Thought processes are based on a bunch of neurons in your brain firing in sequences to produce some output patern that is categorized as either thought, or behavior. Logic is the use of thought to attempt to correlate ideas with each other based on similarity, causation, effect, and possible outcomes. Since it's only based on the firing of neurons, we can't really be certain in any way that logic/reasoning/all thoughts are related in any way to reality. Logic isn't necessarily right. Thus, the old Cogito Ergo Sum bit might not mean anything. It certainly seems that there's a correlation between existing, and being able to do anything, but this correlation can't really be proven without assuming it's true (IE assuming you and the universe around you exist). I don't buy it. I'm not here, I'm not writing this, and you're not reading it. I'm just a figment of my own non-existant imagination.