Re: Help with a problem

"George Dance" <georgedance04@xxxxxxxx> writes:

> Are you saying that none of the systems based on that 'approach',
> except for Gentzen's NJ and NK, should be called "natural deduction".

In the US, the term "natural deduction" is indeed commonly used in a
sense that includes Copi's system. This is just a fact of usage, and
thus uncontroversial. The essential point concerns the distinction
between Copi's hodgepodge collection of rules and the accompanying set
of problems of constructing derivations, which many may find
entertaining and rewarding, and natural deduction in Gentzen's sense,
which is concerned with the logical analysis of mathematical
reasoning.
.

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