Most everyday arguments leave out the premise that does the real work; find it by asking what would have to be true for the stated reason to support the conclusion, say it aloud, and see whether anyone is still willing to assert it.

How to do it

1. 1Reduce the argument to its stated reason and its conclusion: "He has never run a business, so his tax proposal is unworkable."
2. 2Ask what general statement would connect them. Here: "Only people who have run businesses can design workable tax policy." That is the missing premise.
3. 3Say it aloud, neutrally, as a question: "Is the assumption that only business owners can judge tax policy?" Supplying the premise is often all the refutation that is needed, because the speaker will not defend it in that form.
4. 4Be charitable in the reconstruction. If a weaker, more plausible premise would do the job ("relevant experience makes workable proposals more likely"), supply that one, and then note that it supports a weaker conclusion.
5. 5Watch for the words that mark a gap being skated over: "surely", "obviously", "clearly", "it goes without saying", "everyone knows". Dennett's advice is to treat "surely" as an alarm indicating a claim the author hopes you will not examine.
6. 6Look also for premises hidden inside questions and descriptions ("when will the government admit its failure?"), where the assumption arrives as background and not as a claim.

When to use it

• •A conclusion feels too quick but you cannot say which statement is false.
• •An advertisement, slogan, or speech invites you to complete the thought yourself.
• •A stated reason is true, and irrelevant unless something unstated is also true.
• •A question or a description carries an assumption you have not agreed to.

Counters

Evidence and how strong it is

The observation is as old as the study of rhetoric. Aristotle called the argument with an unstated premise the enthymeme and considered it the core of persuasive speech, in part because the audience supplies the missing piece themselves and is more convinced for having done so. Modern argumentation theory treats the reconstruction of unstated premises as a central analytic task; Walton and Reed (2005) show how argument schemes can be used to identify what is missing in a disciplined way, and Walton (2008) discusses the attendant risk of attributing premises the arguer never held. Dennett (2013) offers the practical heuristic of treating "surely" and its cousins as markers of the weakest point. Research on persuasion gives indirect support for the rhetorical claim: messages that lead audiences to draw the conclusion themselves can be more persuasive among motivated, able audiences, though the broader literature finds that explicit conclusions usually persuade at least as well (O'Keefe 1997). Whether training people to articulate missing premises makes them harder to mislead has not been tested directly. Evidence strength: scholarly consensus about the analysis; untested as an intervention.

1. Walton, D., & Reed, C. A. (2005). Argumentation schemes and enthymemes. Synthese, 145(3), 339-370
   A method for identifying the unstated premises of arguments by reference to common argument schemes.
2. Walton, D. (2008). Informal Logic: A Pragmatic Approach (2nd ed.). Cambridge University Press
   The treatment of missing premises, loaded questions, and the risk of misattributing commitments when reconstructing an argument.
3. Dennett, D. C. (2013). Intuition Pumps and Other Tools for Thinking. W. W. Norton
   The "surely" operator: the heuristic that words asserting obviousness often mark an argument's weakest, least examined step.
4. Aristotle (2007). On Rhetoric: A Theory of Civic Discourse (G. A. Kennedy, Trans., 2nd ed.). Oxford University Press
   The classical account of the enthymeme as the central form of rhetorical proof.
5. O'Keefe, D. J. (1997). Standpoint explicitness and persuasive effect: A meta-analytic review of the effects of varying conclusion articulation in persuasive messages. Argumentation and Advocacy, 34(1), 1-12
   Meta-analytic evidence that messages with explicitly stated conclusions are generally at least as persuasive as those leaving the conclusion implicit.