Where the numbers come from

Every weight and threshold you've seen so far was made up, a stand-in chosen to show how the calculation works.

So where do the real numbers come from? Nobody sets them by hand. The machine finds them itself.

It starts with random guesses. It tries an example, sees how wrong it was, and nudges each number a little in the direction that would have helped. One example barely changes anything. But after thousands of them, the numbers settle into a set that actually works.

That is the line between calculation and learning. A calculator is handed its numbers by a person. This machine is handed nothing. It arrives at its own numbers by being wrong, over and over, until it stops being wrong.

That was Rosenblatt's whole bet, the one the rules camp doubted: that a machine could find the answer on its own, instead of being told it.