Logic / Unit 3 Logic 096 short lesson, about 20 seconds
The Venn Test for Validity
Captions available
The idea
Diagram both premises — and only the premises — on three overlapping circles. If the conclusion already appears in the diagram, the syllogism is valid.
In practice
Valid means the premises drew the conclusion for you.
Where people slip
Diagram universal premises before particular ones; shading determines where an X can land.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Something wrong in this lesson? Flag it · Sources for Logic