There are various economic models used to estimate how changes in tax policy will affect economic growth and budget deficits. They contain lots of variables and lots of assumptions. (Of course, don’t mistake the map for the territory and all that.)

But it’s pretty tough to find a legit model that suggests tax cuts pay for themselves. That usually doesn’t happen. The Reagan tax cuts didn’t pay for themselves. The Bush tax cuts didn’t pay for themselves. And the Trump tax cuts almost surely won’t pay for themselves. In other words, they are overall revenue reducing even if they boost economic growth somewhat. Doesn’t necessarily mean tax cuts are bad, just that they need to be judged in the broader fiscal context. The Reagan tax cuts, for instance, took place when the debt-GDP ratio was 25%. Now it’s three times that.

We can argue, of course, over the best way to model the impact of a tax cut. But this, from a column by economist Thomas Sowell, is about the worst way of judging a tax cut: