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Imagination / abstract / Berkeley: the idea of a triangle must be neither acute nor stump nor rectangular etc. - then it’s not a triangle - so there are no abstract ideas - VsBerkeley: merges the problem with the abstraction: how is it possible that a one can have a relation to a class or species? (General / Special) - there can be no similarity between giving something that is an idea and something that is no idea - a perception cannot reflect something that is external to perception.
I Breidert Berkeley: Wahrnnehmung und Wirklichkeit, aus Speck(Hg) Grundprobleme der gr. Philosophen, Göttingen (UTB) 1997