Thinking has always been an ethereal thing. It is the most private of human activities, and while the expression “I know what you’re thinking” is part of the lingua culturae, it is a bold-faced lie. Notwithstanding crypto-keys and blockchains, the only truly protected storage place in the universe – at least for now – is the thought-swarm deep within our respective skulls.
Brains themselves are fascinating stuff, and no one is quite sure what’s in there. This is important, since a vessel of chemicals and tissue generating a cluster of electrical activity is one thing, but that which we call consciousness is quite another. Physicist/Neuroscientist Paul Nunez wrestled with this, building a foundation of scientific facts with which to construct some reasonable theories. Science also warns us, he notes, that some things are fundamentally unknowable.
Philosophers, who spend considerable time thinking about thinking, have had a lot to say about the subject. One of the most influential philosophical works, Discourse on Method (1637) by René Descartes, not only gave us the Cartesian coordinates that we scientists have come to love, but also introduced the discipline of Methodic Doubt. Doubting things methodically led René to the conclusion that he could not doubt his own existence since after all he was the one doing the doubting. The coup de grâce for self-doubters was the legendary “Cogito, Ergo Sum”, aka “I Think Therefore I Am.”