Not the exact wording but the general premise behind it is a fair counter point in any disagreement. When someone is attempting to gain a higher moral authority, bringing up any hypocrisy is a reasonable thing to do. If pointing out hypocrisy is then dismissed, it is reasonable to assume the other person is not arguing in good faith and therefore should no be taken seriously.
A hypocritical and dishonest interlocutor can still make a valid and sound argument. An ad hominem, whether Tu Quoque or otherwise, remains fallacious.
Whether you’re being called immoral by Person A or B doesn’t change the facts. Person A may be a bad person, they may not be the person you want to hear the argument from, but that doesn’t change that they’re right.
In propositional logic you only address one prong or aspect at a time. So using my example you could say yes, I am immoral for kicking puppies, but then by your logic, so are you. That wouldn’t be an ad hominem because you aren’t trying to invalidate their argument with your personal attack/logical argument.
Correct yes, I can see there are two ideas here. We both agree immorality is independent of conversation and no matter what happens in the conversation it will not make the immorality untrue. The point I am trying to articulate may be more whether or not it is appropriate for someone who is simultaneously kicking puppies to point out how immoral it is that I am kicking puppies, while refusing to acknowledge the immorality of their own puppy kicking from a social point of view. Thoughts?
Not particularly. Depends on the subject matter. For instance, a politician might be critical of current campaign finance laws being too lax, but still take advantage of said laws. In that situation it wouldn’t be hypocritical to say I want to change X, but until it changes, I’m following the same rules as everyone else.
Or maybe they are a hypocrite, I don’t know. They could be the worst person to raise the argument, but my only point was that it doesn’t invalidate the argument.