 A famous impossibility theorem by Peter Gärdenfors (1986, 1987) shows that the Ramsey test is incompatible with a set of plausible postulates for revision. Several solutions to the impossibility theorem have been put forward. One option is to reject the Ramsey test as a criterion for the validity of conditional sentences (Rott 1986). Another, proposed by Isaac Levi, is to accept the test as a criterion of validity but deny that such conditional sentences should be included in the belief set when they are valid (Levi 1988. Arló-Costa 1995. Arló-Costa and Levi 1996). Several other proposals have been put forward. However, it is fair to say that operations of AGM-style belief change have not yet been constructed that are generally recognized as able to deal adequately with conditional or modal sentences.