Perhaps there is no other knowing than the mere competence of the act. If at the heart of one's being, there is no self to which one ought to be true, then sincerity is simply nerve; it lies in the unabashed vigor of the pretense.
But pretense is only pretense when it is assumed that the act is not true to the agent. Find the agent.
Source: Joyous Cosmology
Contributed by: stumblinguponmoksha