PP264 Lecture Notes - First-Order Logic, Pegasus, Null Set
Document Summary
Syllogism --> premise 1, premise 2, then conclusion (structure). Truth of the premises leads to the validity of the conclusion. (p1) if i go to the store then i will have cigarettes. If you find the conclusion to be false then the argument is deductively invalid. (p1) nancy is taller than scott (p2) scott is taller than mohammed (c) nancy is taller than mohammed. --> aristotelian logic is limited to categories but not relations such as these. -> you need a new logic to account for this type of inference (relations) Frege: predicate logic (second order predicate logic) Russell & whitehead --> definitive and used in mathematics. Numbers are logical objects where you find in sets. Logisism: logical development in order to figure how mathematics works (which is a form of logic) Plato"s beard: every word in every sentence has to refer. 2 to something if that sentence is meaningful. Pegasus subsists and does not exist (not spacio- temporal)