I should note that I'm not a formal student of philosophy and haven't studied it in any serious depth. I just like logic, and logical fallacies. I like to spot them, and I like to debate using them, primarily doing so in the (up until now) presumed belief that they improve my arguments and that, wherever a fallacy exists, so too does an invalid argument. That essentially: bad logic = bad argument.
I recently, however, came across The Fallacy Fallacy, which threw my knowledge and presumptions of what logic is upside down. What that Wiki page seems to be saying to me is that even where a claim is argued with fallacious logic, the claim itself is not necessarily wrong. I can certainly understand the reasoning behind this, but then this makes me question what the purpose of logic even is. Why employ it, if you can't use it to definitively prove to your opponent that his argument is false?
If you point out a fallacy in your opponent's argument, and they counter with a "not necessarily" in the form of the Fallacy Fallacy, where's the usefulness in logic at all? I was always under the impression that logic, as one of Russell's a priori knowledge, is a baseline of truth from which the truthfulness of all other truths can be judged, and that as a baseline, it can always be used as a yardstick. Is this not the case? Or am I just misunderstanding what the Fallacy Fallacy is?