DR. McDONALD’S “PRINCIPLES OF MORAL SCIENCE”

This book deserves a welcome as an honest attempt to grapple with the difficulties of moral science. How great those difficulties are is generally recognized, and by none more fully and freely than by those who have tried to overcome them. Modern theories in history and science have directed renewed attention to the fundamental problems of ethics, and it is fitting that readers who are interested in the subject should be able to study the Catholic answer to those problems in the mother tongue. Students of theology, too, will benefit by being able to consult an English author, who goes over the ground rendered so familiar to them by our Latin text-books. There are many such works published in other modern languages, but as yet the English language is singularly deficient in them.

These, however, were not the reasons that induced Dr. McDonald to publish his essay. He tells us in his preface that while it is his main object to explain and defend the traditional system of morals which has been taught for centuries in the Catholic schools, yet he claims to have arrived at some important conclusions which are not to be found elsewhere. “If it were otherwise,” he says, “I should not have thought of writing or publishing.”

In the course of teaching moral theology, he noticed a considerable difference between the general principles formulated in the treatises on Human Acts, Laws, and Conscience, and the special conclusions arrived at afterwards when treating of the particular ’ virtues. These special conclusions he regards as the true rules of moral conduct, and as furnishing the material for that wider synthesis which forms the substance of the earlier and fundamental treatises. Hence these special conclusions should furnish a test for the validity and accuracy of the general principles laid down in the treatises on Human Acts, Law, and Conscience.

I quite agree. A general principle of morals which breaks down when applied to particular cases does not deserve to rank as a principle. It makes a pretense of being a rule of conduct, while in practice it furnishes no guide to conduct at all. If, then, the contention be true, that some of the general principles of the fundamental treatises of moral theology as found in our text-books do not harmonize with the doctrine on special virtues, all moralists will welcome the demonstration of its truth, and will be thankful for an accurate and plain statement of the general principles which should be substituted in place of the old.

No theologian would pretend that the common doctrine found in our text-books on the fundamental treatises of moral theology has reached its final, definitive, and perfect stage. Progress is still possible, and no doubt progress will be made in the method of presenting the doctrine, in the enunciation and ordering of the principles, and in other ways. And if we are to advance, some one must attempt the task, some one must act as pioneer of the way. This is another reason why this book deserves a welcome. But if the advance is to be on secure lines, it is no less necessary that the critic should be on the look out, and should perform his task honestly and fearlessly.

This is what I propose to do in this article. For the great bulk of the book, inasmuch as it presents in a good English dress the common doctrine of the Catholic schools, I have nothing but praise and a sincere welcome to offer. It is with two or three of those special conclusions at which Dr. McDonald has arrived, and which he says are not to be found elsewhere, that I propose to deal. I may say frankly at the outset that I do not agree with them; and so I find my place among those many students of morals, who, as he tells us in his Preface, the author foresaw would question and deny the success of his attempt in the direction of novelty.

In the remarks which I have to make I shall strive to be as impersonal as possible; I shall look at the doctrines criticized from the purely objective point of view, and I am sure Dr. McDonald will not resent the friendly and honest criticism of a fellow-worker in a field of knowledge, as difficult as it is interesting.

A good practical test of the morality of an action is the effect which it produces. Adultery, theft, selfishness, are seen to be morally wrong because of the evil consequences which they produce. What, however, is to be said of the moral quality of an action which produces both good and bad effects? The administration of chloroform renders the subject insensible to pain, but it also deprives him of the use of reason for the time being; craniotomy preserves the mother but it kills the child. How are we to judge of the morality of such actions as these which produce effects of opposite moral quality? Dr. McDonald discusses and rejects the test which is commonly given in our text-books of moral theology. He translates the principle as formulated by Father Lehmkuhl thus : —

It is lawful to perform an action which produces two effects, one good, the other bad,—provided (1) the action, viewed in itself is good or at least indifferent; (2) the agent does not intend the evil effect, but only the good (it is well to add in some cases: and provided there is no danger of subsequent evil consent or intention); (3) the good effect is produced as immediately as—that is, not by means of—the bad; (4) and there is a sufficiently weighty reason for permitting the evil effect. (Page 149.)

