discussing counterfactuals. These have been seen as a fundamental part of causality at least since 1748, when Scottish philosopher David Hume proposed the following somewhat contorted definition of causation: “We may define a cause to be an object followed by another, and where all the objects, similar to the first, are followed by objects similar to the second. Or, in other words, where, if the first object had not been, the second never had existed.” David Lewis, a philosopher at Princeton University who died in 2001, pointed out that Hume really gave two definitions, not one, the first of
...more
