One of the more interesting comments to come out of the Juan Williams brouhaha (as opposed to a foofarah) is this one by Doctor Zero, "Juan Williams And The Preference Cascade". A "preference cascade" is a phrase he borrowed from Instapundit himself, Glenn Reynolds, and the good Doctor defines it thusly: "a preference cascade occurs when people trapped inside a manufactured consensus suddenly realize that many other people share their doubts." That consensus might be "manufactured" in a variety of ways, some crude, some subtle -- e.g., a crude totalitarian surveillance, or a more subtle social imposition of "right thinking" -- but however it's done, it becomes increasingly fragile under circumstances that undermine it, including, obviously, those who question it. At some point, there need be only a small event, a single voice, to trigger the "preference cascade" that suddenly shatters the consensus. Doc Zero's contention is that Williams was fired because he threatened to be that voice, with the firing intended to shore up the consensus by sending the message that such sentiments, such "feelings", cannot even be expressed within the confines of the bien pensant liberal orthodoxy that NPR symbolizes.
Whatever the case may be with respect to this episode, however, I think the idea of a preference cascade is a handy one, in the way it can be used to explain fairly sudden, and otherwise quite surprising, changes, not only in political groups, but within individuals as well. It's not just a social consensus, in other words, that gets undermined or hollowed out by disconfirming events, it's also one's own overt beliefs. One can continue to think of oneself as liberal or conservative, left-wing or right-wing, even as one's opinions about this or that particular issue are the opposite of one's long-standing self-labeling -- until something occurs, and it may be quite small in itself, that precipitates a kind of internal cascade, and the old labels just don't seem to have the same relevance any longer. It's why change sometimes seems to come in lurches.