I think, therefore I am, therefore I think?

So I'm watching my fellow students, and I notice how thoroughly most of them depend on one another for their sense of self vindication. I see it in their facial expressions. I see it in the way they dress (alike). I see it in the way they talk to one another without any attempt at being genuine. And I take solace in the fact that I am not so dependent upon others. That I define my actions and my desires. And this leads me to a strange question: how is it that I define myself? What I mean is: how can anything possibly define itself? I think I've been duped.