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Re: [ontolog-forum] Endurantism and Perdurantism - Re: Some Comments on

To: ontolog-forum@xxxxxxxxxxxxxxxx
From: John F Sowa <sowa@xxxxxxxxxxx>
Date: Fri, 03 Apr 2015 13:24:56 -0400
Message-id: <551ECCE8.70705@xxxxxxxxxxx>
Dear Matthew,    (01)

We agree about the problems.  I have been trying to clarify Pat's
point about using a logic that lets you relax the constraints.
In many cases, that can be helpful.  But it's not magic.    (02)

> With a less restricted logic, you can say anything you like.
> If it causes a contradiction, you just delete one or more axioms
> -- in this case, the axiom that a moving car shall have a driver.    (03)

> Sure. But there is also a problem that sometimes definitions just are
> inconsistent. So in the UK 3 wheeled cars were (at one time at least)
> classified as motorcycles with sidecars. I doubt many other countries
> defined car to exclude 3 wheelers.    (04)

Any language that lets you say (P and not P) can state a contradiction.    (05)

But some languages (logics) are so restrictive that they make it
impossible to express some true sentences.  In some strictly typed
logics, you can't say "The number 7 is not an elephant."    (06)

That's a true statement that cannot be expressed.  A more subtle
example is "No object is a process."  Sometimes you might want
to say that something could be either or both.    (07)

John    (08)

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