elaine Morgan's writings" then
>>there would have been no tautology.

>I am not taking advantage, and the argument remains tautological no
>matter what I replace the term "AAT" with. The point is that AAH (in my
>understanding) is seeking to demonstrate that hairless skin, subcutaneous
>fat and tear shedding are aquatic adaptations. Thus, these features
>can't be used in an argument to demonstrate that another animal has
>aquatic ancestors without the argument becoming tautological. If you do
>so, what you're trying to prove is assumed at the start.

OK, the AAH is seeking to demonstrate that hairless, fat skin et al
are the result of an aquatic episode.

This argument or demonstration is either valid or invalid.
The form of the argument is independent of what species it is
applied to. It may even be true that one land species with these
characteristics had an aquatic ancestor and another did not.
(In this case the general argument would of course be invalidated.)

Now you are claiming that AAHists argue that since elephants
have the hairless fat skin et al, that they must have aquatic
ancestors. And further you claim that they they argue that
since elephants have an aquatic ancestor that this is evidence
that any mammal with hairless, fatty skin et al must have an
aquatic ancestor. This would indeed be circular, tautological.

What I read in Ms. Morgan's books is that she believes (rightly
or wrongly) that there is INDEPENDENT paleontological evidence
that elephants had an aquatic ancestor. Since she holds this
belief (rightly or wrongly) the form of her argument is not
a tautology.
[The argument may be wrong, but I address here only the
question of whether it is a tautology]

> It is very
>similar to the argument:

>1) god made everything

>2) since everything exists, it proves the existence of god.

Had to get some creationist digs in didn't you?

Well, I can't resist let me recast what I said above in your
theological terms.

A) hypothesis: planets with intelligence were created by a god,

B) radio signals from such a creation event have been detected,
{god to lucifer: "Give that asteroid a nudge, it's going to miss
the third planet."}

C) Earth has intelligent life therefore it was created by a god.

The observation in B) of course makes the A,B,C argument scientific.
[No such observations have been made, nor are likely to be made,
but I again emphasize that I am talking about the form of the argument]

Sometimes I think science is just too young, its chief
opponent creationism not left far enough behind, that arguments
that assume special conditions cannot yet be accepted, even if
they provide the best explanation. Many planetologists cannot
accept a catastrophic origin of Venus' present crust, there
was a great deal of resistance to the idea that an asteroid
impact marked the end of the Cretaceouse, there is suspicion
of the impact theory of lunar origin because it is "catastrophic",
etc. etc.

Tom Clarke