Philosophical discussion of cybernetics and control theory

hand on the tiller, exist in a world of energy and forces, as does the helmsman. The weak forces that control the rudder are as real and physical as the strong forces that toss the ship. If we shift our cybernetics perspective from the ship to the helmsman, the pressures on the rudder become a strong force of muscles controlled by the weak signals in the mind of the helmsman. These messages in the helmsman’s mind are amplified into a physical force strong enough to steer the ship. Or instead, we can zoom out and take a large cybernetics perspective. We might see the ship itself as part of a vast trade network, part of a feedback loop that regulates the price of commodities through the flow of goods. In this perspective, the tiny ship is merely a messenger. So, the distinction between the physical world and the information world is a way to describe the relationship between the weak and the strong. Wiener chose to view the world from the vantage point and scale of the individual human. As acyberneticist, he took the perspective of the weak protagonist embedded within a strong system, trying to make the best of limited powers. He incorporated this perspective in his very definition of information. “Information,” he said, “is a name for the content of what is exchanged with the outer world as we adjust to it, and make our adjustment felt upon it.” In his words, information is what we use to “live effectively within that environment.” *> For Wiener, information is a way for the weak to effectively cope with the strong. This viewpoint is also reflected in Gregory Bateson’s definition of information as “a difference that makes a difference,” by which he meant the small difference that makes a big difference. The goal of cybernetics was to create a tiny model of the system using “weak currents” to amplify and control “strong currents” of the real world. The central insight was that a control problem could be solved by building an analogous system in the information space of messages and then amplifying solutions into the larger world of reality. Inherent in the motion of a control system is the concept of amplification, which makes the small big and the weak strong. Amplification allows the difference that makes a difference to make a difference. In this way of looking at the world, a control system needed to be as complex as the system it controlled. Cyberneticist W. Ross Ashby proved that this was true in a precise mathematical sense, in what is now called Ashby’s Law of Requisite Variety, or sometimes the First Law of Cybernetics. The law tells us that to control a system completely, the controller must be as complex as the controlled. Thus cyberneticists tended to see control systems as a kind of analog of the systems they governed, like the homunculus—the hypothetical little person inside the brain who controls the actual person. This notion of analogous structure is sometimes confused with the notion of analog encoding of messages, but the two are logically distinct. Norbert Wiener was much impressed with Vannevar Bush’s Digital Differential Analyzer, which could be reconfigured to match the structure of whatever problem it was given to solve but used digital signal encoding. Signals could be simplified to openly represent the relevant distinctions, allowing them to be more accurately communicated and stored. In digital signals, one needed only to preserve the difference in signals that made a difference. It is this distinction and signal coding that we commonly use to distinguish “analog” versus “digital.” Digital signal encoding was entirely compatible with cybernetic thinking—in 33 The Human Use of Human Beings (Boston: Houghton Mifflin, 1954), p. 17-18. 125 HOUSE_OVERSIGHT_016345