AIM Framework glossary
Prior Belief
Canonical definition
Prior Belief, denoted P(H), is the degree to which a Hypothesis H is held to be true before Bayesian Updating: the probability Conscious Cognition assigns to H at the start of an updating cycle, before the current Evidence is incorporated. It is a matter of degree, not a verdict, a low value is H held to be probably false, a high value H held to be probably true, so a single Prior Belief spans disbelief to Belief on one scale. It is fully general as to subject matter: a prior Belief about tomorrow's weather, a diagnosis, or a legal question is a Prior Belief in the same sense as one about the source of one's own wanting. The degree to which H is held true is not whether H is true (Truth is correspondence with the world, independent of credence); a Prior Belief may sit at any degree and still misjudge H. Like the Prior it carries, it is index-relative: each cycle's Posterior Belief becomes the next cycle's Prior Belief, naming a position in the updating chain, not a fixed start. The Prior Belief over the source of a motivation (the distribution across the A, I, and M source Hypotheses) is the motivational specialisation named Source Belief.
Explanation
A prior Belief is how strongly you already lean toward a Hypothesis being true, about anything at all, before the next piece of information arrives. It is a dial, not a yes/no: near the bottom you are holding the Hypothesis to be false, near the top true, and most Beliefs sit between. Leaning toward true is not being right; the dial records only your confidence, which can be high and wrong. It is where your thinking starts this round and the residue of every round before, so it biases how you read what comes next. When the question is where your own wanting came from, the prior Belief is a Source Belief, especially prone to skewing toward "my desires are authentic," the ratchet at the heart of the Confabulation Cascade.
Epistemic status
Framework-general epistemic term. The motivational specialisation is Source Belief.