This year has seen an alarming increase in the number of cases of the measles, a disease that seemed to have been eradicated by the turn of the century. Blame has rightly been placed on a newly envigorated anti-vaccine movement that thrives on junk science and fear.

The outbreak raises two crucial questions, which must be answered separately. There is only one answer to the first question — whether it is wise to refuse vaccinations. There is more than one answer to the second — how should the state respond to those who do.