A friend forwards you a message: "Some customers got a full refund. Is yours on the way? Reply now!" Three sentences, and only one of them could be true or false. That one promises less than it seems to. It says at least one customer got a refund. It doesn't say you will, and it doesn't even say that most people did. Reading a message like that carefully is a skill, and this chapter builds it from the ground up.
The picture to carry through the chapter is a fact-checker with two rubber stamps, TRUE and FALSE. Section 1 asks which sentences can be stamped at all. Statements can. Questions, commands, and exclamations can't. A statement nobody can check yet still gets a stamp. We just don't know which one.
Section 2 asks what a stamp depends on: only what the words promise, not what a listener guesses. "Some" means at least one. "All" never promises that anything exists. "Only" limits in one direction. And "or" stays true when both parts hold, unless the sentence says otherwise.
Section 3 adds a second question. Besides "is it true?", ask "could it have been true?" Imagining one specific way the world could be, and checking a claim against it, turns out to be the sharpest test for a general claim in the whole course.
Section 4 is short. It explains how the practice in every later chapter is built, and the habit of answering with a reason.
By the end, the message about refunds should read differently. You'll see one statement, a question, and a command, and you'll know exactly what the one statement promised.