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From: jacob@hpfclo.UUCP (jacob)
Newsgroups: net.nlang
Subject: Re: All men...
Message-ID: <53300001@hpfclo.UUCP>
Date: Tue, 7-Aug-84 11:52:00 EDT
Article-I.D.: hpfclo.53300001
Posted: Tue Aug  7 11:52:00 1984
Date-Received: Mon, 6-Aug-84 01:07:00 EDT
References: <237@siemens.UUCP>
Organization: Hewlett-Packard - Fort Collins, CO
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Nf-ID: #R:siemens:-23700:hpfclo:53300001:000:821
Nf-From: hpfclo!jacob    Aug  2 07:52:00 1984

It might be "a perfectly acceptable statement," but it is
an invalid deduction no matter which way to put it.  Let's
formalize the first statement ("A" = "for all", "E" = there exists):

(A x)(Man(x) -> Die(x)) --> (E y)(Man(y) ^ Female(y))

Do you still claim it is a tautology?  Same goes for the second, less
ambiguous statement:

(A x)(Human(x) -> Die(x)) --> (E y)(Man(y) ^ Female(y))

or, for that matter:

(A x)(Human(x) -> Die(x)) --> (E y)(Human(y) ^ Female(y))

None of the above, independently, are true, so they are not valid deductions.
The only reason the second formulation "feels better" is that we rely on
knowledge that there are female humans.  But that is the conclusion of
the statement, so if we accept it as a premise, we don't even need to know
if they die or not.

Jacob Gore
ihnp4!hpfcla!jacob