Congressman Ryan: You can cut tax rates by 20% and still preserve these important preferences for middle-class taxpayers.
Vice President Biden: Not mathematically possible.
Mr. Ryan: It is mathematically possible. It’s been done before. It’s precisely what we’re proposing.
Mr. Biden: It has never been done before.
Mr. Ryan: It’s been done a couple of times, actually.
Mr. Biden: It has never been done before.
Mr. Ryan: Jack Kennedy lowered tax rates, increased growth. Ronald Reagan…
Mr. Biden: Oh, now you’re Jack Kennedy?
(Laughter)
Mr. Ryan: Ronald Reagan — Republicans and Democrats…
Mr. Biden: This is amazing.
Mr. Ryan: Republican and Democrats have worked together on this.

* * *

Let us just say at the outset, we don’t think Vice President was lying when he disputed the notion that tax cuts on the margin can boost growth, jobs, and tax revenues. He and the rest of President Obama’s camarilla just find it excruciatingly awkward that one of the great tribunes on this head was President Kennedy. This is the issue on which Mr. Ryan, though he wasn’t as aggressive as Mr. Biden and didn’t smirk, won the debate on the substance. The president stands for dividing up the pie rather than growing it and Governor Romney stands for growing the pie so everyone gets a bigger slice.

The first thing we did after the debate ended was go up on the World Wide Web and watch JFK’s explication of the point. We issued an editorial about the clip in January 2011, as President Obama was getting ready to deliver his State of the Union speech. The left wing of the Kennedy family never fails to get annoyed when the clip is used to buttress a Republican candidacy. But it has rarely seemed more apt than on the occasion when Mr. Ryan used it.

Mr. Ryan sounded supply-side themes throughout the debate. The word “growth” was used five times in the to-and-fro, four by Mr. Ryan and once by Mr. Biden quoting Mr. Ryan and sneering as he did it. Taxes and growth are one of the issues for Messrs. Romney and Ryan to hammer home in the closing weeks of the campaign. Mr. Biden said he didn’t know what the unemployment rate was four years ago in his home town of Scranton. Mr. Ryan reminded him that it was lower at the start of the Obama term than it is today. Tax cuts, growth, jobs, revenue growth. It was startling this evening how much clearer Mr. Ryan grasps the principles than Mr. Biden — and how far left the Democrats have drifted since the days of JFK.