 By contrast, QBists adopt a subjectivist or personalist interpretation of probability, in quantum theory as elsewhere (see entry on  interpretations of probability,  §3.3). This makes the Born Rule of quantum theory not a law of nature but an empirically motivated norm of rationality a wise agent should follow in addition to those whose violation would render the agent’s degrees of belief incoherent. As usually formulated, the Born Rule specifies probabilities for various possible measurement outcomes given a quantum state: But QBists also adopt a subjectivist or personalist interpretation of quantum states.