Point I. Notion of the System, State of the Question, Diverse Systems

I. Notion of a system. A moral system, as it is taken here,¹ is a general principle by which someone who, after due inquiry, is not certain of the honesty of an action or omission, forms a practically certain conscience for himself. The sense of this definition will be clear from the very state of the question now to be explained.

¹ A moral system taken in the broader sense is the whole science of morals constructed in suitable order through its first principles.

II. State of the question. The question concerns doubts which proximately and directly regard the morality of an action, but not other doubts. Therefore:

1. The question does not concern doubts which proximately and directly regard, for example, the validity of an act, the matter of the sacraments, etc. In these doubts, and generally whenever some good is to be obtained or some evil is to be avoided which does not depend on the dictate of conscience, the safer part or opinion, as it is called, must of itself be followed. Therefore this must of itself be chosen: first, in the conferral of the sacraments; second, in danger of one's own spiritual or temporal harm that must necessarily be avoided, such as, for example, danger of life or of formal sin; third, in danger of another's spiritual or temporal harm that must necessarily be forestalled. Hence, for example, a physician is held to apply the medicine which seems safer to him. I said "of itself," because if necessity presses and the safer part cannot be brought into practice, it is licit, for example in the ministration of a sacrament, to use even a thinly probable opinion (St. Alphonsus, I, 42-53). Moreover, all these things are developed more suitably and more abundantly in the respective treatises of Moral Theology and, as we said, do not pertain to the state of the question treated here.

2. But the question is what general principle there is by which, in a theoretical doubt about the honesty of an action, a practically certain conscience is obtained. In other words, we inquire to what extent he acts licitly who, after the truth has been inquired into, is himself not certain of the morality of an action or omission; or who himself is not certain whether or not there exists a law which prohibits the action or omission, or whether the opinion which favors the law, or that which supports liberty, is true. It is said:

a) To what extent he acts licitly. Therefore it is not asked what someone can or ought to impose on others in doubt, but to what extent the doubter himself acts licitly.

b) After the truth has been inquired into; since, if due inquiry has been omitted, it is not licit to have recourse to a reflex principle.

c) Himself. Hence we do not inquire to what extent someone licitly places an action about whose objective morality others are not certain; but we investigate to what extent he licitly places it who himself is not certain of its objective morality.

d) Is not certain, that is, he is either in a state of doubt about the objective morality of an action, or opines that it is objectively dishonorable.

Therefore we seek a certain and universal rule by which, when two opinions about the morality of an action concur, one of which favors the law and the other liberty, it may safely be judged when in practice it is right to follow the part of liberty and when we must fulfill the law.

Moreover, the proposed question is answered in different ways by different persons; and indeed these different answers, as was already said above, constitute the different moral systems.¹

¹ There are some who think that there is no need of a moral system. But those who think thus are mistaken and themselves unconsciously admit some system. For it is certain that very many doubts occur about the objective morality of actions. Hence the adversaries themselves must answer, and do answer, the question to what extent it is licit to act in doubts of this sort. Now that which they give as an answer to the question is their moral system.

III. Diverse systems. Seven are enumerated, namely: absolute Tutiorism, mitigated Tutiorism, Probabiliorism, Equiprobabilism, Probabilism, Laxism, and the System of Compensation.

Absolute Tutiorism states: It is not licit for me to follow an opinion favoring liberty unless this is certain to me; or: The law obliges me unless I am certain that it does not exist.

Mitigated Tutiorism teaches: It is not licit for me to follow an opinion favoring liberty unless this is most probable to me; or: The law obliges me unless I hold it as most probable that the law does not exist.

Probabiliorism states: It is not licit for me to follow an opinion favoring liberty unless this is more probable to me; or: The law obliges me unless I hold it as more probable that the law does not exist.

Equiprobabilism professes: In doubt about the making of a law, it is licit for me to follow an opinion favoring liberty, provided this is equally or almost equally probable to me as the opposite opinion favoring the law. But in strict doubt about the cessation or fulfillment of a law, the law is to be observed.

Probabilism contends: It is licit for me to follow an opinion favoring liberty, provided this is truly probable to me, and this even if the contrary opinion is certainly more probable to me; or: The law does not oblige me provided I hold it as truly probable that it does not exist, and this even if I hold it as more probable that it does exist. And these things hold even if the law certainly existed, provided it has probably ceased or has been fulfilled.

Laxism admits the use even of a thinly probable opinion.

The System of Compensation teaches that in doubts the safer thing is to be followed unless a relatively grave inconvenience excuses.¹

Absolute Tutiorism,² mitigated Tutiorism, and Laxism³ are commonly rejected; Probabiliorism, Equiprobabilism, Probabilism, and the System of Compensation are sustained. We admit Equiprobabilism, which system indeed we now undertake to prove and to vindicate from objections.

¹ Thus Laloux, De actibus humanis; Potton, De theoria probabilitatis; Boisdron, Theorie et systemes des probabilites; Prummer, Manuale Theol. Mor., t. I, n. 351; McDonald, The Principles of Moral Science, p. 254. The system of Cardinal d'Annibale deserves special mention; in his Summula Theologiae moralis (I, nn. 262 and 264), relying only on the principle of possession, he gives his vote, with respect to doubt about the existence of a law, rather to Probabilism; and with respect to doubt about the cessation or fulfillment of a law, to Equiprobabilism. That system could be called the System of Possession, or Possessionism.

² Alexander VIII struck down the thesis: "It is not licit to follow an opinion, or among probable opinions the most probable one."

³ Innocent XI condemned this proposition, the third: "Generally, while, relying on probability either intrinsic or extrinsic, however slight, provided one does not go beyond the limits of probability, we do something, we always act prudently."