(aka external internal double crux)
TL;DR: Most aspiring rationalists are compartmentalized. To push towards coherence, such people should adopt, as a principal mode of their intellectual conversations, the practice of making arguments and sharing information in support of coherent positions different from their own all-things-considered position. I suggest "Devil's Dialectic" as a phrase to describe this sort of conversation, in the interest of decreasing its referential distance from the rationalist CK concept of a conversation.
Say I'm compartmentalized, so that some of my mental models disagree with each other, and some of my goals fail to take advantage of some of my relevant mental models. But, I want to decompartmentalize (with the safety measure of not willy-nilly overwriting some of my knowledge) by taking ideas seriously. In particular, if I have mental models that should co-refer to the world, but instead each have their own siloed idiolect, then I want to them to contact each other to build a shared idiolect by analogizing their domains and resolve disagreements by reason and observation; and I want to show my goals how they can control the world through the gears provided by my models. And further, when I encounter new information and ideas, I want to propagate the implications of that information across all my mental models and goals (or a relevant subset, trading off against computation cost).
To that end, it can sometimes be useful to respond to someone presenting information, arguments, or models, by engaging in a Devil's Dialectic. A devil's dialectic is a discourse between two perspectives in which one of the perspectives is not presenting zir all-things-considered, action-ready model of the world, but instead presenting a model held by some other perspective (i.e. making statements and arguments generated by that world model). That other perspective might be a sub-perspective; or might be a future-self perspective; or might be a hypothetical perspective ascribed to some other real perspective. A devil's dialectician, talking with someone presenting a position P, looks to see if there's a substantial "compartment" in zem that thinks not-P; and looks to see if there's implications of P such that at some future time, in some plausible situations, ze would seriously question P; and looks to see if ze respects the epistemics of some other perspective that thinks not-P. Then ze focuses on presenting the contrary position, at the cost of not computing the concordant position.
A Devil's advocate will argue for a position even if ze doesn't think the position is plausible, or doesn't care whether or not the position is true, or has no intention of updating zir beliefs no matter how the argument goes; ze just tries to come up with whatever are the strongest arguments ze can think of for the position. Thus a devil's advocate is a degenerate edge case of a devil's dialectician, in that ze presents a perspective that's perhaps logically coherent, but otherwise adversarially chosen to apparently provide evidence against the opposing position. On the other hand, a devil's dialectician engaging in a devil's dialectic, although ze does argue for a position even though ze would not take actions on the basis of that position, nevertheless is presenting a position genuinely held by some perspective, which position is therefore amenable to merging with any other genuine position given enough double crux and empiricism.
When a devil's advocate hears someone say a true statement of the form "wait, you're arguing for X, but you surely also believe Y, and doesn't Y imply not-X?", ze might get flustered or angry and will try to question or distract from "Y" and "Y implies not-X". When a devil's dialectician hears the same thing, ze will gratefully take the opportunity to perform an internal double crux; ze is grateful that zir's interlocutor gifted to zem the cognitive work needed to point out a contradiction between two of zir's sub-perspectives.
The dialectian is being lazy if ze could IDC on zir own, but ze does a devil's dialectic anyway. The devil's dialectic is for when the contrary position is barely within reach, perhaps because it's complex or perhaps because it's slippery to mentally access, and therefore demands full attention.
A devil's dialectic is harmful if one perspective incorrectly thinks the other is presenting zir all-things-considered position; the interlocutor might incorrectly update that the dialectician holds dumb opinions, or might incorrectly update to believe the dumb opinions expressed by the dialectician. Similarly, a dialectic is harmful if one perspective incorrectly thinks the other is trying to write to social / political narratives and plans. Devil's dialectics are risky because they can provide cover for someone who's compartmentalized and doesn't intend to decompartmentalize themselves and is doing something antisocial with their compartmentalization. Allowing devil's dialectics increases the risk of people losing the sense that their words are connected to meanings and models, which are connected to observations, actions, and outcomes.
I suggest this kind of conversation should have a distinctive name. Can anyone suggest a better term than Devil's Dialectic? External internal double crux? EIDC doesn't quite capture the idea of actively search for genuine contrary perspectives, which seems a bit more devilish than IDC. Also, did I communicate the idea at all?