Probabilism

In theology and philosophy, probabilism (from Latin probare, to test, approve) refers to an ancient Greek doctrine of academic skepticism. It holds that in the absence of certainty, probability is the best criterion. It can also refer to a 17th-century religious thesis about ethics, or a modern physical-philosophical thesis.

In moral theology, especially Catholic, it refers especially to the view in casuistry that in difficult matters of conscience one may safely follow a doctrine that is probable, for example is approved by a recognized Doctor of the Church, even if the opposite opinion is more probable.

This view was advanced by the Spanish theologian Bartolomé de Medina (1527–1581) and defended by many Jesuits such as Luis Molina (1528–1581). It was heavily criticised by Blaise Pascal in his Provincial Letters and by St. Alphonsus Ligourí in his Theologia Moralis, as leading to moral laxity. Opposed to probabilism is probabiliorism (Latin probabilior, "more likely"), which holds that when there is a preponderance of evidence on one side of a controversy one is obliged to follow that side, and tutiorism (Latin tutior, "safer"), which holds that in case of doubt one must take the morally safer side. A more radical view, "minus probabilissimus", holds that an action is permissible if a single opinion allowing that action is available, even if the overwhelming weight of opinion proscribes it.

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