He then proceeds to criticize the principle in this manner : —

There is not one of these four conditions that does not present difficulties to my mind. Let us take them in order :—

(1) ‘‘The action’’—that is, as I understand it, the external action—‘‘viewed in itself, must be good or at least indifferent.’’ But is not the whole question at issue this: how is one to know whether this action is good in itself, when its effects are good as well as evil? You tell me that it is to be considered lawful—which is the same as good— if, among other things, it is good in itself; and I do not see how this makes me a whit the wiser. (Page 149.)

Dr. McDonald misunderstands the principle which he impugns. The whole question at issue is, of course, the morality of the action which produces both good and bad effects. We wish to know whether the administration of chloroform, for instance, is a good action; whether craniotomy is lawful; whether, to take a third example given by Dr. McDonald, it is lawful to walk to the fields in summer time for the sake of exercise and relaxation, in spite of the fact that at each step we crush the life out of many lowly forms of sentient being. The principle tells us that such actions will be morally good if certain conditions are verified. The first is that the action viewed in itself, that is, apart from its effects, must not be bad. This is not the whole question at issue, as Dr. McDonald asserts that it is; the question at issue is, whether the action remains good, even though it produce an evil effect. We can examine the morality of the action apart from its evil effect, and this is what the principle tells us to do. Thus, in the last instance quoted from Dr. McDonald, it is possible to walk in the fields without destroying sentient life at all, or at least we may conceive of its being done; the question is, whether it remains a lawful action in summer time, when it cannot ordinarily be done without destroying animal or insect life. The action of walking in the fields, even in summer time, is ethically good, or at least indifferent, viewed in itself, apart from consequences, and thus it satisfies the first condition laid down in the principle. This is a distinct step towards the solution of the question concerning the morality of walking in the fields in summer time; when we have got thus far, we are something more than a whit the wiser. For, if the question were whether I may tell a lie to save another’s life, or in other words, whether a lie is lawful when it produces a good effect in spite of its also producing a bad one, the question would at once be settled in the negative by the application of our principle; the first condition would not be satisfied, because to lie is bad in itself. Dr. McDonald proceeds : —

(2) ‘‘The agent must not intend the evil effect, but only the good.’’ But, according to the doctrine laid down in the last chapter, the question of intention or subsequent consent does not arise. We want to test whether a certain external action, regarded in itself, is morally good or bad; and I think I have shown that external acts, as such, do not depend for their morality on any concomitant or subsequent act of the will. (Page 149.)

Dr. McDonald misunderstands the second condition as seriously as he misunderstood the first. We are not concerned here with the mere external action regarded in itself. We want to know whether it is lawful to walk in the fields in summer time. The action is regarded as a complete human act, therefore as a voluntary act, as one issuing from free will, therefore as necessarily informed by a certain intention, an intention which may be good or bad. To walk in the fields in order wantonly to destroy sentient life is a bad action, because informed by a vicious intention ; to walk in the fields for recreation, or to till them, is good. With a view to settling whether in a concrete case walking in the fields is a good and lawful action, the principle lays down the condition that the intention must not be bad. This has nothing to do with the disputed question whether the intention can change the nature of the external act.

The third condition is: “The good effect must be produced as immediately as — that is — not by means of the bad.”

Criticizing this condition Dr. McDonald asks: “Is this universally true?” I answer, Yes, if in the circumstances the evil effect remains evil, for we must not do evil that good may come of it. To amputate a diseased leg in order to save life is not evil, and so the example does not show that the condition laid down is false, though the Doctor seems to think that it does. And though he here implies that when chloroform is administered, the good effect is obtained through the evil, he does not prove it; and even if that were proved, he would still have to show that to produce unconsciousness by administering chloroform when there is good reason for it, is evil. Dr. McDonald refers us to another work of his for a criticism of the terminology of the fourth condition, and then briefly subjoins:

The ‘‘weighty reason’’ required is the good effect which must also be produced by the action. . .. Now it is not much addition to one’s sum of knowledge to be told that an action is wrong which does not produce any but an evil effect; nor does it help much to be informed further that the good effect produced must bear some proportion to the evil. (Page 150.)

I shall have something to say to this further on.

