On Twitter, Republican congressman Dan Crenshaw (pictured above) writes:

How about don’t knock on my door. You’re not my parents. You’re the government. Make the vaccine available, and let people be free to choose. Why is that concept so hard for the left?

University of Michigan economist Justin Wolfers gives a two-word answer:

Because externalities.

But that’s not enough.

I debated Justin in April 2020 about lockdowns: he favored them and I opposed.

In the debate, though, he made an important point about externalities that did affect my thinking. He pointed out that the standard law and economics solution to a negative externality is to have the “least-cost avoider” bear the cost of adjustment. I discuss what I learned from that here.

There’s a related point. Now that vaccines in the United States are widely available at a zero price and highly effective, who are at the lowest risk? The people who are vaccinated. They face very little risk–on the order of the risk from catching the flu in a normal flu year–whereas the unvaccinated person faces a much higher risk. So the people who should bear the risk are those who, for whatever reasons, don’t get vaccinated. And they should, as Crenshaw says, be allowed to bear the risk.

You can’t just say the word “externalities” and win an argument.