PhilosophyIdeas
.com Database

Current Total Ideas:
19,014

home

back
structure for 'Formal Logic'

alphabetical list of themes

expand these ideas
4. Formal Logic / B. Propositional Logic PL / 4. Soundness of PL
[any formula which has a proof is a valid formula]
2 ideas
9536
If any of the nine rules of propositional logic are applied to tautologies, the result is a tautology
[Lemmon]
9543
The rules preserve validity from the axioms, so no thesis negates any other thesis
[Hughes/Cresswell]