Alternate history as a test of historical causation

Counterfactual history works as a road-not-taken thought experiment only when grounded in what actually happened. A useful scenario identifies which variables must change before an alternative choice becomes viable. Those changes expose the constraints and priorities that shaped the real decision. Researchers once discovered that a familiar account relied on commentary by someone who was not the decision-maker; testing alternatives redirected attention to the people who actually made the choice and produced a different narrative. Used carefully, alternate history can therefore test causation and trace knock-on effects; simple invented outcomes do neither.