13764
|
Are conditionals truth-functional - do the truth values of A and B determine the truth value of 'If A, B'? [Edgington]
|
|
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 [Edgington]
|
|
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.
|
2854
|
Prescriptivism says 'ought' without commitment to act is insincere, or weakly used [Hooker,B]
|
|
Full Idea:
Prescriptivism holds that if you think one 'ought' to do a certain kind of act, and yet you are not committed to doing that act in the relevant circumstances, then you either spoke insincerely, or are using the word 'ought' in a weak sense.
|
|
From:
Brad W. Hooker (Prescriptivism [1995], p.640)
|
|
A reaction:
So that's an 'ought', but not a 'genuine ought', then? (No True Scotsman move). Someone ought to rescue that drowning child, but I can't be bothered.
|