Knowledge becomes actionable through the agency interface—the beliefs we hold and the frameworks we use to make sequential decisions. Belief is the settled state that guides action—the cessation of doubt that permits commitment. Agents maintain belief states—probability distributions over possible world states—updated through observation and action. Rationality is bounded—cognitive actors satisfice rather than optimize, relying on frameworks that compress an intractable world into actionable models. The mind operates through a dual architecture: System 2’s deliberate reasoning produces judgments that, through repetition, compress into System 1’s automatic intuitions. Effective agency depends on maintaining belief systems both stable enough for action and adaptable enough for learning.