Modus ponens

Modus ponens is a fancy way of saying if A then B and A is true, then B MUST be true. It is a way of making sure that our reasoning is logical.

Let's say there are two kids, Jack and Jill, who live next door to each other. Jack says that if it rains, then Jill will stay inside to play. It is raining outside, so modus ponens is telling us that Jill must stay inside to play!