Only endorsements posted publicly (mainly to ACX) count.
To be clear, this resolves YES if any endorsement is made in the primary or in the general election. Any presidential endorsement (as long as it's not private, or an obvious joke, or otherwise opposed to the obvious spirit of this market) for the 2024 election results in a YES.
Related markets
Jan 4, 8:40pm: Will Scott Alexander endorse any presidential candidate in 2024? → Will Scott Alexander endorse a presidential candidate in 2024?
@ScottLawrence What about multiple candidates? The blog post in question was titled "SSC ENDORSES CLINTON, JOHNSON, OR STEIN"
@ScottLawrence I definitely would've assumed that would resolve to yes, the market says "any", not "one".
@MichaelLucy I've changed "any" to "a" in hopes of reducing confusion a little bit.
For me, saying "I endorse X or Y or Z" is not really what I mean by "endorse", even though the word "endorse" is used. But I agree it's debatable.
For the record, if he says "I endorse Biden", and then later says "I change my mind, I endorse Trump", that's still a YES---even though more than one candidate was endorsed. (I hope that's what you'd have expected.)
@MichaelLucy wait, in english "any" is a multiple-container term? I have always felt it is used with single objects.