Why "yeah, but" shuts down a conversation

Because the "but" cancels the "yeah." The other person hears the agreement as a formality and waits for the real message, which is a no. After a few rounds of that, they stop offering ideas and start guarding the ones already on the table.

Negotiation expert William Ury points to a second reason in Getting Past No: people resist an idea partly because of who it came from. "If it is your idea, he may reject it for that reason alone." A "yeah, but" makes that worse, because it tells them from the first word that their idea is about to lose to yours.

Usually not. People disagree, and "but" is an ordinary word for it. What's worth noticing is the run: "yeah, but" answered with "yeah, but," three or four times in a row. By then neither of you is weighing the other's point. You're both just waiting for a gap to reply into.

Then say so, after the yes. Ury's advice in the same book is "Don't Say 'But'; Say 'Yes . . . And'." Agree with the part you honestly can, then add your view with "and." "Yes, the deadline is tight, and I still think we should move the launch" is still a disagreement. The difference is that the other person hears their point acknowledged before yours arrives, so they have less reason to defend it.

What works instead → Why people get defensive when you correct them

Related: Red flags you're missing: 7 signs a conversation is about to go off the rails