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Intension/classes/quantities/Frege/Russell/WittgensteinVsRussell/WittgensteinVsFrege: both believed they could deal with the classes intensionally because they thought they could turn a list into a property, a function.
Intension/extension/Mathematics/Wittgenstein: in everyday language intension and extension are not interchangeable - E.g. I hate the man in the chair - I hate Mr. Schmitz - on the other hand in mathematics: here, there is no difference between "the roots of the equation x² + 2x + 1 = 0 and "2"- in contrast difference: counting bodies ((s) extension, also writing down) is something different than to determine them with a law ((s) intension) - Wittgenstein: law and extension are completely different - ((s) Physics).
Elementary PropositionVsIntension - (protection of formal logic) - intension/meaning/Tractatus/Flor: irrelevant - it is always about extension.
Vorlesungen 1930-35 Frankfurt 1989
Das Blaue Buch - Eine Philosophische Betrachtung Frankfurt 1984
Tractatus Logico Philosophicus Frankfurt/M 1960