Cooperation can lead to successes; however, it also leads to a lack of your own creativity and willingness to stand out from the crowd. Often, this is not a good thing, and can lead to problems, but just as often it is a good thing.
Cooperation is the act of working with other people, particularly on a larger project than one can handle on their own with a high chance of success. On large projects, it is generally good to attempt to cooperate with someone else; otherwise you can quickly become overwhelmed and that can cause the project to fail miserably. You should probably cooperate with others whenever you can on large scale projects, and sometimes small scale projects.
There are also times where it is better to act as an individual instead of cooperating with others on certain projects, particularly creative projects and very small scale projects. If you do choose to cooperate with others on those types of projects, it should probably only be one or two other people at most. Too many people can quickly make it harder for you to express your creativity, or it becomes harder to manage all those people that don’t necessarily need to be there. It can really make a mountain our of a molehill.
Sometimes it is good to cooperate with others. These times generally occur on large scale projects. In these cases a better result can be achieved by working with others. That said, there are still times where having extra people is a hindrance to you, especially if it is something creative (like art for example).