PROB'ABILISM (Lat. probabaismus, a barbarous technical word, from proba&elis, prob able), in Roman Catholic theology, means the doctrine regarding the use of so-called opinioni" in guiding the conscience as to the lawfulness or unlawfulness of any particular action. The word came prominently into discussion in the 17th c., and seems now fully accepted as a technical name. As the ground of the doctrine, it is assumed that, in human actions, absolute certainty is not always attainable tts to their lawfulness or unlawfulness. Short of this certainty, the intellect passes through the stages of "doubt" and of "probability." In the former, it is swayed between conflicting views, so as to be unablq, to decide, or even to approach toward deciding, what is true. In the latter, although there is a conflict of views, yet the reasons in their favor are not so equal that the intellect cannot see preponderating motives in favor of the truth of one or of the other. Moreover, in the conflict of views, another element will arise, as to their comparative "safety," that is, the greater or less danger of moral culpa bility which they- involve; and this greater or less moral "safety" of a view may, or may not, coincide with its greater or less "probability." The doctrine of "probabil ism" is 'founded upon these distinctions; and it presents itself in four different schools, all of which agree in professing that it it is lawful, in certain cases, to act upon opin ions which are merely "probable." Opposed to all these four, is the school of anti probabilisni, which rejects altogether the use of probable opinions, and requires that an opinion shall be absolutely morally certain, in order that it may be lawful to act upon it. The four schools of probabilism arc called: prabctLilism simple, a.qurprobabilisrn., probabillorism (from .probabitior,_ more probable), and tutiorism (from tutior, more safe). The first holds that it is lawful to act upon any probable opinion, no matter how slight its probability. The second requires that the opinion shall be " solidly prob able," but holds that, provided it be really probable, it is lawful to act upon it, even though the conflicting opinion should be equally probable. The third, in the conflict of probable opinions, will only permit us to act on the more probable of the two; but per mits this even when the less probable adverse opinion is the "more safe." The fourth reqUires that in all Cases the more safe opinion shall be followed, even when the less safe opinion is much the more probable. It is commonly said that the system of prob abilism is modern; but this is only true of the discussions regarding it, for the doctrine itself, in some of its form; is as old as the study of ethics, even considered as a moral science. The disputes reerrding it arose with the science of casuistry, when men, in
the 16th and 17th centuries, began to reduce morals to a system. It formed a leading subject of the controversy between the Jesuits and the Jansenists, although it is a great, while it is a very common, mistake to suppose that all the Jesuists were probabilists, and that all the Jansenists were opposed thereto. Very few Jesuists, indeed, were of the school which is chiefly assailed in the Provincial Letters (sec PASCAL), that of prob abilisin simple. Without entering into the history of this very curious controversy, it will be enough to say that the Roman church, while condemning the two extremes—the extreme of anti-probabilism, which excludes all use even of the most probable opinions, and the lax extreme of simple probabilism, which accepts even the slightest probability as sufficient—has left the intermediate opinions for free discussion. The great modern master on the subject is St. Alfonso da Liguori, whose system may be described as a kind of practical probabidiorism, in.which, by the use of what are called reflex princi ples, an opinion which objectively is but probable, is made subjectively the basis of ;i cer tain and safe practical judgment. There can be no doubt that the system of probabil ism has been pushed by some individual divines to scandalous extremes; but it is only just to add that these extremes have been condemned by authority in the Roman church; and that, on the other hand, the principles of the higher Roman schools of probabilisin are substantially the same as those of all moralists, whether of the old or of the new schools of ethics.
Protestants, however, and with them some Roman Catholics, reprobate probabilism in all or forms. as a mere scheme for the delusion of conscience and excuse or justification of immorality. They maintain the Scriptural or Christian rule, and the only rule of true morality, to be that no man is entitled on any account to do that of which he doubts whether it is contrary or agreeable to the law of God. Every man must often choose between two courses, as to which is the most expedient; but this they hold to be a totally different thing, It is also urged against the ,probabilists, that they make the authority of doctors, or learned theologians, sufficient justification for a man's doing that which otherwise lie would deem it unlawful to do; asserting that it will keep him safe at the judgment seat of God.