the objective ‘ought’ and the three-envelope problem
We left off with the failure of two state of the art views about the subjective ought to explain why Margaret ought to choose envelope three. The problem with those views is fundamental. The problem is that they tie what one ought to do too closely to what one believes. It doesn’t seem like this is what matters. Instead, it seems that what matters is the information accessible to Margaret–i.e. what matters is what information state Margaret is in.
My first suggestion is that we ought to rethink the traditional distinction between the subjective/objective ought. Instead of thinking that A ought to 
One thing that we learned from discussing the views about the subjective ought is that what seems important is not what one believes, but what information is in one’s information state. Other cases besides Margaret’s support this. Imagine that Nathan is assembling his son’s stroller. Although he has the instruction manual out, he doesn’t pay much attention to it. He thinks that his handy-man instincts are sufficient for successfully assembling the stroller. As it happens, he fails to to attach an essential screw. When he first takes his son out for a stroll, the stroller breaks and his son is injured. It’s natural to say that Nathan should have paid attention to the instruction manual. This is because, I suggest, Nathan was in a position to know that attaching the screw was part of the assembly process. Generalizing, I want to say that one’s information-state consists in the propositions one is in a position to know.
Another thing we learn from reflecting on the cases is that what is important isn’t any old proposition that one is in a position to know. It seems that what matters are the reasons one is in a position to know. The proposition that there is $1000 in envelope three is one of the propositions in Margaret’s information state that matters w.r.t. what Margaret ought to do. Similarly, the proposition that the screw is essential for the stroller’s safe assembly (or something along these lines) is the proposition that matters w.r.t. what Nathan ought to do.
These thoughts lead naturally to the following proposal, which we’ll call Objective O:
objective o: Necessarily, one objectively ought to
iff the set S of objective reasons that A is in a position to know has the following property: S decisively supports
Objective O gives a nice explanation of why Margaret ought to choose envelope three. The relevant reasons are that there is $1500 in envelope one and that there is $1000 in envelope three. Margaret isn’t in a position to know the former reason and is in a position to know the latter. Thus, the latter is in S and the former isn’t. Thus, it’s obvious that S decisively supports choosing three. Objective O thus entails that Margaret ought to choose envelope three. Moreover, Objective O doesn’t have the problems of that the accounts of the subjective ought do.
Unfortunately, there is a problem. Imagine that instead of there being $1500 in envelope one, there is $15,000,000. As in the original case, imagine that Margaret is told that there $15,000,000 in either envelope one or envelope two and that there is $1000 in envelope three. Under normal circumstances, Margaret would be slightly crazy for choosing envelope three. It’s clear, that is, that Margaret is not obligated to choose envelope three in this case.
The problem for Objective O is that Margaret is in a position to know the same reasons in this case that she is in the original case. Specifically, she is not in a position to know the reason to choose envelope one (that there is $15,000,000 in envelope one). Thus, it seems as if Objective O entails that Margaret ought to choose envelope three in this case as well. This is intuitively false.
I don’t think that this is a problem for Objective O. Instead, I think it’s a problem for an assumption implicit in the dialectic so far–viz. that the following proposition isn’t an objective reason: that there is $15,000,000 in envelope one or envelope two. Call this proposition Disjunction. The thought is that since envelope two is empty, there cannot be a reason supporting the act of choosing envelope two.
Why should we think that Disjunction is a reason? I won’t fully defend the claim here, but gesture at my more complete argument. There are a few reasons to think that Disjunction is an objective reason. One, it’s plausible that Margaret ought to take Disjunction into account in deliberation. To see this, imagine that Susan is in a similar choice situation as Margaret. Unfortunately for Susan, she doesn’t know anything about what’s in envelope one or two. Suppose Margaret and Susan encounter each other, and Margaret tells her what she knows about the first two envelopes. Susan should take Disjunction into account in her deliberation about what she ought to do. Moreover, it’s not simply because Susan believes Disjunction that she ought to take it into account in deliberation. Like Nathan and Margaret’s reasons, Disjunction seems like it’s something Susan ought to take into account in deliberation regardless of whether she believes it.
A second reason to think Disjunction is a reason is that it seems to have weight. We seem to take this as obvious when we make a judgment about the revised case (the $15,000,000 case). Call that there is $1500 in either envelope one or two Disjunction-1. Disjunction seems like a weightier reason than Disjunction-1. A fortiori, Disjunction is a reason. Disjunction can also have less weight than other reasons. Imagine that there is a fourth envelope, and that Margaret is told that there is $15,000,000 in either envelope one or envelope two and that there is $16,000,000 in either envelope three or envelope four. Call that there is 16,000,00 in either envelope three or envelope four Disjunction-2. Disjunction-2 is weightier than Disjunction. But that can be true only if both are reasons.
I take it that these considerations are independent reasons to reject the assumption that there is no reason to choose envelope two. Disjunction is a reason to choose either one or two. Similarly, that there is $1500 in either envelope one or two (call it Disjunction-3) is a reason to choose envelope one or two.
In the revised case, Margaret is in a position to know Disjunction; thus, it’s in S. Moreover, it’s plausible that Disjunction decisively outweighs Margaret’s reason to choose envelope three. So, in the revised case Objective O entails that Margaret ought to choose envelope one or envelope two. But what of the original case? Margaret is in a position to know Disjunction-3 in the original case; thus, it’s in S. However, Disjunction-3 is not nearly as weighty as Disjunction. In fact, it is intuitively plausible that Margaret’s reason to choose envelope three decisively outweighs Disjunction-3. Thus, it’s intuitively plausible that Objective O still entails that Margaret ought to choose envelope three in the original case.
As it turns out, this cannot be the end of the story; that’s because Objective O gives rise to another puzzle. What that puzzle is and my proposed solution will have to wait for another day.
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