We often find competition and cooperation at the same time. Think of a football game. During the game, one team is competing against the other, but each member of the team must cooperate with his teammates. Otherwise, they would lose the game however skilled every individual player might be.
While advocating competition, we must not forget cooperation. In modern society, cooperation is especially necessary because except for a few craftsmen and artists, most work is fulfilled with and through other people. In many cases, we can not achieve anything if there are only competition and no cooperation.