Well, I'm going to side with Descartes on this one. I am sure that I exist, since I think.
I am also sure that taking yourself too seriously is a terrible thing, and that everyone, myself included, is an idiot.
I am sure that people are not basically good, but neither are they inherently evil. They are just people, and it is what they do that makes them good or bad. And yes, I did get that from Blood Diamond.
I am sure of a lot of things, but I'm not going to go into detail. My life's philosophy really just boils down to one concept: "You know what? Fuck it. I'm going for it." I haven't had this outlook for very long, and it conflicts with the personality I've had for most of my life, so I still have trouble following it. Still, I'm convinced that it's the best way to go about living.
And that's what I'm sure of.