RAMSEY’S TEST, ADAMS’ THESIS, AND LEFT-NESTED CONDITIONALS

Adams famously suggested that the acceptability of any indicative conditional whose antecedent and consequent are both factive sentences amounts to the subjective conditional probability of the consequent given the antecedent. The received view has it that this thesis offers an adequate partial explication of Ramseyʹs test, which characterizes graded acceptability for conditionals in terms of hypothetical updates on the antecedent. Some results in van Fraassen (1976) may raise hope that this explicatory approach to Ramseyʹs test is extendible to left-nested conditionals, that is, conditionals whose antecedent is itself conditional in form. we argue that this interpretation of van Fraassenʹs results is to be rejected. Specifically, we provide an argument from material inadequacy against a generalization of Adamsʹ thesis for left-nested conditionals.