I may be wrong on this, but I think arguing over the internet has officially displaced baseball as America’s official past time. Whether you’re a lurker, a white knight, or this guy,*
you should know how to argue correctly, even if all you want to do is break the rules and troll.
Therefore, let me point you to this link from io9.com. Here you will find six short animations that should help you not only identify, but also avoid, logical errors. Watch them, learn them, and good luck out there.
*This image is from the brilliant web-comic XKCD, by the way. But the original image was not working, so I used this one.