The misuse of certain words in the rationalist community drives me up the fucking wall, and so in this post I shall explain the correct usages.
Precommitment. Precommitment is the use of a commitment device to ensure that you will face severe negative consequences from making certain choices you wish to commit to not making. Beeminder is a precommitment device, because if you don’t reach your goals, you will have to pay money.
Does Not Mean The Same Thing As: “Commitment”. If you stood up in front of your friends and family and solemnly promised not to divorce, you’re committed; if you’re going to pay two-fifths of your income in alimony, you’re precommitted.
Cooperate/Defect: These terms are used in a wide variety of different game theory situations, but the one most popular among people who aren’t game theoreticians is the Prisoner’s Dilemma. In the classic Prisoner’s Dilemma, two prisoners are separated. If one snitches on the other, he will get a reward and the other will be imprisoned; if both stay silent, they will both go free; if both snitch, they are both imprisoned. Many situations can be modeled as Prisoner’s Dilemmas.
Does Not Mean The Same Thing As: “Prosocial”/”antisocial”. If you wear an “I cooperate on prisoner’s dilemmas” shirt, I’m going to get worried that you’re planning on starting a wage-fixing cartel.
Schelling Point: The point on which people will naturally converge in the absence of communication. For instance, if you have to meet a stranger in NYC without communicating with them, you will probably meet them at noon at the information booth at Grand Central Station.
Does Not Mean The Same Thing As: “The place at which we agreed to meet each other through explicit communication.” If you communicate with each other, it is not a Schelling point.
Also Does Not Mean The Same Thing As: “Schelling fence“, which refers to the place where people draw the line on a slippery slope. For instance, in the US, the Schelling fence about government intervention in free speech is “no fighting words, obscenity, libel/slander, true threats, or child porn”.