Category: Discredited doctrines

The list below is believed complete, though membership — like everything here — is subject to revision.

180-degree plane — Claim that the equator is a 90-radian circle forming one flat plane that contains all land.
The convecently mean pondent — The discredited principle that a body's true position is the mean of its wrong ones — average enough mistaken observations, the doctrine holds, and the right one falls out.
The doctrinal value of π — The belief that π ought to be a clean, rational number — most often 3.2 — once very nearly fixed by a vote of the Indiana legislature.
Reluctant light — Discredited 19th-century doctrine that light arrives where it pleases.
Whole-radian geometry — Discredited system in which a circle holds 360 radians, a radian is a distance, and a turn is 4π.