Can science explain the self?

The big idea: Every thought you've ever had came with a flicker of activity in your brain.

So here's the question science pushes on us: could your whole inner life — every feeling, memory and choice — really be nothing more than chemistry in your head?

This is the promise of cognitive science: to explain the self the way we explain the weather — as a physical system following physical rules.

Hold onto this: Keep two things apart: that brain activity goes with every experience (clearly true), and that brain activity is all there is to an experience (the big claim in question). The first is data; the second is a bet.

Start with the boldest version of the scientific answer.

Reductionism: you are your brain chemistry: Reductionism about the self says: love is a rush of certain chemicals, a memory is a pattern of connections, a decision is neurons firing. Nothing is left over. The self isn't an extra thing floating above the brain — it just is the brain doing its work, the way a wave just is water moving. If that's right, then in principle a complete brain-science could explain everything about you.

Checkpoint — reductionism: In one line: the self is nothing more than the brain's chemistry — no leftover 'you' on top. Hold that — the next section asks whether the chemical story really captures everything.

Even people who agree the brain is involved suspect a purely chemical story misses something.

The 'what it's like' problem: Imagine a scientist who knows every fact about how your brain handles the colour red — every wavelength, every neuron, every chemical. But she has been colour-blind her whole life and has never actually seen red. Does she know what seeing red is like? It seems not — there's a fact she's missing that no amount of chemistry gave her. Philosophers call this felt, inside quality of experience qualia. If qualia are real and the chemistry misses them, then science hasn't captured the whole self.

Go further — higher-level insight: Notice the shape of the reply that saves reductionism. It doesn't have to deny the feeling — it can say the 'gap' is a gap in our knowledge, not in the world: the feeling really is brain activity, we just don't yet see how. Naming the difference between 'a gap in reality' and 'a gap in what we understand' is a top-band move.

Checkpoint — the gap: In one line: science explains the brain brilliantly, but 'what experience is like from the inside' is exactly the bit it seems to leave out.