Almost the whole modern period from the opening of the seventeenth century is occupied with the controversy about the right system of moral theology. Modern research has confirmed the historical accuracy of the account of the origin of this dispute which Fr. Antony Terill or Bonville prefixed to his work "Regula Morum," published in 1676. Fr. Terill, S.J., was a learned and acute theologian who taught theology at the English College of the Society at Liège, now represented by Stonyhurst and St. Beuno's. Besides his "Regula Morum" he published another work, "De Conscientia Probabili," in 1668. He was a good and conscientious man and had ample means of knowing the facts to which he testifies. According to Fr. Term, until about the year 1638 practically all Catholic theologians of all schools accepted and taught probabilism. The only exception was the not very notable Italian Jesuit Comitolus, who published his "Responsa Moralia" in 1608. Comitolus taught probabiiorism and attributed the doctrine of probabilism quite falsely, to what he calls the shameful lapse of Armilla. The opinion of Comitolus passed almost unheeded, and there was peace and comparative harmony in the schools of morals. This peace began to be broken when the friends of Jansen were planning the publication of his famous book "Augustinus." The first of the five propositions which were extracted from that book and condemned by Innocent X in 1653 asserted that there were some laws of God which could not be observed even by the just, do what they would, and that God did not give grace to enable them to observe these laws. This heretical and blasphemous proposition, which made God a tyrant who gave orders which He knew could not be obeyed, was altogether out of harmony with the prevailing system of moral theology, and its Jansenist supporters began to attack probabilism in order to make an opening for their own rigoristic doctrine. According to Caramuel, who was at Louvain at the time and who wrote a book against them in 1639, they began to teach covertly that the use of probabilism was something new; that he who leaves the safe way and follows probabilism can not but be condemned by God; that opinions which are styled probable among us are not probable with God. The war between probabilism and antiprobabilism had broken out, a war conducted with the greatest heat and passion for two hundred years, and not even yet quite ended. The Louvain Doctors after the condemnation of "Augustinus" by the Holy See retaliated by issuing their propositions against probabilism in 1655. The strategy was the same as led Döllinger and Reusch to publish their work on "Moralstreitigkeiten," after the definition of Papal Infallibility. The war, however, was soon carried into France where Jansenism had won the support of a few proud spirits of the highest intellectual gifts. Among these Pascal was pre-eminent, and he struck the hardest blow which probabilism has ever sustained by publishing his "Lettres Provinçiales" in 1656. The book is unfair and misrepresents the doctrines which it attacks, but its wit and style gave it at once a place in the classical literature of the world. It was condemned by Alexander VII at Rome in 1657, but by non-Catholics it is still regarded as the last word on the subject of Catholic and especially Jesuit moral theology. Although the rise of Jansenism was the occasion of the outbreak of war, there were other causes also which contributed to the heat of the combat. Fr. Terill laments the disastrous laxity of opinion on moral questions which was conspicuous in many of the probabilist authors of the day. Many of these wrote books, not to expound the truth, but to attract attention to themselves and acquire notoriety. The means they employed for this purpose was the ventilation of new opinions in morals. By making use of the weak argument from similar cases they broached hitherto unheard of doctrines which were industriously collected by the casuists. The fact that somebody or other had said in his book that an opinion was probable and that it had not been condemned by the Holy See was held sufficient to merit for it a place among probable opinions in moral theology. Fr. Terill, himself a strenuous defender of probabilism, raised his voice against the inrush of laxity. He did much by his writings to improve the theory by stating and explaining it more accurately than had been done hitherto. He insisted that in order to be accepted as a rule of conduct it was not sufficient that an opinion should have some slight degree of probability, or should only be probably probable; it should be well grounded, seriously and solidly probable in the judgment of experts, of men of virtue and learning. The common method of proving probabilism by saying that one who acts on a probable opinion acts prudently, was objectionable on the theoretical side, and Terill improved it by making use of reflex principles, such as, "A doubtful law is not promulgated and can not bind." This eminent English Jesuit thus tried to stem the tide of laxity in an age of immorality by stating the theory of probabilism more accurately and limiting its use to its proper sphere. Other theologians with the same laudable end in view threw probabilism overboard altogether. This was especially the case with the theologians of the great Order of St. Dominic. A member of this Order had first formulated probabilism, as we have seen, and, as Salon testifies, other Dominicans were conspicuous as being the first to accept and teach it. The most famous Dominican theologians of the time, Ledesma, Bañez, Alvarez, Ildephonsus, and others were all probabilists. No antiprobabilist Dominican was heard of till the year 1656. In that year a general Chapter of the Order was held at Rome and all the members were urged to adopt the stricter opinion in morals. From that time onward the chief Dominican theologians have almost without exception been probabiliorists. Among others are the well-known names of Mercorus, Gonet, Contenson, Natalis Alexander, Concina, Billuart, and Patuzzi, the adversary of St. Alphonsus Liguori.
