Asymmetry and Overdetermination in Swain's Counterfactual Theory of Causation

Hume's second definition of causation described effects as being counterfactually dependent upon their causes: one 'object' caused another "where, if the first object had not been, the second never had existed." This definition lay dormant for more than two centuries before it was revived and given its best known formulation by David Lewis. Several years ago, however, an alternative analysis of causation using counterfactuals was suggested by Marshall Swain. I wish to examine Swain's account critically as a potential alternative to Lewis's.