Validity Is About Form, Not Truth
This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.
State
Validity depends on the argument's structure, not on whether its statements are actually true.
Show
"All fish fly; whales are fish; so whales fly." Every statement false — form perfectly valid.
Watch for
This is the single most common confusion in the entire subject. Sit with it.