Logic, disingenuosness, and ethics?

Which is the most, or least (whichever way you prefer to put it), moral?

To not support an argument whose conclusion you agree with because its premise is bad?

To not disagree with a bad argument whose conclusion you support?

Note that disingenuousness in this context would be implicit, where someone might perceive your challenge to their argument as evidence of you not being committed to the same conclusion.

Logic, disingenuosness, and ethics?

Both options seem to be the same...

1. Good conclusion, bad premise

Stance to not support (but not express disagreement)

2. Good conclusion, bad argument (= bad premise)

Stance to not disagree (but also not agree)

So are you asking whether it is better to either not disagree or not support the same argument?

Logic, disingenuosness, and ethics?

It might depend on the system of ethics to which you appeal. In a utilitarian system, the ends are the focus, so bad, weak, or false premises would not be of as much import so long as the conclusion (ends) met the requirements of the ethical system.

But, a rational person can hardly claim to maintain rationality and at the same time support an invalid or weak argument. The claim of reason and rational argument is to steadfastly follow wherever reason leads, even if it leads to a conclusion which you would prefer not to reach.

The problem with a utilitarian system is that it is difficult to gauge if you've met the threshold for the requirements of the system. Such systems don't have rigorous axioms as a foundation, but rather only guidelines that can't possibly envision every conceivable circumstance. Reason and rational argument, on the other hand, have rules and axioms that guide inferences with rigor. Of course, evaluating the actual truth of any premise in this world is another matter altogether - for any system.