i like where you are going with this, but only two?
the human brain is the embodiment of the term, cruft. layer after layer added on over millions of years of evolution.
that doesn't even include interaction with our environment. which includes, but is not limited to, chemicals, natural and artificial, in our air water and food, variations in light and other parts of the em spectrum affecting our cycles, parasites and symbiotes from microbes on up chemically making us do things of which we often are not even aware. thinking is hugely complex and so substantially affected by external factors that sometimes i wonder if it is wise to believe we can separate the internal thinker from externalities we think about. i don't want to forget about thinking about thinking. when trying to take into account external factors in thinking about our thoughts the whole thing becomes so complex that i don't quite know where to go from there. i do think we have to start somewhere and i applaud the crack you're taking at it. keep going. the benefits we reap from self reflection and examination can only improve us. thanks for the inspiration.