Logic / Unit 6 Logic 257 short lesson, about 20 seconds
Constants and Variables
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The idea
Constants (a, b, c…) name specific individuals; variables (x, y, z) range over individuals without naming any.
In practice
"s" can name Socrates. "x" names no one — it's a placeholder awaiting quantification.
Where people slip
The constant/variable distinction carries the whole system. Blur it and video 268's restrictions will find you.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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