Should power be based on more than on violence? And if so, on what?

Spinoza thinks people acknowledge the authority of the state for two reasons: out of fear and self-interest. As long as the rules and institutions of the state give most people a feeling of safety and of freedom to pursue their own interests, the state will be justified. 

A state can use intimidation and violence, suspicion and force to keep itself upright, but can still be regarded by its civilians as unjust. 

Spinoza, however, optimistically adds that these states can't uphold themselves for very long without the support of its civilians, and will sooner or later implode or be overthrown.