Ideas from 'Conditionals' by Dorothy Edgington [2001], by Theme Structure

[found in 'Blackwell Guide to Philosophical Logic' (ed/tr Goble,Lou) [Blackwell 2001,0-631-20693-0]].

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10. Modality / B. Possibility / 8. Conditionals / a. Conditionals

13768

Validity can preserve certainty in mathematics, but conditionals about contingents are another matter

			Full Idea: If your interest in logic is confined to applications to mathematics or other a priori matters, it is fine for validity to preserve certainty, ..but if you use conditionals when arguing about contingent matters, then great caution will be required.
			From: Dorothy Edgington (Conditionals [2001], 17.2.1)

10. Modality / B. Possibility / 8. Conditionals / b. Types of conditional

13770

There are many different conditional mental states, and different conditional speech acts

			Full Idea: As well as conditional beliefs, there are conditional desires, hopes, fears etc. As well as conditional statements, there are conditional commands, questions, offers, promises, bets etc.
			From: Dorothy Edgington (Conditionals [2001], 17.3.4)

10. Modality / B. Possibility / 8. Conditionals / c. Truth-function conditionals

13764

Are conditionals truth-functional - do the truth values of A and B determine the truth value of 'If A, B'?

			Full Idea: Are conditionals truth-functional - do the truth values of A and B determine the truth value of 'If A, B'? Are they non-truth-functional, like 'because' or 'before'? Do the values of A and B, in some cases, leave open the value of 'If A,B'?
			From: Dorothy Edgington (Conditionals [2001], 17.1)
			A reaction: I would say they are not truth-functional, because the 'if' asserts some further dependency relation that goes beyond the truth or falsity of A and B. Logical ifs, causal ifs, psychological ifs... The material conditional ⊃ is truth-functional.

13765

'If A,B' must entail ¬(A & ¬B); otherwise we could have A true, B false, and If A,B true, invalidating modus ponens

			Full Idea: If it were possible to have A true, B false, and If A,B true, it would be unsafe to infer B from A and If A,B: modus ponens would thus be invalid. Hence 'If A,B' must entail ¬(A & ¬B).
			From: Dorothy Edgington (Conditionals [2001], 17.1)
			A reaction: This is a firm defence of part of the truth-functional view of conditionals, and seems unassailable. The other parts of the truth table are open to question, though, if A is false, or they are both true.