In general, I think understanding the concept of deciding whether or not an argument was good or not. I think part of the reason I do not understand the concept is that there is so much “repetition”. False premise, false conclusion. False premise, true conclusion. Everything just starts to look the same, if you ask me. Then there’s plausibility of the claim which basically if the claim is believable or not. If someone came up to you and told you that the sky is yellow, the you would come to the conclusion that the premise presented is not plausible and then false. The there is the conclusion follows from the premise. There has to be a connection between the two. You cannot just say that Nancy is a girl. She is a bitch. There is no real connection. If you say Nancy girl. She says a lot of mean things about people. She is a bitch. Then there is a connection between the premises and the conclusion.
http://www.jimpryor.net/teaching/vocab/validity.html