Abstract

Reasoning with indicative conditionals, i.e., with statements such as 'If the weather is bad, then the plane will be late', constitutes a significant part of ordinary reasoning. How are we to proceed in the logical treatment of ordinary language arguments involving indicative conditionals? In particular, is standard formal truth-functional sentential logic applicable to these conditionals, and if so, under what circumstances? This dissertation first examines two sharply contrasting theories proposed in response to these questions. One of them is the dominant view, primarily identified with H. P. Grice and Frank Jackson, which defends the traditional truth-functional treatment of indicative conditionals and also endorses the application of formal logic to them. The other theory, upheld primarily by Ernest Adams, claims that the formal truth-functional logic is inapplicable to indicative conditionals and that their proper treatment requires a special probabilistic logic. Through a critique of both of these theories, I show that these extreme approaches are defective and unsatisfactory. I argue that the main benefit of having such philosophical theories of indicative conditionals can be achieved at a much lower cost by what may be called a common sense account of indicative conditionals. The common-sense account rejects the idea that indicative conditionals in their 'true logical form' are truth-functional material conditionals. It nonetheless endorses the applicability of formal truth-functional logic to ordinary conditional reasoning. On behalf of common-sense account, I argue that the two issues, the assumption of truth-functionality of indicative conditionals and applicability of formal truth-functional logic to them, do not rise or fall together.