What's the Next Word

What this book is about

In the last few years a machine has arrived and settled into everyone's hand. It writes letters in Bangla, explains sums, drafts an essay before breakfast. Some people say it is nearly human. Others say it is just a calculator. Both are wrong, and both are wrong for the same reason — nobody has told anyone what the machine is actually doing inside.

This book opens the inside up. No picture-book fairy tale, and no "it just somehow happens" either. Everything needed is counted on these pages, worked out on these pages, and checked on these pages. Sit down with a notebook and a pen and you can get nearly every number in this book out for yourself. Not one formula falls from the sky — each is born on the page where it first appears.

It ends where the honest books end: with what the machine cannot do. Confident falsehoods, why it is bad at arithmetic, what it learned from what was written — and why your exam is still your work.

What is inside

• Start by counting: how the phone knows, counting marks, counting pairs of words
• Where counting gives up — an ocean of empty cells, and writing a word as numbers
• One small neuron: weights, the sum, the red pen mark, and the weight moving a little
• Layer upon layer, and which word matters now — attention, arrived at rather than announced
• What it cannot do: does it really understand, confident falsehoods, why sums defeat it
• The people who built the road — Pāṇini and al-Kindī, Ada Lovelace, Turing's imitation

game, that summer at Dartmouth, the perceptron and two winters, and a paper from 2017

• Two experiments to try, every rule in one place, exercises, a glossary and a quiz