“You are what your brain makes you, and your brain is nothing but the generator of your ‘self.’”

Most people know the nature-versus-nurture debate. To understand identity in the broadest sense, replace the “versus” with “and” — it is nature and nurture, because the two aren’t mutually exclusive. By nature I mean what’s largely outside human control — our genetic makeup, how the nervous system develops in the womb, diseases or injuries around birth or later. By nurture I mean the influence of society — the community we’re born into, our parents, our friends, our relationships. As we grow, the brain processes all this while still developing, and it processes it differently for everyone, because every brain is similar yet very different. These intricate interplays — plus the brain’s constant revising of memory and behavior — settle into a sense of identity, especially as the brain stops developing as rapidly after about 26 to 30 years of age, when a more rigid sense of self sets in.

This is also why “the brain is just a computer” undersells it. You can run the same program on very different machines, and in the same way a feeling like pain isn’t identical to one exact pattern of cells — an octopus, or one day perhaps a machine, could feel something while built completely differently. Mental life is fully physical, yet it can’t be flattened into a single tidy description of wiring: real, physical, and not reducible to one neat formula, all at once. (The textbook names for these positions are biological naturalism and non-reductive physicalism, but the plain idea matters more than the labels.) The mystics need you to believe science empties your inner life of meaning so they can sell the meaning back to you. It doesn’t, and you don’t need to buy it back.