fallacy

Motte-and-bailey

Also called: Motte-and-bailey fallacy, Bait and switch

In a motte-and-bailey argument, someone advances a bold, hard-to-defend claim (the bailey), then retreats to a modest, easy-to-defend claim (the motte) when challenged, and returns to the bold claim afterwards.

How it works

The two claims are run together as if they were one. Critics of the bold claim are made to look as if they deny the obvious modest one.

Examples

Bold: "This diet cures most illnesses." Challenged: "I'm only saying eating vegetables is good for you."

Nobody disputes the modest claim; the bold one is what needs evidence.

Bold: "The media is completely controlled." Challenged: "I just mean outlets have editorial biases."

Editorial bias is easy to defend; total control is a different, much stronger claim.

How to spot it

The claim shrinks under challenge and grows back later.
Critics are accused of denying something obvious.
Two different claims share one slogan.

How to respond

Name both claims explicitly and ask which one is being defended.
Agree with the modest claim and return to the bold one.
Ask for evidence that matches the strength of the claim.