After his polemic against the principle of a double effect, Dr. McDonald inquires whether the distinction between direct and indirect causality may not serve as a basis for the test which ought really to be applied in all cases of mixed results. He rejects this suggestion, but in his discussion on this point he falsifiés the meaning of the distinction as commonly used by theologians, and confounds it with the distinction between per se and per accidens. When theologians treat of the lawfulness of direct and indirect killing, the distinction does not merely refer to the direct or indirect causality of the external act; it has special reference to the intention.¹ Dr. McDonald, indeed, rules the question of intention out of court, but such is not the practice of moral theologians when they discuss the questions with which the Doctor is here occupied, and inasmuch as those questions are concerned with human acts, acts necessarily informed by some intention, not with the merely physical external acts of the body, as he seems to suppose, it is difficult to see the reason for abstracting from the intention.

¹

Finally, the Doctor proposes a principle of his own in substitution for the principle of a double effect. He states it thus: —

“That is said to be intended directly in any action which is intended primarily and for its own sake. Its correlative is indirectly, which is said of that which is intended only by reason of another and as it were accidentally. . . . In morals, he directly intends homicide who commands it; indirectly, he who posits some cause of it, such as drunkenness, from which it follows.”—Lexicon Scholasticorum Verborum.

An external action is to be considered morally good, even though it should produce a bad as well as a good effect, provided (1) it does not subordinate a being which by nature is not to be subordinated; and (2) the good effect produced is sufficient to compensate for the bad. (Page 158.)

The chief reason why Dr. McDonald wrote his book was, it will be remembered, to remedy a defect in other authors. As he says, just before the statement of his new principle: —

I am convinced that when they come to practical work our theologians retain their sound common sense and forget or neglect the general principle which they were at such pains to establish at an earlier period, when treating of what I may call the metaphysics of moral science. (Page 157.)

Unless I am very much mistaken this procedure will be necessary in the case of Dr. McDonald’s own principle. In fact, he himself virtually acknowledges as much. On two conditions, he says, an external action will be morally good, even though it produces a bad as well as a good effect; first, it must not subordinate a being which by nature is not to be subordinated. But which are those beings which by nature are not to be subordinated? Unless this is known, it will not be possible to apply the general principle. It will only be a general rule of conduct in so far as it enables us to decide the morality of particular cases. However, Dr. McDonald confesses that there is no general rule that can be given.

It is reasonable to ask [he says] how one is to decide whether and how far any being is by nature subservient to another. I know of no general rule that may be applied; one has to go through the different essences in nature, examine their circumstances, compare them, and then decide whether and how far they are independent or subservient. (Page 163.)

To go through the different essences in nature, examine their circumstances, and compare them, is the work of a theologian, and not an easy task even for him; so that there will be no slight difficulty in discovering whether the first condition is verified in a particular case.

The second condition is, that the good effect produced should be sufficient to compensate for the bad. Now this seems identical with one of the conditions ordinarily required by theologians in the common statement of the principle of a double effect. “ There must be a sufficiently weighty reason for permitting the evil effect,’ says Father Lehmkuhl, quoted above. Dr. McDonald would seem to have forgotten his criticism of that condition in the former connection: “Nor does it help much,” he wrote, “to be informed that the good effect produced must bear some proportion to the evil” (page 150). If it did not help much there, I cannot see how it can help much here. Furthermore, he confesses that here also no general rule can be given for deciding whether the good effect is sufficient to compensate for the bad (page 165). The circumstances must be balanced in particular cases, certain allowances have to be made; what those allowances are is a question which the writer on ethics has to face when he comes to treat of the separate virtues; in doing this he must draw liberally on the light supplied by other practical sciences. The work, evidently, is not child’s play; in any case the result will not help us much.

I am afraid practical moralists will not find Dr. McDonald’s principle of much use. It is as difficult to decide whether the conditions laid down are verified, as to decide the moral quality of the external action.

