A social system is not just a gathering of people. It does not consist in the interaction between people either. You can find a mere causal interaction between things. What is it then?
1. The double contingency
I defined a system as function to reduce indeterminacy. What makes social systems different from other systems is a special character of the indeterminacy for them to reduce. In order to understand what indeterminacy they must reduce, you have only to imagine how inconvenient it would be without social systems.
Suppose you run into a stranger in an anarchic jungle. Both of you point guns at each other and shout at the same time, "Throw away your gun, and I will throw mine away."
Whether I abandon my gun or not depends on whether the opponent abandons his gun or not, and whether he abandons his gun or not depends on whether I abandon my gun or not. When the selection of both systems thus indeterminately depends on that of the other, the indeterminacy is named double contingency.
2. The paradox of the prisoners’ dilemma
It is the best for both to abandon the weapons and coexist peacefully. But there is no guarantee that the opponent will throw away his gun as he promised, even if I throw away mine. He might monopolize the weapons and enslave me.
The combination of payoff in possible four cases is as follows:
The opponent abandons his gun.
The opponent keeps his gun.
I abandon my gun
I keep my gun.
My reasoning is " Whether the opponent will abandon or keep his gun is indeterminate. But in either case, my payoff will be bigger, if I keep my gun. So, I should keep my gun." But, as this is also his reasoning, neither of the two abandons his weapon.
This is the so-called prisoners’ dilemma. The Soviet Union and US in the Cold War era, both of which hesitated to reduce the nuclear weapons, were caught in the same dilemma.
According to the game theory, the strategy that maximizes the minimum of my payoff, whatever strategy the other player(s) may adopt, is the optimal response. The combination of strategy optimal for any player is called Nash Equilibrium. The paradox of the prisoners’ dilemma consists in that the best judgment sometimes induces each player to select the Nash Equilibrium, although all players know it is not the best.
3. To escape from prisoners’ dilemma
What should the two of you do, then, so as to extricate yourselves from the anarchy and secure your lives? You cannot get out of the dilemma of double contingency by yourselves. So, let’s assume the case where the third appears.
Suppose a common friend appears and, holding pistols in both hands to the two, say, "Throw away your guns in three seconds or I will shoot you. One, two, three!" Then he can make you two abandon the guns. In this case, the third functions as the Government.
When the third is a suspicious alien, he may enslave the two of you, if you abandon your guns. So, you cooperate with the opponent to kill the third, so that the third cannot fish in troubled waters. It makes you have a sense of solidarity. This is the effect of scapegoating.
The third that solves the dilemma of double contingency is called a communication medium. Whether it is a common friend or a common enemy, the communication medium must be equally distant from all players and this same distance makes the communication medium public.
Not all indeterminacy specific to social systems is double contingency. Industry is bound to regulation of bureaucracy, the bureaucracy is bound to the politicians’ orders and the politicians are bound to the industry lobby. This tripartite dependent relation of decision-making is not a mere combination of double contingency. So, let’s use a more comprehensive term than double contingency, "multi-contingency". Now I can define social systems as communication media that reduce the multi-contingent indeterminacy.