Counterfactuals

What are counterfactuals and what is their point? In many cases, none at all. It may be true that if kangaroos didn''t have tails, they would fall over, but they do have tails and if they didn''t they wouldn''t be kangaroos (or would they?). This is the sort of thing that can give counterfactuals a bad name, as inhabitants of a La La Land of the mind. On the other hand, counterfactuals do useful s...