Shortest version: How seriously do your ideas diverge from those of your relevant status group?
We can establish rather firmly that people are willing to hold positions for several reasons. Among those reasons are:
- Group identity/status/taboo (I'd like to fit in).
- Rebel signalling (I'd like to stand out)
- Truth-thinking (I think it's right).
If there is none, then we are indistinguishable from opinions existing purely for group-fit reasons with no thought at all. Hence, one can dismiss most Randians as not thinking much because their opinions diverge in no (costly) way from those of the late author. Because they diverge in no costly way, the assumption should be that they agree for status reasons. The same applies for most Evangelicals and most Environmentalists: they have no costly disagreements inside their groups, so should be treated as not thinking.
The difficult problem to address is distinguishing between Rebel Signalling and Truth-Telling. This is why it's important to reference most costly disagreement, rather than biggest disagreement. If the Environmental caucus wants their caucus-fruit to be an apple, and Bob the environmentalists takes a stand for Watermelon instead...that's low cost. If he argues pro-nuclear power, that's medium cost. If he argues anti-Obama, that's high cost. And if he argues that CAFE regulations hurt the environment, he's probably kicked out of the group. Watermelon bob might well be rebel-signalling. Anti-CAFE Bob is thinking (whether or not he's right).
So what group are you part of, and what belief of yours is costliest to your being accepted in that group ? (The belief cannot be a qualifier for a MORE important group: Joe the conservative-libertarian can't impressively list opposition to the flag-burning amendment as an anti-conservative position, because it is a pro-libertarian position).
Aside: This mechanism points at places where the wisdom of crowds should stink badly.
My most costly position at present? The opposition is saying something worth listening to/taking into account, and dismissing their position is universally wrong. This effectively makes all groups dislike me.
It seems as if Megan McArdle is also in this spot. Tyler Cowen seems to be here, but often veers into the rebel signal camp.