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From: colonel@gloria.UUCP (Col. G. L. Sicherman)
Newsgroups: net.singles
Subject: Re: Logic
Message-ID: <920@gloria.UUCP>
Date: Fri, 12-Jul-85 11:47:05 EDT
Article-I.D.: gloria.920
Posted: Fri Jul 12 11:47:05 1985
Date-Received: Mon, 15-Jul-85 00:44:12 EDT
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["You do not know that I do not know that you do not know you're right."]

> EVERYONE should know how to do proofs with quantifiers!  For one thing, it's
> taught in the introductory CS math courses most places, and for another,
> it'll probably be on that test you're going to take, if it's any good...
> I mean, everyone should know that
> 	"For all x, y"
> is the same as
> 	"It is not the case that there exists an x such that not(y)".
> 
> Among other things, not knowing basic principles of logic like that makes
> it hard to argue coherently in everyday discourse.

Curiously, professional logicians like Raymond Smullyan take the
opposite stand: that logic is a game, and its usefulness is limited
to reducing knowledge.  I recall one of his examples of how formal
logic fails in ordinary discourse:

			"Good Food is not Cheap
			 Cheap Food is not Good"

Should the restorateur have omitted one of the sentences on this signboard?

I notice that the weakest arguers on the net are those who cling to logic.
-- 
Col. G. L. Sicherman
UU: ...{rocksvax|decvax}!sunybcs!colonel
CS: colonel@buffalo-cs
BI: csdsicher@sunyabva