I am? Quote me.
You mistake what ad-hominem, as a bias, is. It is a characteristic of an argument or reaction that is focusing on the person making the arguments, rather than the arguments themselves; the validity of an argument is independent of the person making that argument. Anybody modifying the credibility of an argument because of its source is engaging in ad-hominem. In laymen terms, the term is used to describe an argument against a person, but it is broader than that, as a bias.
The question is not of "appropriateness". Choices you make provide information about you. The more idiosyncratic choices you make, the more information these choices provide.
Yes. But it provides information about the source of an argument, not the argument itself.
His username is evidence that (among other things) forms my opinion of him. I don't see how it can be any different.
Where does your opinion of him, as a person, become relevant? That's the key question.
ad-hominem
I notice you didn't quote me. :-/
Your mistake is that you treat the situation as if I'm attacking some arguments by JEB_4_PREZ_2016. I am not. We are not discussing an object-level issue, we're discussing the consequences of choosing an unusual username.
Where does your opinion of him, as a person, become relevant?
In forming priors about his posts.
To give an example, if I develop an opinion that Alice tends to post incoherent wall-of-text ramblings with zero interesting content, I will stop reading her posts. Or, say, if I observe that Bob ...
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
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