>Legitimacy by brute force: someone convinces everyone that they are powerful enough to impose their will and resisting them will be very hard. This drives most people to submit because each person expects that everyone else will be too scared to resist as well.

>Legitimacy by continuity: if something was legitimate at time T, it is by default legitimate at time T+1.

>Legitimacy by fairness: something can become legitimate because it satisfies an intuitive notion of fairness. See also: my post on credible neutrality, though note that this is not the only kind of fairness.

>Legitimacy by process: if a process is legitimate, the outputs of that process gain legitimacy (eg. laws passed by democracies are sometimes described in this way).

>Legitimacy by performance: if the outputs of a process lead to results that satisfy people, then that process can gain legitimacy (eg. successful dictatorships are sometimes described in this way).

>Legitimacy by participation: if people participate in choosing an outcome, they are more likely to consider it legitimate. This is similar to fairness, but not quite: it rests on a psychological desire to be consistent with your previous actions.