The House Republican tax reform plan unveiled on Thursday is likely to go through many changes before it has any chance of becoming law. But there’s one aspect of the plan that Republicans should stick with: limiting the mortgage interest deduction, which is one of the most distortionary aspects of the tax code.

In an ideal world, the only purpose of tax policy should be to raise revenue in an efficient and predictable manner to finance limited government functions. In practice, the U.S. tax code is riddled with provisions to aid certain special interests and to steer human behavior.