 Lewis argued that this could not be the correct set of truth conditions for p □→ q in general. His argument was that strict conditionals were in a certain sense indefeasible. If a strict conditional is true, then adding more conjuncts to the antecedent cannot make it false. But intuitively, adding conjuncts to the antecedent of a counterfactual can change it from being true to false. Indeed, intuitively we can have long sequences of counterfactuals of ever increasing strength in the antecedent, but with the same consequent, that alternate in truth value. So we can imagine that (3.1) and (3.3) are true, while (3.2) and (3.4) are false.