Paul credited Jordan Ellenberg, a mathematician at the University of Wisconsin, with originating the vampire allegory in a 2013 blog post. The economist Russ Roberts, in turn, credited Paul in his 2022 book, “Wild Problems: A Guide to the Decisions That Define Us.”

“Wild problems,” Roberts wrote, “are untamed, undomesticated, spontaneous, organic, complex.”

Roberts cited the story of how Charles Darwin decided in 1838 to get married. Darwin made lists of “marry” and “not marry” scenarios, precisely as one would expect from a great scientist. At some point, though, he went with his gut. At the bottom of the page is scrawled, “Marry — Marry — Marry Q.E.D.” Which is Latin for “that which was to be demonstrated,” as if he had demonstrated anything except his own susceptibility to love.

The decision of whether to marry is hard for economists to grapple with because the usual method of toting up pluses and minuses doesn’t work well. Who are you trying to please? Today you or future you? Future married you will probably be happy, but he or she is a different person. Future you is you but also not you, if you know what I mean.

That said, most married people are thankful to their past single selves for deciding to wed. (I certainly am.) A 2004 study estimated that the size of the marriage effect on mental well-being in Britain and the United States was equivalent to having an extra $100,000 a year. One of the authors of that paper, Andrew Oswald of the University of Warwick, found in a paper he co-wrote a year later that the health gain from marriage “may be as large as the benefit from giving up smoking.”

Marriages don’t always work, and they’re not the only way to live and raise kids, as my Opinion colleague Ezra Klein observed in a June podcast. On average, though, I think children grow up best in intact, two-parent households, and married parents are more likely to stay together than cohabiting unmarried ones. In the early 1990s, 71 percent of children born to cohabiting unmarried parents could expect their parents to separate by their 12th birthday, compared with only 26 percent of children born to married parents, a 2008 study in the journal Demographic Research found. If maximizing the happiness of children and the adults they grow into is one of society’s principal goals — and it should be — then few things are more important than marriage.