Catherine Rampell: If the tax bill is so great, why does the GOP keep lying about it?

Nearly every claim Republicans are using to market their tax plan is at best a distortion, at worst a deliberate falsehood.Which raises the question: If their plan is really so great, why not sell it on the merits?Consider just a few of the Republicans’ key talking points and their tenuous relationship to reality.1. The tax cuts will pay for themselves.Republicans claim that tax cuts will unleash boundless economic growth. Through that growth, we’ll all become richer. And as our inco