Re: Help with a problem

"George Dance" <georgedance04@xxxxxxxx> writes:

> If one's aim is to use nd to formalize the inferences of informal
> reasoning, then a system like Copi's would work best.

A bizarre notion. The reasoning from "If r is positive, r is in E"
to "If r is positive and r is in S, r is in E" in the "elegant
and simple" derivation given by an unfortunate expert on Copi's system
goes

If r is positive, r is in E. So either if r is positive, r is in E,
or r is not in S. So either r is not in S
or if r is positive, r is in E. So if r is in S, if
r is positive, r is in E. So if r is in S and r is
positive, r is in E. So if r is positive and r is in S,
r is in E.

This bears no resemblance to any informal reasoning from "If r is
positive, r is in E" to "If r is positive and r is in S, r is in E"
found in nature.

.

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