 Is the idea of an innate self-sustaining quality tenable? Kvanvig and McCann consider a number of possible construals and argue that they are of dubious coherence. They also give an argument with an Edwardsian flavor. A power to perpetuate one’s own existence would be an ability to cause something to occur at a future time, a time at which the exercise of the power would no longer exist. No physical sequence of events could be the basis for such a time-jumping power, since such a sequence would itself depend on a power of this sort. So the power would need to bring about a future effect without the aid of any intervening events to connect them. But nothing that no longer exists can be causally operative, so there can be no such power (Kvanvig and McCann 1988, 42–3).