Failure of Traditional classification propositions

"All unicorns are white" — true or false? The traditional A/E/I/O scheme has no comfortable answer, because it was built assuming the subject class actually has members. The moment logicians started asking about empty classes, relations, and quantities other than ‘all’ and ‘some’, the tidy fourfold scheme started to creak, and this topic is the list of exactly where it breaks.

In two minutes

The traditional fourfold classification of propositions, though useful, fails in several respects: it assumes existential import that modern logic rejects, it cannot comfortably classify singular or relational propositions, it recognises only two quantifiers (all, some) though ordinary language uses many, and it has no way of handling compound or hypothetical propositions at all.

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