Prisoners’ dilemmas are notoriously hard to resolve, because they require participants to coordinate and act collectively rather than pursue their narrow self-interests. But in the past week, Democrats seem to have solved theirs. Over the past 72 hours, culminating with Super Tuesday, much of the center-left lane coalesced around Biden, preventing an early and easy knockout win for Sanders. It was a surprising outcome, and one that suggests Democrats have learned some valuable lessons from the bruising interparty contests of recent presidential nominating contests.