Lesson 1.1 — AND

The Word

You use AND every day. It's the smallest, plainest word for putting two things together.

"Mom said I can have cake AND ice cream."

When your mom says this, what does she mean? She means BOTH things — cake AND ice cream. Not just cake. Not just ice cream. Both.

The whole sentence is true only when BOTH parts are true. The whole sentence is true or false even if parts of the sentence are true or false. AND is logic that you use everyday!

The Truth Test

To check whether an AND sentence is true, look at each part separately, ask whether IT is true, then put them together. Try it below — pick a truth value for each claim and watch what happens to the whole sentence.

Only one row out of four gives you a TRUE whole. AND is picky.

A Real Example

"I cleaned my room AND I did my homework."

When can your parents call this a true sentence?

• If you cleaned your room but didn't do your homework — call-out.
• If you did your homework but didn't clean your room — call-out.
• If you did neither — definitely call-out.
• If you did both — they're stuck. The sentence is true.

AND only protects you when BOTH halves hold up.

Tricky Bits

1. AND can hide in a list.

"She's tall, dark, and handsome."

That's three AND statements stacked: "She's tall AND she's dark AND she's handsome." All three have to be true.

2. Sometimes "and" means "then."

"I opened the door and walked out."

That's a sequence, not logical AND. English overloads the word. In LOGIC class, we only mean the both-true version.

Recap

• AND means BOTH must be true.
• One part false = whole sentence false.
• English has other uses of "and" (sequence, listing) — those aren't logical AND.