Goldberg: Bill, what’s the biggest failure?

Gates: We’ve been trying to develop an HIV vaccine that we don’t yet have. We’re trying to get other tools, like a daily pill or a gel for women, and that’s taken a lot longer than we expected. This letter to Warren doesn’t focus on our education work. There, our goal of raising the math scores and literacy scores for the nation as a whole have not been achieved and I would say we’ll probably get the HIV vaccine before we see math scores go up a lot. The greatest successes are in public health, even though we have our difficulties. We are still optimistic in our education work. It turns out that it’s easier to catalyze in health. When we started, we thought that some health problems would be easy and some would be hard, our success on pneumonia and diarrhea has gone faster than we expected. Polio, with a little bit of luck, will be this incredible success story.

Goldberg: Warren, did you ever think you would know so much about diarrhea?

Buffett: Bill gets more excited about these things than I do, certain aspects of it at least.

Goldberg: At a public appearance at Columbia University several years ago, the theme of the event, you may recall was, “Keeping America Great.”

Buffett: We want a royalty.

Goldberg: There are a lot of lawyers between you and those royalties. So, does America need to be made great again?

Buffett: We are great! We are great!

Goldberg: Why do people think we need to be made great again?

Buffett: I don’t know. In 1776, there were four million people here, and 290 million in China. We have 75 million owner-occupied homes, 260 million vehicles, the greatest universities in the world, up and down the line—all of this from nothing 240 years ago. That’s pretty remarkable. There’s no one at the border saying you have to have a 140 I.Q. to get in, or a propensity to work 60 hours a week, but certain ingredients have created a miracle here. You had a welcoming attitude toward immigrants who then did wonders for this country.

Goldberg: But why do certain voters think we need to be made great again?

Gates: Politics goes back and forth. For instance, the fact that healthcare is so hard to get right, and expectations exceed what is being delivered—this causes frustration. The financial crisis, and how we should have reacted to that—I think a lot of people feel that we didn’t have a great resolution to that. Democracy is going to go back and forth on lots of and lots of issues. But things like scientific progress, or inventing new vaccines, or helping teachers be better—those things will be enduring assets, for the U.S. and for the world.

Look, I don’t have differential expertise in explaining political outcomes. Ask me about the immune system—

Buffett: Ask him about diarrhea! I can just see the headline now!