Deductive rationality: When talking about the rationality of a deductive argument, we mean that the argument is valid (the conclusions follow from the premises), and we often also mean that the premises are true.
I disagree with giving rationality this definition. The word you have defined here is “sound”. Having an untrue premise or having an invalid deductive step means that an argument is unsound, but it doesn’t necessarily mean that it’s irrational. An argument may be rational but mistaken, provided (1) the argument was made in good faith, (2) reasonable effort (but not necessarily extensive effort) was put into avoiding mistakes like the one that was made, and (3) the argument is withdrawn when the error is pointed out.
I’m trying to observe what people are using “rational” to mean. I agree with you that an argument can be rational even if the premises are false, as long as they are not known to be false by the arguer.
I’d be more comfortable with leaving the “are not known to be false by the arguer”. In this context, where we are evaluating an argument as rational, it’s simpler to leave off subjective states of the arguer. That saves all sorts of messy complications regarding motive and uncertainty. Making a rational argument from premises that are known to
HughRistik wrote:
I disagree with giving rationality this definition. The word you have defined here is “sound”. Having an untrue premise or having an invalid deductive step means that an argument is unsound, but it doesn’t necessarily mean that it’s irrational. An argument may be rational but mistaken, provided (1) the argument was made in good faith, (2) reasonable effort (but not necessarily extensive effort) was put into avoiding mistakes like the one that was made, and (3) the argument is withdrawn when the error is pointed out.
I’m trying to observe what people are using “rational” to mean. I agree with you that an argument can be rational even if the premises are false, as long as they are not known to be false by the arguer.
I’d be more comfortable with leaving the “are not known to be false by the arguer”. In this context, where we are evaluating an argument as rational, it’s simpler to leave off subjective states of the arguer. That saves all sorts of messy complications regarding motive and uncertainty. Making a rational argument from premises that are known to