One way to clear up ambiguity and vagueness is to define your words. But definitions do different jobs, and each job is judged differently.
Key idea
A lexical definition reports how a word is already used. A stipulative definition gives a new word, or a new meaning, for a purpose. A precising definition sharpens a vague word. A persuasive definition slants a word to sway feelings.
Why it works
A lexical definition is a report, so it can be accurate or mistaken. A stipulative one is a choice ("let's call this a frogurt bar"), so it can be clear or unclear but not false. A precising one must fit the old meaning while drawing a line. A persuasive one hides an argument inside a definition.
| Kind | Example | Can it be false? |
|---|---|---|
| Lexical | "Triangle" means a closed shape with three straight sides. | Yes, if it misreports usage |
| Stipulative | In our club, a "zoomer" is anyone who solves a puzzle in under a minute. | No |
| Precising | For this contest, "tall" means 150 cm or more. | It can fit badly |
| Persuasive | "Homework" means a cruel waste of evenings. | It slants rather than reports |
Worked example: Name the kind
"For the race rules, 'late' means arriving more than five minutes after the start."
- "Late" already has a meaning, but a fuzzy one.
- This definition draws a sharp line for one purpose.
Answer: Precising.
Worked example: Report or choice?
"Let's call the new apple-and-yogurt snack a 'frogurt bar.'" Can this be false?
- It names something new; no one used "frogurt bar" for it before.
- It is a choice, not a report about usage.
Answer: Stipulative, so it cannot be false (only clear or unclear).
Common mistake
Judging a stipulative definition as true or false. A new name for a new thing cannot be wrong, though it can be confusing. Ask first what job the definition is doing.