Definition
Plain language
Asking what would have happened if you had done something differently.
As stated in the literature
In Pearl's framework, the top rung of the ladder of causation: reasoning about outcomes under hypothetical alternative interventions.
Also called: counterfactuals, counterfactual reasoning
Why it matters: Counterfactual reasoning is what separates real causal understanding from pattern-matching on correlations.
For example, asking 'would the patient have survived if they had received the drug?' is a counterfactual question, distinct from observing survival rates among those who actually got it.
Heard on the show
“You run a counterfactual.”Episode 026 — What RL Actually Does to Language Models, at the Token Level