| Summary: | 博士 === 國立中正大學 === 哲學研究所 === 103 === This dissertation deals with two problems of indicative conditionals. First, what is an appropriate interpretation of \Adams' thesis"? Second, what is the property that a "good" inference involving indicative conditionals has? "Adams' thesis" is that the it probability of indicative conditionals is the conditional probability of the consequents given the antecedents ─ schematically:
P(A → B) = P(B|A) (provided P(A) ≠ 0).
Many scholars believe that Adams' thesis is intuitively correct, but they disagree on its exact meaning and why it is correct. This paper argues that Adams' thesis is not only a hypothesis, but also one that can be properly explained and derived by an appropriate semantics of indicative conditionals.
Adams proposes that a good inference should be a it probabilistic sound inference such that the uncertainties of its conclusion cannot exceed the sum of the uncertainties of its premises. However, Stalnaker proposes that a good inference is a reasonable inference such that in every context in which the premisses could appropriately be asserted or supposed, it is impossible for anyone to accept the premisses without committing himself to the conclusion. Adams and Stalnaker both try to capture the property that good inferences involving indicative conditionals have. This paper argues that Stalnaker's account is more plausible than Adams'.
I provides a generalized probability theory of 3-valued indicative conditionals, and given the generalized probability theory it shall be shown that Adams' thesis can be properly explained and derived as a special case when the indicative conditionals under consideration are simple indicative conditionals. The idea is that we need to make a distinction between probability and assertability in order to have a better understanding of Adams' thesis. Then we can make a distinction between assertibility preservation and assertabilitic soundness. In this sense, Adams' probabilistic sound inferences are assertabilitic sound inferences, and Stalnaker's reasonable inferences are assertability preservation inferences. So I conclude that Adams's thesis
should be interpreted as the assertabilities of a simple indicative conditional equals the corresponding conditional probabiliity, and that a good inference is a reasonable inference which has the property of assertability preservation.
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