This ebook is an extended Masters thesis (35,000 words) critically evaluating the theories of Ernest Adams and Frank Jackson about indicative conditionals. Adams Hypothesis that the subjective probability of a conditional is equal to the corresponding conditional probability is generally supported, but the author argues that cases against conditional excluded middle also count against Adams Hypothesis. These involve exceptional circumstances, wherein the author argues ‘If A, then C’ and ‘If A, then not-C’ are both assertable. The author uses this to warrant a modification of Adams Hypothesis, one that the author also argues avoids the triviality results of David Lewis. The author supports this modified hypothesis as giving the necessary conditions for asserting an indicative conditional, its “assertibility”, as Jackson has termed it. Rather than supporting Jackson’s explanation of this assertibility, which is in terms of the material conditional truth conditions and the utility of modus ponens arguments, the author introduces his own account of the truth conditions of indicative conditionals. (This is based on there being some ground for the conditional. The condition for a suitable ground is weaker than the usual cotenability condition that similar theories have explored. In many, but not all cases, the corresponding material conditional would suffice as a suitable ground.) Thus, the book argues for (1) a modification of Adams Hypothesis as necessary for the assertion of an indicative conditional, (2) that this modified Adams Hypothesis avoids Lewis’ triviality results; and (3) that indicative conditionals have truth conditions, which are not material, but which in special circumstances permit ‘If A, then C’ and ‘If A, then not-C’ to both be true. These aspects of this 1988 thesis are still novel as of 2013, and relevant to current philosophical investigations of conditionals, although the author does not cover the more recent possible world triviality results.
The author, Dr Peter Eldridge-Smith, became a lecturer in logic and philosophy at the Australian National University.
The author, Dr Peter Eldridge-Smith, became a lecturer in logic and philosophy at the Australian National University.