Moreover, unless I seriously misunderstand the Doctor’s meaning, the principle is inadequately formulated. As laid down it would allow actions to be done which are certainly wrong. For example: I am in poverty, and I have the opportunity of relieving my wants and those of my family by stealing £5 from a wealthy neighbor. This action produces a good and a bad effect; it relieves my want, though to be sure it also deprives my neighbor of a sum which he will hardly miss. The action will be lawful, according to Dr. McDonald, on condition that it does not subordinate a being which by nature is not to be subordinated, and if the good effect is sufficient to compensate for the bad. Both these conditions would seem to be verified by my action. I subordinate money to human wants, as by nature it should be subordinated; the good effect is out of all proportion to the bad. The money in my hands goes to feed my family, in the hands of its owner it would go to feed his dogs.

I must confess I do not see why this is not a legitimate application of Dr. McDonald’s principle; it is with the purpose of excluding such applications of the principle of a double effect that theologians require, as a first condition, that the action in itself should be good, or at least indifferent; but Dr. McDonald rejects that condition as involving the whole question at issue.

Besides the principle of a double effect, Dr. McDonald adversely criticizes the common doctrine about penal laws. However, his chief objections to that doctrine are not new; they appear to me to have been abundantly answered by such classical writers on Law as Suarez and Laymann. Besides, I should very much doubt whether the Doctor’s rather strict views on this point are at all general in the land of potheen. It will be more interesting to pass on to his criticism of the fundamental principle of Probabilism and Equiprobabilism alike, the principle that doubtful laws do not bind the conscience.

This principle is capable of being understood in several ways. All theologians hold that doubtful laws bind in some sense. Thus, in a case of practical doubt as to the existence of a law I am bound to make due inquiry, and I am not at liberty to act until I can, directly or reflexly, form a certain conscience on the question. Dr. McDonald strives to show that there is no general law which obliges one in doubt to acquire certainty as to the rightness of his action before he proceeds to act. (Page 199, sqq.) But surely the law which forbids us to act with a doubtful conscience binds us to do this. Quod non est ex fide peccatum est. If I doubt whether it be a day of abstinence or not, and eat meat without taking any pains to form a certain conscience, I commit a sin, and that whether it be a day of abstinence or not. For the very fact of my eating meat in spite of my being doubtful whether it is not forbidden by the Church shows that I am prepared to break the law of the Church about abstinence, and this is a sinful disposition, which is externated by my eating meat, which act therefore is a sin, whether there be a prohibition to eat meat on that day or not. This explains why it is always a sin to eat meat with a doubtful conscience, even when the doubtful law does not exist. How would Dr. McDonald explain this on his assumption that doubtful laws bind directly and of their own force? A law which does not exist cannot bind. Dr. McDonald’s argument, therefore, seems destitute of force. The fact that the sin committed by one who acts in doubt is of the same species as would be the sin committed against the doubtful law if it existed, does not show that a doubtful law binds the conscience; it only proves that there is a general law which prescribes that we must form a certain conscience before we act.

Moreover, a doubtful law may in a certain sense be said to bind after due inquiry has been made, and the doubt cannot be directly solved. If, after forming my conscience in this case I act against the law which really exists, I commit a material sin, but I am excused from formal guilt. All theologians, I think, also admit this. The doubtful law is said in such cases to bind imperfectly, in actu primo, not perfectly and in actu secundo. Dr. McDonald hardly seems to admit the validity of this distinction as applied to the obligation of law, and almost violently attacks the defenders of probabilism, who use it in the exposition of their system. His remarks, however, show that he has misunderstood its history and meaning.

I do not know [he writes] when or by whom this distinction between first and second act was introduced into treatises on the binding force of laws. St. Alphonsus took it, apparently, from Cardinal Gotti; and the curious in such matters may inquire whether the learned Cardinal is responsible for first transferring the terms in question from the treatises on actuality and activity, where they were found originally and where they serve some purpose, to treatises on law and its obligation, where they are almost without meaning. (Page 206.)

But surely treatises on law and its obligation are treatises on actuality and activity. This appeared so evident to Suarez that he took it for granted at the beginning of his great treatise on Laws.²

² Lib. I., c. iv., n. 3.

