Tyler Cowen writes,

David R. Henderson asks me to list three policy areas where my views are uncertain. Since this blog (or at least this author) has been streaming uncertainty for over four years, this strikes me as an odd request.

In my essay on books of 2007, I said that Cowen and Dani Rodrik are notable for the way they allow for disagreement and self-doubt.

In my view, it is easier to talk with certainty about what won’t work.1. On health care, I am certain that single-payer system will not produce enough efficiency to solve the financial problems of health care. After all, Medicare is more fiscally unsound than our private health care system. As an aside, while I was in St. Louis we had dinner with a retired doctor. She told of an incident where, as a patient, she went to see a dermatologist about a rash. The dermatologist looked at her and told she was fine. This proved to be correct. However, he billed Medicare for $700 for surgery. She called Medicare to report the fraud, and, after she finally got through after considerable time in voice-mail hell, the person told her that, “No, everything is fine. Our records show that you had the surgery.”

2. On education, I am certain that no policy will deliver major differences in results. I think that vouchers are rational, and I think that progressive vouchers would be more egalitarian than our current system. I hate the way that public schools are used for propaganda purposes (such as showing “An Inconvenient Truth”). But I don’t think anybody has a replicable solution for better education.

3. On Social Security, I am certain that locking in the current statutory retirement age forever is misguided.

4. On global warming, I am certain that My Global Warming Question will not be answered for decades. Meanwhile, Bil McKibben, citing James Hansen, is certain that we already have enough atmospheric carbon dioxide to send the earth on an explosive path for warming. It seems as though we should know within ten years if they are right.

5. On biodiversity, I am certain that humans have more control over the fate of large animals than that of smaller species. It is sobering to think that we dictate where animals weighing more than a few pounds can live. In our cities, a shi tzu can survive but a wolf can’t.

6. On drugs, I am certain that in the coming decades research and development will produce drugs that are more morally problematic than any of the drugs that are illegal today.

7. On immigration, I am certain that no immigration policy under consideration is going to have a big effect on the incomes of the unskilled in America.

8. On foreign policy, I am certain that if the United States is less assertive, those who become more assertive will not be characterized by peaceful beneficence. That does not mean that we should be assertive, but do not be surprised if our withdrawal ends up increasing rather than decreasing the amount of ugly events that occur in the world.

9. On water policy, I am certain that giving some segments (e.g., California farmers) subsidized access to water is not the best approach.

But basically I agree with Tyler. I am not certain what is the best approach. On health care, our system has so many flaws that single payer might be an improvement–although not nearly the improvement that its enthusiasts promise. On global warming, I think that it is possible that the models are under-predicting global warming, whether or not it is caused by our carbon emissions.