 But this presupposition is not part of the content of the expression, and hence (4a) does not entail existence, or the negation of (4a) would not be (4b) but Kepler did not die in misery or the name “Kepler” has no reference, an outcome Frege seems to have taken as an absurdity but one that prefigures the later emergence of a presupposition-cancelling external or exclusion negation.