If/when someone (who somehow found their way onto your flist though you can't remember exactly how) continually posts things that you take issue with, which makes the stronger and more lasting impression? -- to argue it out with them every time so that it at least gets cogently challenged, or to unfriend them so that they can tell that your tolerance has run out with them?
Personally, I tend to prefer arguing to just walking off and cutting people out, and I only shake the dust off my feet with people when I'm fairly certain that nothing is to be gained or bettered by continued interaction -- because, to me, deliberately stopping talking to someone implies that they are personally not worth the effort or bother of talking to, and it's hard for me to give up hope in communication having some persuasive effect.
( Pointedly-oblique rhetorical wanderings -- caveat lector... )
Regardless, there's the ramble of my thoughts as framed obliquely.....hope there's something to be found in it.
_
[* Aristotle, for one...though I've been known to say a few things myself in the ethical/moral realm.]