Re: [ontolog-forum] Truth

[Chris Menzel <chris.menzel@xxxxxxxxx>]

On Tue, Jul 10, 2012 at 2:36 PM, Matthew West <dr.matthew.west@xxxxxxxxx> wrote:

Dear Doug,

> However, one would stretch to come up with what "an instance of the planet
> Venus" would be.

MW: There is no problem with singleton classes. It is trivial to construct a
class that has just the planet Venus as an instance.

These seems orthogonal to Doug's point which, I take it, is that the planet Venus is not itself a class. AFAICS he didn't say anything one way or the other about singleton classes.

 

Why you would want such a class is another thing.

People define classes all the time without knowing exactly how many instances the class has. In some cases, it might turn out that there is only one (e.g., {x : x is a solar planet with an orbital period between 150 and 250 earth days} = {Venus}).

-chris

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