 A proposition was regarded as credibilis or opinabilis if it could legitimately be accepted as one’s opinion. The underlying criteria were often the same as for probabilis. Propositions which did not satisfy the respective criteria were called inopinabilis or improbabilis, and deserved to be rejected by rational and responsible epistemic agents. This meant that improbable propositions ought not to be taken for true or accepted as a premise for action, but not necessarily that they must be regarded as  false.[10]