Caution on Bias Arguments

Scott Alexander in Slate Star Codex:

Suppose A and B are debating some issue, and B is part of a group especially closely linked to the issue. For example:

1. A plumber and a teacher are debating a proposed pay cut for teachers.
2. A man and a woman are debating abortion.
3. An atheist and a Jew are debating the peace process in Israel.
4. A white person and a black person are debating slavery reparations.
5. A citizen and an undocumented immigrant are debating immigration policy.
6. King Edward and a Jew are debating whether to expel all the Jews from England.
7. You and a KKK Grand Wizard are debating whether the KKK should be banned as a hate group.
8. A scientist and a tobacco company executive are debating whether cigarettes are dangerous.

Who is more biased? A or B?

More here.