Open Thread: What’s The Second-Best Cause?

I’ve re­cently read the book Epic Mea­sures, about the global bur­den of dis­ease studes. One per­son in­volved in the stud­ies had a habit of ask­ing peo­ple who said their in­ter­ven­tion was the most im­por­tant, “what in­ter­ven­tion is the sec­ond most im­por­tant?”

It was in­tended as a gotcha, but I think it’s ac­tu­ally a re­ally in­ter­est­ing ques­tion that sheds a lot of light on cause pri­ori­ti­za­tion, and I’ve got a lot out of think­ing about it.

So: peo­ple who pri­ori­tize a sin­gle char­ity, in­ter­ven­tion, cause, or broad area in which to work, what char­ity/​in­ter­ven­tion/​cause/​broad area in which to work is sec­ond-best, and why?