The Corner

A Logician Writes In

Thus: 

C’mon, Derb, ‘a null set’ is perfectly fine from the point of view of a regular mathematician, it is only the fussy logicians who insist on ‘the null set’ because the axioms of Extensionality and Foundation produce a set-theoretic universe with nice METAmathematical properties.

REAL mathematicians work with the integers as atoms (viz. Kronecker) and do not regard 3 as { {}, {{}}, { {}, {{}} } }. They also do not regard (x,y) as { {x}, {x,y} }.

I’ll tell you, it means an awful lot to have a President who knows the basics of logic. Romney clearly does, Giuliani does, and Fred Thompson obviously does. This makes them capable of making progress with public opinion against the MSM headwind that overwhelms ordinary politicians.

From the point of view of a professionally trained logician, I can tell you that the best logician in public life today, by a significant margin, is Antonin Scalia. Reading his opinions produces some of the same enjoyment that can be obtained from a fine and rigorous mathematical exposition.

Yeah, yeah.  Though in fairness to Romney, he may have been trying to resurrect the Ramified Theory of Types, in which, IMS, “a null set” is permissible.

John Derbyshire — Mr. Derbyshire is a former contributing editor of National Review.
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