Pearl's Causal Hierarchy

Pearl's Causal Hierarchy describes three levels of understanding causality. The first, association, involves noticing correlations or patterns in data—like seeing that ice cream sales rise with hotter weather. The second, intervention, considers what happens if you actively change something—for example, introducing a new medication and observing effects. The third, counterfactuals, explores hypothetical scenarios—such as asking if someone would be healthier if they had taken a different treatment in the past. This hierarchy helps clarify how deep our understanding of cause-and-effect is, from simple observations to complex "what if" questions.