Audi's contributions to epistemology include his defense of "fallibilistic foundationalism". Audi has expanded his theory of justification to non-doxastic states, e.g. desires and intentions, by developing a "comprehensive account of rationality". A mental state is rational if it is "well-grounded" in a "source of justification". Justification can come "directly" from experience (e.g. perception) or "indirectly" from other mental states that are themselves justified. Rationality is relative to a person's experiences, so what is rational to believe for one person may be irrational to believe for another. Audi has also developed an account of "autonomy", which he characterizes as the "self-governing power" to bring reasons to bear in directing one's conduct and influencing one's propositional attitudes. "Self-legislation" is necessary but not sufficient for autonomy since it lacks the power to govern by itself. Autonomy involves responding to reasons in a principled way by "endorsing commitments" to projects and practical principles.