In philosophy and logic, contingency is the status of facts that are not logically necessarily true or false.

In philosophy and logic, people draw a distinction between

• possibility: "If it happened, it must be possible" -- If an event happened, it must be a possible event. A possible statement is not necessarily false. A "possibility", such as a coincidence, is either a "contingency", or a "necessity" (but not both).
• contingency: a contingent event is an event which "could have not happened". Each contingent event is also a possible event, but not vice versa. A contingent statement is not necessarily false, but it is not necessarily true either.
• necessity: a necessary event is an event which "could not have not happened". In other words, a necessary event inevitably must have happened. Each necessary event is also a possible event, but not vice versa. A necessary statement is a statement that is necessarily true, such as a tautology.

References

• Michael Shermer, "Glorious Contingency," Metanexus Net [1]