Should We Wear Masks Always and Forever? A Response to Bob Lawson

Michael F. Cannon

Economist Bob Lawson writes:

I have yet to see an argument for wearing masks (and distancing) now that doesn’t apply literally at all times. If you accept that masks have some effectiveness against spreading diseases, which seems reasonable, why should they not always be required? COVID-19 maybe 10x worse than say the flu and maybe 100x worse than other infectious diseases (even common colds can kill) but these diseases kill too. If masks are morally required now, why not before, and why not forever more?

Probably lots of people are wondering the same thing.

There is an argument for wearing/​requiring masks now that does not apply at all times. It is that COVID-19 may have increased the benefits of masking to the point where the benefits of broader masking now exceed the costs. That rationale may apply now but may fail to apply at some point in the future if the benefits of masking falls.

We don’t usually think about masking and other infection‐​control measures in terms of supply and demand curves, because these activities do not involve economic exchanges. But that framework provides the clearest way to think about when people should adopt such measures. It doesn’t provide a specific answer. But it tells us the optimal quantity of masking is the point at which marginal cost equals marginal benefit.

Masking is a service with both costs and benefits. Some person‐​minutes of masking are low‐​cost. Other person‐​minutes of masking are very costly. When we assemble these person‐​minutes in order of cost, they form a marginal‐​cost/​supply curve.

The tricky part is the benefits. Since masking involves positive externalities, the demand curve (which reflects willingness to pay) is not the same as the marginal‐​value curve (which reflects total social benefit). The marginal‐​value curve is (much) higher than the demand curve, which is another way of saying the value of each person‐​minute of masking is greater than what anyone is willing to pay you to do it. That’s a pity, because the total‐​social‐​value/​marginal‐​value curve is much harder to observe than the demand curve.

And it only gets trickier from there. Masking also involves positive network externalities. That’s a fancy way of saying my decision to wear a mask can increase the value of your decision to wear a mask. Do you know what that means, kids? Multiple pairs of demand and marginal‐​value curves that form a new, composite marginal‐​value curve!

All this stuff is so inscrutable, we really couldn’t tell what the optimal level of masking was even prior to COVID-19. It may have been the case that lots more masking would have produced large net benefits in terms of reducing morbidity and mortality from flu and other bugs.

When COVID-19 emerged, it permanently increased the value of each person‐​minute of masking relative to a COVID‐​19‐​free world. (Equivalently, it shifts all of those component demand and marginal‐​value curves, and the composite demand curve, to the right.) COVID-19 made it much more likely that lots more masking would produce large net benefits.

But it may not always be the case that we should sustain existing masking levels forevermore. The value of masking falls as herd immunity, innovations in treatment, and other factors make COVID-19 and other airborne pathogens less of a threat. So even if masking makes sense now, it might not make sense later.

After all the complexity, the response to Lawson’s challenge boils down to this.

1. It may have made sense to mask more often pre‐​COVID‐​19. We really don’t know.
2. COVID-19 has permanently increased the value of masking. We don’t get to go back to the old normal where the value of masking was lower.
3. Economics confirms what intuition suggests: it makes sense to mask more often now. We really don’t know how much more.
4. Contra Lawson, that doesn’t imply we should mask all the time. (Wear a mask while sleeping or swimming? Probably not a good idea.)
5. That’s because masking isn’t an either/​or/​forevermore sort of thing. It’s a question of balancing marginal costs and benefits.
6. Even though COVID-19 permanently increased the value of masking (that is, relative to a world without it), the value of masking could still fall over time if vaccines, medical treatments, or other factors reduce the value of masking.

I am curious to know what Lawson thinks about this analysis.