Workout controversy about abs?

I'm having a bit of trouble understanding the concept of gaining six pack abs. People say that you need to lose weight and gain muscle to have your abs show. But if i'm losing weight how will I gain muscle. Aren't those two polar opposites?.......Do i need to bulk up first while I'm doing hardcore ab routines, then diet down? Or will my abs show while I'm dieting as long as work them out pretty hard?