There can be no objection, then, to using the distinction, in actu primo and in actu secundo, of the different phases in which we may consider the obligation of laws. Such classical authors as Suarez and Sylvius used it in this sense long before Gotti wrote. The very term obligation is derived from physical activity, as St. Thomas explains in a celebrated passage: —

The command of some ruler stands in relation to binding in voluntary matters by that mode of binding which can befall the will, just as bodily action stands in relation to binding bodily things by the necessity of coercion. But the bodily action of an agent never induces necessity in another thing except through the contact of the coercion itself with the thing upon which it acts; hence no one is bound by the command of any king or lord unless the command reaches the very person to whom it is given; and it reaches him through knowledge. Hence no one is bound by any precept except through knowledge of that precept; and therefore one who is not capable of knowledge is not bound by a precept, nor is anyone ignorant of a precept of God bound to fulfill the precept, except insofar as he is bound to know the precept. But if he is not bound to know it and does not know it, he is in no way bound by the precept. Just as in bodily things a bodily agent does not act except through contact, so in spiritual things a precept does not bind except through knowledge.

It is difficult, then, to see what ground Dr. McDonald has for objecting to a distinction which is in accord with the nature of things, and which has been consecrated by the usage of centuries in the schools. His subsequent remarks, however, show that he has seriously misunderstood the meaning in which the distinction is used.

Now, when those theologians [he writes] who defend probabilism by calling in aid this distinction between first and second act,—when they say that a law which has been promulgated, indeed, but is not yet known for certain to a particular subject, binds only in first act, what do they mean? What can they mean? The first act of the law began to be, as we have seen, when the legislator’s jurisdiction began; and all the laws which it is possible for him to make, even though he has and never had the least intention of making them, bind in first act by the very existence of this power. That is the only philosophical meaning attaching to the term ‘‘first act,’-—a power to operate, as distinguished from an operation. (Page 207.)

There is a certain note of triumph about this, and it would be unfair to leave the reader to suppose that Dr. McDonald is unaware that the usage of theologians is against him. The facts are against him as well. We are here concerned not with the jurisdiction of the legislator, but with the obligation, binding force, activity, of the law. The jurisdiction of the law-giver is in first act while it remains in habitu; it comes into second act when it is used to make a law. The law just made but not yet in force is in first act; when it comes into operation, when it begins to bind, it is in second act. This may be illustrated and at the same time proved by a brief quotation from Sylvius : —

8 De Veritate, q. 17, a. 3.

The controversy [whether the natural law binds all men generally, even boys and the insane] seems capable of being removed by saying that this law binds absolutely everyone in some manner, namely by at least an imperfect obligation and in first act, although it does not bind everyone by a perfect obligation and in second act.

We have learned from St. Thomas, quoted above, that a law binds perfectly and fully only through the knowledge of the subject. A law is a rule framed to direct the actions of rational beings, who are guided by reason and will; in order then to guide them the rule must be known. A law is also a rule given to a community of men, not to an individual, so that in order to bind, it must be authoritatively brought to the knowledge of the community as such, or in other words, it must be promulgated. Leges tunc instituuntur cum promulgantur. Laws then do not exist in their full and perfect being until they are by promulgation brought to the certain knowledge of the community. This is the teaching of St. Thomas, and, I think, of all theologians. Yet it is a truth which is sometimes ignored or forgotten by Dr. McDonald. Thus, on page 196, we read : —

4 In Iam IIae q. 94, a. 4.

Moral theologians argue as if a law could not exist objectively whenever there is reasonable doubt as to this objective existence; either because, in that case, it could not have been sufficiently promulgated ; or because laws can bind only those who have knowledge of their existence. These arguments, however, are so feeble that I can hardly regard them as being intended to prove,—what, nevertheless, is the only thing they could be conceived to prove,— that the existence of law, objectively considered, is affected by doubt in the mind of the subject.

When moral theologians use these arguments to show that a doubtful law does not impose a perfect obligation, they are not dealing with a merely negative doubt, nor with the merely subjective doubt of some particular individual; they mean a positive doubt resting on solid grounds, a doubt resting on an objectively probable opinion, which makes it objectively doubtful whether the law has been promulgated. For if it had been promulgated there could not be such ignorance of its existence among the community. In such circumstances the law has not been sufficiently brought to the knowledge of the community, and so it is wanting in one of its essential elements. This is what St. Alphonsus and other theologians mean when they say that a law which is not promulgated does not bind, or is no law; and, that a doubtful law is not sufficiently promulgated. If Dr. McDonald had always borne this in mind, he would not have written such passages as the following: — Of themselves, therefore, doubts in the mind of those who are subject to a law, prove absolutely nothing as against the existence of the law; and instead of laying down the principle, doubtful laws do not bind, we should say, It is doubtful whether laws bind in cases of doubt. A doubtful law binds or does not bind according to the truth or falsehood of either of the opinions about its existence or its meaning. (Page 197.)

