Probabilism

Probabilism is a doctrine in Catholic moral theology concerning how to act in situations of doubt about the morality of an action. It holds that in doubtful cases a person may follow a course of action that has probable grounds for being morally permissible, even if there exists a more probable opposing opinion that the action is illicit. The essential condition is that the permissible interpretation is supported by a credible authority and is sufficiently probable, allowing practical conscience to proceed without requiring absolute certainty.

Historically, probabilism arose in early modern Catholic debate as a method for resolving moral questions when authorities offered competing interpretations. It became associated with casuistic reasoning within moral theology and was contrasted with stricter or more lax approaches. Variants and related positions emerged, including equiprobabilism, which allows choosing between equally probable opinions, and other tendencies that stressed different balances between obedience, conscience, and practical discernment. The doctrine drew both support and criticism: supporters argued it provided a humane, practical way to guide action amid uncertainty, while critics warned it could foster laxity by endorsing permissibility too readily.

Today, probabilism is studied as part of the history of Catholic moral theology and as an example of early modern appeals to probabilistic reasoning in ethics. It is frequently discussed alongside other casuistic methods such as laxism, rigorism, and equiprobabilism, in discussions of conscience, authority, and moral decision-making.