Helmut,
The distinction between intesion and extension is
important for every version of logic since antiquity. The oldest example
is "rational animal" vs. "featherless biped" -- those
are two terms with different intensions, but the same extension. Diogenes
the Cynic plucked a chicken and thr
Jon, John,
just a thought: Might it be, that in classical mathematics and logic there is not distinguished between intension and extension, and in intuitionistic logic there is? For example, "NOT (A AND NOT B)" is an extensionistic proposition, or the extension of the relation, but "IF A THEN B
