Counterfactual definiteness

Counterfactual definiteness is a way of talking about things that haven't happened but could have happened. It's like a pretend game, where you imagine something different to what actually happened. For example, if your friend jumped off the bridge, but you stopped them, you could say "I stopped my friend jumping off the bridge, counterfactually they would have jumped". This means that you stopped them, so they didn't jump - but if you hadn't stopped them, they would have jumped.