Once you can find an argument's premises and conclusion, the next question is how strongly the premises are supposed to support it. Arguments make one of two kinds of promise.
Key idea
A deductive argument claims that its conclusion must be true if its premises are true. An inductive argument claims only that its conclusion is probably true if its premises are.
Why it works
The two kinds are judged by different standards. A deductive argument promises certainty, so a single possible exception breaks it. An inductive argument promises only likelihood, so we ask how likely, and new evidence can always raise or lower that.
Worked example: Listen for the promise
"Nine of the ten students we asked enjoy chess, so most students at our school probably enjoy chess."
- The word "probably" shows the promise: likelihood, not certainty.
- It also reasons from a sample to a group, a typical inductive move.
Answer: Inductive.
Worked example: Certain, from specific cases
"Ana is taller than Ben, and Ben is taller than Cam. So Ana is taller than Cam."
- If both premises are true, there is no way for the conclusion to be false.
- It goes from specific facts to another specific fact, yet it is deductive.
Answer: Deductive.
Common mistake
Using the old rule "deduction goes from general to specific, induction from specific to general." Both examples above break it. Ask instead: does the argument claim its conclusion must follow, or only that it probably does? Words like must, necessarily, probably, likely are clues.