Sometime ago, Animesh had a post about various methods of proving a theorem. I didn't find 'proof by committee' there, but legitimation by committee is a time-honoured technique in management circles. Here's Bob Sutton quoting from a letter:
I feel so used for having [agreed] to be part of the building committee. I haven't felt this way since I came to [the university]. Not one thing I said or argued for the whole time mattered. Not one thing the consulting company who did the early study of our needs for space mattered.....[My wife] warned me when I joined the committee that they would use the faculty committee for legitimation and do what they wanted anyway.
Sutton describes this phenomenon in greater detail, and offers some advice to administrators and committee members about the best way to deal with it. For the unfortunate folks who end up participating in the committee work of a totally pointless kind, he advises some devious means of protecting themselves: For example:
In some organizations, a more socially acceptable strategy is to say you will join the committee, but to miss most meetings, and to arrive late and leave early when you do attend a meeting. I guess this is a safer strategy for anyone who wants to be an effective organizational politician. These latter strategies mirror institutional theory -- you as an individual can engage in "symbolic" membership in the committee, and thus have little or no impact on a committee that, in turn, has little or no impact. That way, you can ingratiate yourself with your superiors by pretending to support the sham, and everyone is happy that you are playing the meaningless game so well (except perhaps for the users whose needs are completely ignored).
These guidelines are, I confess, fairly obnoxious. [...]