Group attribution error
We assume a group's choices reflect every member's personal beliefs.
What it means
The error of inferring that the attitudes and dispositions of individual group members match the decisions or composition of the group as a whole, ignoring how group-level outcomes can diverge from any member's preference. It has two faces: treating a group's decision (often the product of leadership, procedure, or compromise) as if it expressed the inner view of each member, and inferring an individual's traits from the perceived character of their group. The mechanism blends representativeness with a neglect of the situational and structural forces that shape collective action. It is a close cousin of the fundamental attribution error applied to aggregates. It distorts how we read electorates, juries, committees, and entire nations.
Examples
Assuming everyone in a country personally endorses a policy its government enacted, when the vote was close and many citizens opposed it.
A customer berates the checkout assistant over the chain's new bag charge as though she had voted for it, when it was decided in a head office she has never once visited.
A committee waters a proposal down to reach consensus, and each member is afterwards assumed to hold the bland compromise position that, in fact, not one of them argued for.
First described in Allison & Messick (1985).