One of the common criticisms of the child tax credit from the right is that it will inexorably grow out of control. The actual history of the tax code tells a different story, I point out in my latest column. For middle-income families, the child credit is worth only a little more in inflation-adjusted terms than the equivalent tax break was in the 1940s — and parents get less tax relief than they did 20 years ago.

The debate about tax reform this year is proceeding amid widespread ignorance of this history.