Sufficiency Principle: S’s doing A promotes p if it causes p to obtain.
For example, Behrends & DiPaolo (p.4) offer the following case, where Julie supposedly "promotes" her desire by pressing the button, even though it's no more likely to be fulfilled than if she did nothing (it is guaranteed either way):
Buttons 2. Julie has some desire. There is one button in front of her. She knows that if she pushes the button, her desire is guaranteed to be fulfilled. However, unbeknownst to Julie, if she does not push the button, Black will ensure that her desire is fulfilled.
Eden convincingly argues that we needn't accept the sufficiency principle. I'm inclined to think, stronger still, that we positively should not accept it. Here's why.
We are interested in the notion of "promotion", I take it, just insofar as it is normatively significant -- related to what reasons we have. But Julie has no (objective) reason to push the button in the above case. To see this, note that any reason must have some positive weight, and thus be such that there could be some, weaker, countervailing reason that it could outweigh. But Julie's putative reason to press the button in order to promote her desire could not outweigh any countervailing considerations whatsoever. The very slightest cost would make it more worthwhile for her (objectively speaking -- she might not realize this, of course) to do nothing and let her desire instead be fulfilled by Black's backstage machinations. So this putative reason, having zero normative weight, turns out not to be a normative reason at all. So pressing the button does not "promote" Julie's desire, in any normatively significant sense.
(Or, I suppose, one could say that doing nothing promotes her desire equally well, and hence precisely counterbalances her instrumental reasons to press the button. But this seems a merely verbal difference from saying that she has no reason to press the button at all, given that her desire will be fulfilled just as well either way. And there seems no basis for insisting on the former way of talking -- or for rejecting views that involve the latter alternative -- as the Sufficiency Principle would require of us.)
[Update: Happy to see that Eden's final paper, now incorporating this argument, is forthcoming in PPR!]