Single Idea 17745

[catalogued under 4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / d. Universal quantifier ∀]

Full Idea

'All A's are B's' meant for Frege that the concept A implies the concept B, or that to be A implies also to be B. Moreover this applies to arbitrary x which happens to be A.

Gist of Idea

For Frege, 'All A's are B's' means that the concept A implies the concept B

Source

report of Gottlob Frege (Begriffsschrift [1879]) by Michal Walicki - Introduction to Mathematical Logic History D.2

Book Reference

Walicki,Michal: 'Introduction to Mathematical Logic' [World Scientific 2012], p.23


A Reaction

This seems to hit the renate/cordate problem. If all creatures with hearts also have kidneys, does that mean that being enhearted logically implies being kidneyfied? If all chimps are hairy, is that a logical requirement? Is inclusion implication?