From:	Dave Sherohman <esper@*****.IMA.UMN.EDU>
Subject:	Bad logic
Date:	Wed, 14 Apr 1993 17:16:30 -0500

>up alittle? I can't even tell which of my suppositions your disputing. If my
>logic is flawed (an my last post was not meant to be gospel, just theory) then
>I would like to know where. And while your at it do you have any views on
>
>Here's a little good logic:
> All fish have fins and gills.
> Sharks have fins and gills.
> Therefore, sharks are fish!

Sorry, Nightstalker, but that logic is as bad as the 'proof' that sharks are
trout, it just happens to true.

This is actual good logic:
All things with fins and gills are fish.
Sharks have fins and gills.
Therefore, sharks are fish!

Your supposedly good logic is (logically speaking) equivalent to the bad logic
you attempted to refute. You just changed a word such that a logically flawed
argument produced a true conclusion.

Bad logic:
All X have Y.
Z has Y.
Therefore, Z is X.

This may be true or false, depending on the values of X, Y, and Z.

Good logic:
All X have Y.
Z is an X.
Therefore, Z has Y.

This may also be true of false, but if the first two lines are true, then line
3 _must_ be true. As was demonstrated with the "sharks are trout" example, the
"bad logic" form can have true statements in lines 1 and 2, but produce a
false conclusion on line 3.

For the sake of topicality, I really don't think it matters whether spirits are
slaves or not; people have their own opinions, will act accordingly, and will
probably not be convinced that the other view is correct. It's basically a
religious/political position.

esper@***.umn.edu