Another response to Matt, drawn from his comments here.
In my opinion, the defining feature of life is its uncertainty.
I empathize with this idea of uncertainty. I believe we all need a good dose of it to have a healthy outlook on life, but let me play devils advocate if I may. Where do we draw the line with our uncertainty? It is one thing to be uncertain about the creation of the universe, but it is quite another to be uncertain about the our perception of reality as revealed by our senses. Where does one draw the line? One could easily make the argument that since our perceptions are really nothing more than electrical charges bouncing around in the tissue between our ears, then how can we trust the reality they reveal to us? You are left with a strictly uncertain view of life. But for most of us that is nonsense. We come to trust our senses and accept that what they reveal to us really is true. How far then can we we take a more trusting outlook? How much of reality can we really discover? What have we discovered in 5,000 years of somewhat recorded human history? Of that, what can be trusted when held up against the light of recent human findings?
What we need to be careful of is that in this search for truth, we don't simply find what we are looking for. That is one of the main reasons I keep seeking opinions different than my own.
When we were children we believed what we were told to believe. As we grow into adults we gradually realize that we are not all playing from the same sheet of music. We were all told many different stories. Some of us react with anger to this realization, others with denial, but in the end we all seem to think it's important to try and make sense of it. Should we be certain of our findings? I'm not so sure. Am I certain of my position? I don't know that I can say yes to that. At the same time though, I'm staking my life on the assumption that it's truth. Is that certainty?