- (Premise) I know that if I am human, I am mortal.
- (Premise) If I know something, it's true.
- So, it is true that if I am human, I am mortal.
- (Premise) If something is true, it has truth value.
- So, that if I am human, I am mortal has truth value.
- (Premise) That if I am human, I am mortal is a conditional.
- So, some conditionals have truth value.
Continuing:
- (Premise) I know that it is wrong to torture the innocent for fun.
- So, it is true that it is wrong to torture the innocent for fun.
- So, that it is wrong to torture the innocent for fun has truth value.
- (Premise) That it is wrong to torture the innocent for fun is a moral claim.
- So, some moral claims have truth value.
Another argument:
- (Premise) No one is morally to blame for violating a moral rule that no one could know.
- (Premise) One is only to blame for violating a moral rule.
- (Premise) Someone is to blame for something.
- So, someone is to blame for violating a moral rule.
- So, some moral rule can be known.
- (Premise) Necessarily, only truths are known.
- So, some moral rule can be true.
- (Premise) Necessarily, anything that is true has truth value.
- So, some moral rule can have truth value.
This is, of course, a problem for non-realist accounts of conditionals and morals.
5 comments:
I suppose I accept premiss (2), but I have no idea how to go about justifying it. Do you think something can be said in its favor or is it a take-it-or-leave-it starting point?
Well, there is an argument from authority. In all the discussion of Gettier problems and the old justified-true-belief story about knowledge, the claim that truth is required for knowledge seems to be the least controversial.
I'm not sure what non-realist accounts of conditionals are (do you have in mind assertion conditions rather than truth conditions?). But this is a problem for non-realist accounts of morality only if you mean by 'realism' that moral judgments take a truth-value. But that is an extremely weak form of realism. Subjectivist accounts of morality admit that moral judgments take a truth-value.
Right: the kind of realism I have in mind here is just the having truth values kind.
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