Cybernetics: or Control and Communication in the Animal and the Machine
Machine, animal, and mind all steer by feeding their results back as causes.
A ship's steersman doesn't plot the perfect course once and walk away — he watches, sees how far he's drifted, and nudges the wheel, again and again. Wiener saw that machines, animals, and even societies all steer themselves the same way.
The idea, unpacked
At the heart of the book is one loop, called feedback. A system measures how far it is from where it wants to be, and uses that gap to decide its next move — then measures again, and corrects again. A thermostat does it with temperature; your hand does it with the distance to a cup; a government does it with the gap between a policy and its result.
Wiener's radical claim was that this loop — not the flesh or the metal it's made of — is what produces purposeful behaviour. A machine that corrects itself toward a goal is doing the same thing as a living creature reaching for one. From that single idea he built a science, and named it cybernetics, from the Greek word for "steersman."
Where it came from
Norbert Wiener was a former child prodigy and an MIT mathematician. During the Second World War he worked on aiming anti-aircraft guns at planes that dodged and weaved — which meant predicting where a moving, self-correcting target would go next. That problem, of a system reacting to its own past, never let him go.
Afterwards he pulled the threads together with two collaborators — the Mexican physiologist Arturo Rosenblueth and the engineer Julian Bigelow — with much of the thinking done in Mexico City. In 1948 he published the result as a difficult, wide-ranging book, and gave the new field its name. To his own surprise, it became a bestseller.
Why it mattered
Before Wiener, an engineer building a controller, a physiologist studying a reflex, and a telephone engineer fighting noise on a line had no shared language. Cybernetics gave them one — feedback, signal, noise, information — and showed their problems were versions of the same problem. It also delivered a hard practical lesson: feedback that corrects too aggressively, or acts on information that arrived too late, doesn't merely fail — it swings into wild oscillation. Wiener noticed that this is exactly what a damaged nervous system does when a reaching hand shakes around its target.
A shower you can't get right
Think of an unfamiliar shower. The water's too cold, so you crank the tap hot; but the pipe is long, so nothing changes — you crank it further; then a wall of scalding water arrives, so you slam it back, and a moment later you're freezing again. You're a feedback loop with too much gain and too much delay, hunting back and forth and never settling. Tame the delay and ease your corrections, and you glide smoothly to the right temperature. That swing between overshoot and calm is the whole drama of the tool below.
Where it sits
1948 was a founding year for the information age. The same year, Claude Shannon published his theory of information (also in this Library), and three years earlier John von Neumann had set down the design of the stored-program computer. Cybernetics was the third pillar — the one about control and purpose. Its name eventually faded as its children grew up — control theory, AI, robotics, the whole study of self-regulating systems — but the prefix "cyber-" in words like cyberspace still carries the Greek steersman inside it.
We have decided to call the entire field of control and communication theory, whether in the machine or in the animal, by the name Cybernetics, which we form from the Greek κυβερνήτης or steersman.
the most fruitful areas for the growth of the sciences were those which had been neglected as a no-man's land between the various established fields.
Just as the amount of information in a system is a measure of its degree of organization, so the entropy of a system is a measure of its degree of disorganization; and the one is simply the negative of the other.