Probabiliorism

Probabiliorism is an ethical and theological doctrine concerning the certainty required to act when facing doubt about the morality or legality of a course of action. It is primarily associated with Roman Catholic moral theology. The core principle of probabiliorism states that if an action is subject to doubt regarding its permissibility (i.e., whether it is lawful or unlawful), one must act in accordance with the more probable opinion. This means that if there is a more likely opinion that the action is permissible, one may proceed with that action. Conversely, if the more probable opinion is that the action is unlawful, one must refrain from it.

This doctrine emerged as a response to earlier ethical systems like laxism, which allowed acting on a mere possible opinion, and rigorism, which demanded absolute certainty or the opinion of the majority of theologians. Probabiliorism seeks a middle ground, requiring a solid foundation for the chosen opinion, rather than just any possibility. The "probability" in probabiliorism is not necessarily statistical probability but rather a moral or theological certainty based on sound reasoning, the authority of theologians, or established theological principles.

The practical application of probabiliorism involves weighing the arguments for and against the permissibility of an action. If one opinion is clearly more persuasive, better supported by theological reasoning, or favored by a greater number of reputable theologians, then that opinion is considered more probable. Acting on this more probable opinion is then deemed morally licit, even if some doubt remains. This doctrine has been influential in shaping moral decision-making within certain theological traditions.