From the strife of parties different moral systems began to emerge. Jansenist rigorism, which required direct moral certainty against the law to justify a departure from its observance, and which was not satisfied even with a most probable opinion in favor of the lawfulness of an action, was condemned by Alexander VIII in 1690. Laxism, which was satisfied with even a slightly probable opinion as a rule of conduct, had been condemned by Innocent XI in 1679. Probabiiorism and probabilism together held possession of the field. At the beginning of the eighteenth century a few theologians such as Amort, Rassler, and Mayr, defended equiprobabilism. This system required an opinion in favor of liberty to be equally probable with that in favor of the law before allowing it to be used as a rule of morals. It would not allow any one to follow an opinion in favor of liberty which was distinctly less probable than that which favored the law.
These three systems still have their defenders, and the last has acquired strength from the adhesion to it of St. Alphonsus in the later portion of his life. St. Alphonsus Liguori is recognized as the Doctor of moral theology as St. Thomas is of dogmatic. By his writings he drove out of the Church the last remnants of rigorism, and firmly established that common doctrine in moral theology which it has been the aim of the author to expound in these volumes. In spite, however, of general agreement, there are some points of detail which are still matter of controversy among moral theologians.
St. Alphonsus was ordained priest in 1726 when he was thirty years of age. He had been taught the probabiliorist system of morals, but in the course of fifteen years of study and experience in the confessional he came to the conclusion that the system was false and harmful to souls. He then adopted probabilism, and mainly using recognized probabilist authorities, especially of the Society of Jesus, whom he acknowledged to be his masters in this branch of learning, he composed his chief work, the "Theologia Moralis." The first edition appeared in 1748, and a second and much enlarged edition was issued in 1753. In 1755 St. Alphonsus published an elaborate dissertation on probabilism in which he proved the doctrine and refuted the objections commonly brought against it. He became bishop of St. Agatha of the Goths in 1762, and published another dissertation in which he appeared to adopt a new system of moral theology. While admitting that it is lawful to follow a solidly probable opinion, he denied that when in favor of the law there is an opinion which is certainly and notably more probable than its opposite, this latter can be really and solidly probable. The question is one of fact. If this proposition be considered from the practical and concrete point of view, its practical truth may be admitted, and St. Alphonsus probably understood it in this sense. Furthermore, it may be admitted that the doctrine has its value in deciding when an opinion is solidly probable or not, and this was what St. Alphonsus intended. He wished to exclude laxism from his system, and he invented this formula for the purpose. Moderate probabilists secure the same end by stressing solidly when they require a solidly probable opinion for a lawful rule of action. Considered theoretically and logically, the formula of St. Alphonsus is open to attack, as it is not true that a greater probability, even if notable and certain, does necessarily deprive the opposite opinion of all solid probability. On this point there is still some difference of opinion between simple probabilists and equiprobabilists, but the dispute has little to do with practical morals. The dissertation of St. Alphonsus was not inserted in the "Moral Theology" of the saint till it reached its sixth edition, and his change of formula made little change in the doctrine of his work. It remained substantially what it always had been -- a great work on moral theology written by a moderate probabilist.
Moral theology is still what St. Alphonsus left it. There is general agreement in the schools, a common doctrine which all accept; it only remains to apply this to the social and political conditions which we see growing up around us.
In this modern period of moral theology the sufficiency of attrition without any strictly so-called initial charity on the part of the penitent as a proximate disposition for the remission of sin in the sacrament of Penance may be considered as established. The changed conditions in our modern capitalist society have had their effect on moral questions, for morality must always take account of altered circumstances. Perhaps the chief result in this direction is that a practical solution has been attained of the long controversy about the lawfulness of taking interest for a loan of money. The lawfulness of the practice is now admitted; the only moral question is concerning the amount which may be exacted. The doctrine of the just price is applicable here; money, like other commodities, has in our modern capitalist society its just price.