Where the numbers come from

The weights and thresholds you've seen so far are just stand-ins — made-up numbers to show how the calculation works.

In practice, machines pick those numbers. The machine starts with rough guesses and adjusts them every time it gets something wrong. Over thousands of examples, they settle into something that actually works.

That's the difference between calculation and learning. It was also the divide between the two camps. The Logic Theorist, the rules-based program from Dartmouth, knew what it knew because someone wrote it down. The Perceptron knew what it knew because it had been wrong enough times to get it right.