When Rand Paul ran for the U.S. Senate, my worst case rating of him, out of 10, was about a 4, and my best case was about a 7. One of my biggest concerns was that he seemed to waffle on the issue of war. Seeing him on Letterman the other night and reading his “Dear Colleague” letter about the USA PATRIOT Act, I would now give him at least an 8. It’s not just the views he expresses, but also the sensible, compelling way in which he expresses them.

Some of the other commenters who commented on his appearance on Letterman pointed out how weak Letterman was, disagreeing with Paul but not being able to articulate why. I agree with those criticisms. But I guess I’m a glass-half-full kind of person, always looking for little cracks in the concrete through which the sunlight can stream. And I saw a lot of cracks in Letterman’s concrete: even when he disagreed with Paul, he often admitted his own ignorance. How many people do that? Here are some highlights:

2:10: Paul quotes Al Franken saying that Letterman isn’t that funny. (I take this as a shot across Letterman’s bow. Strategically risky, but it seemed to work.)

5:55: Paul says fire protection is a basic government service. (Rand Paul should read Fred McChesney, “Smoke and Errors,” for some U.S. history of volunteer fire departments.)

6:20: Letterman: “Are we hurting the middle class, guys like you and me?” Excuse me? Letterman is middle-class? In that case, words have lost all meaning. Notice the slight laughter after he says that. This is too much for even Letterman’s audience.

6:40: Paul does a nice job of talking about incentives in the market vs. in government.

7:50 to 8:10: Again, Paul talks nicely about market signals.

8:50 and following: Paul lays out how much of the federal income tax is paid by high-income people (he says that people making $70K and above pay 96% of the federal income tax) and Letterman says, “I think there’s something wrong with those numbers: I don’t know what it is exactly, but I’m pretty sure there’s something wrong with them.” There was something wrong with them. According to the Tax Foundation, in 2008, the top 50% paid 97% of the federal income taxes, but the adjusted gross income defining the top 50% was $33K, not $70K. This is a big difference but I think Rand Paul got the basic point right. Check out the Tax Foundation’s numbers. And I’ll bet dollars to doughnuts that if Rand Paul got the numbers right and came back on the Letterman show to say, correctly, “In 2008, the top 25%, those with adjusted gross incomes of $67K or more, paid 86% of the total taxes paid,” Letterman would still say, “I think there’s something wrong with those numbers.”

9:15: Here’s the refreshing part. People applaud Letterman for saying there’s something wrong with those numbers–that’s not refreshing. What’s refreshing is that Letterman responds to the applause by saying, “Thank you; you’re applauding my stupidity.”

11:00: After Rand Paul says that competition makes things better, including for late-night talk-show hosts, Letterman says to the audience, “I think he’s wrong about some of these things: I just can’t tell you why.”

I know there will be people who get down on Letterman for talking this way–saying that that there’s something wrong, but he can’t put his finger on it–but I think that confession of ignorance is the first step toward understanding.