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- n. Alternative form of equipollence.
Sorry, no etymologies found.
It has its dangers, as has been fully granted; the notion of this sort of equipollency in man's modes of activity may lead to moral relaxation, what we do not make our one thing needful we may come to treat not  enough as if it were needful, though it is indeed very needful and at the same time very hard.
All the cases mentioned in books of Logic as examples of equipollency or equivalence of propositions, are of this nature.
In a manual for young students, it would be proper to dwell at greater length on the conversion and equipollency of propositions.