Logic / Unit 6 Logic 256 short lesson, about 20 seconds
Why Propositional Logic Isn't Enough
Captions available
The idea
"All humans are mortal; Socrates is human; so Socrates is mortal" symbolizes as p, q ∴ r — invalid propositionally. The validity lives inside the statements.
In practice
Propositional logic sees atoms; this argument's engine is subatomic.
Where people slip
Predicate logic doesn't replace Units 4–5 — it extends them downward, keeping every rule.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Unlocks
Something wrong in this lesson? Flag it · Sources for Logic