Published online by Cambridge University Press: 01 January 2022
I defend a formulation of the Ramsey Test with a condition for accepting negations of conditionals. It is implicit in the assumptions of the triviality theorems of Gärdenfors, Harper, and Lewis; and it allows for a unified proof of those theorems, from weaker assumptions about belief revision. This leads to a proof of McGee's thesis that iterated conditionals do not obey modus ponens.
I am extremely grateful to Vann McGee and Robert Stalnaker for teaching me about conditionals and for their advice about this paper. I have benefited from discussions on these issues with many other people, including Horacio Arló Costa, Richard Bradley, Rachael Briggs, Sylvain Bromberger, Walter Dean, Branden Fitelson, Alan Hájek, Ned Hall, Hongwoo Kwon, David Makinson, Rohit Parikh, Agustín Rayo, Hans Rott, Susan Schweitzer, Paul Weirich, and Malte Willer.