With Modern Monetary Theory (MMT) making inroads in the public policy debate, some New Keynesians have transitioned from ignoring or dismissing the approach to engaging with it. This is healthy for both sides. There has been a tendency, though, to make “we’ve known it all along” type statements. A comprehensive response to the “nothing new” claims is provided by Bill Mitchell in a recent three-part series of posts (part 1, part 2 and part 3). My focus here is narrower and concerns a view (for example, expressed in a considered response here) along the lines that MMT has nothing new to say when the economy is at full employment.