Every argument has two kinds of parts. To read one well, you first sort its sentences into the claim being argued for and the reasons for it.
Key idea
The conclusion is what the speaker wants you to believe. The premises are the reasons offered for it. Find the conclusion first; then the premises are the sentences that support it.
Why it works
A sentence is a premise or a conclusion because of the job it does in this argument, not because of where it sits. The same claim, "We need to leave by seven," can be a conclusion in one argument and a premise in another ("We need to leave by seven, so set an alarm").
Worked example: Conclusion in the middle
"The lights are on at Ava's house. Ava must be home. Besides, her bike is in the driveway."
- Ask: what does the speaker want me to believe? That Ava is home.
- The lights and the bike are offered as reasons for that.
- So the conclusion is the middle sentence; the other two are premises.
Answer: Conclusion: "Ava must be home." Premises: the lights are on; the bike is in the driveway.
Worked example: Ask "why should I believe that?"
"The library's history books are all checked out. The report is due Friday. So Kai had better start looking online."
- Try each sentence as the conclusion and ask "Why should I believe that?"
- "Why should Kai look online?" Because the books are out and the report is due soon. The other sentences answer it.
- Nothing answers "Why are the books checked out?" in the passage, so that sentence is a premise.
Answer: Conclusion: "Kai had better start looking online."
Common mistake
Assuming the first sentence is a premise and the last one is the conclusion. Writers often lead with the conclusion. Test each candidate: the conclusion is the one the others are reasons for.