Nor is it a question of subjective responsibility or freedom therefrom, as the Doctor seems to suppose : —

The question of responsibility is thus raised: when and why is one responsible for an act which is out of order materially? Is it necessary that one should be subjectively certain of the material deordination? Or may a man be held responsible even though he is merely in doubt subjectively? The advocates of probabilism commonly maintain that there can be no responsibility as long as subjectively the agent merely doubts of the objective deordination. Is this proved? Is it true? (Page 198.)

Probabilists maintain that a probable opinion against a law does not merely affect individual responsibility, it affects the objective binding force of the law. However, I never came across a probabilist who maintained what Dr. McDonald says they commonly do maintain. This will be clear from what has been already said, and it is not necessary to comment on the three or four pages of argument with which the Doctor proves the falsity of a thesis which no probabilist, that I know of, would defend.

In spite of his objections to the maxim: Doubtful laws do not bind — Dr. McDonald allows that sometimes it is true. A doubtful law does not bind, he says, “whenever observance of such a law is the greater of two or more evils or dangers of which one has to be faced or accepted.” (Page 205.)

There is, of course, a well known principle of moral theology which prescribes that in case of a perplexed conscience, when we must choose one of two evils, there is an obligation to choose the less. Dr. McDonald goes further than this and seems to propose the principle as the one universal solvent of all cases of doubtful conscience. He writes: —

Doubtful laws are to be observed whenever the evil or the danger to be apprehended from not observing them, is considered greater than any that would result from observance. This, accordingly, of all the principles yet proposed for the resolution of practical doubts, is the only one that a scientific moralist can harmonize with the other principles of his science. (Page 205.)

Further on he gives us an algebraic formula for the principle: —

When once you have become convinced that in cases of doubt the golden rule is to follow the course which is apprehended as least dangerous, the next question to be considered is, how quantities of danger are to be measured and compared so as to find out which is the least. It seems to me that they may be measured according to the following general rule: The quantity of the evil that is feared, multiplied by the probability that it will occur,—probability being regarded as a fraction of the unit certainty,— is equal to the amount of danger in any given case. The formula may be stated algebraically thus: D = lp; where D means the danger, l the loss or evil, and p the probability that this loss will be incurred. (Page 210.)

It seems to me that there is no probability that this golden rule will be adopted by moralists for other cases of doubt than those so-called cases of perplexity, in which there is no choice but the less of two moral evils. In one class of cases it would be immoral to apply it. I cannot do better than take an instance given by Dr. McDonald himself: —

Take, for instance, the case of a trades-union rule which is probably inordinate. It is a serious loss to the artizans concerned if the rule should be in order objectively whilst they are not allowed to act on it; and it may also be a serious loss to employers if the men are allowed to act on a rule which, objectively, is a violation of employers’ rights. In this case the dangers are capable of being compared, just as if the question in doubt were one merely of fact. (Page 213.)

Let l be the loss to the artizans and p the probability that it will occur, while l′ represents the loss to the employers and p′ the probability that it will occur. Then by the formula, if

lp > l′p′

the artizans may act on the trades-union rule, which is probably unjust. And so, according to this doctrine, I may do something which is probably unjust to my neighbor in order to avoid a greater money loss to myself. Does Dr. McDonald mean this? Is it sound morality?

In many other cases of doubt, the rule cannot be applied for want of definiteness in the elements of the case, or because the two evils or losses are incommensurable, or too dependent on subjective considerations. I doubt, for example, whether I have said my Breviary. In such cases Dr. McDonald tells us, if I understand him rightly, to estimate the relation of the loss accruing from enforcing a law which does not exist, to that which is caused by not enforcing a law which does exist. The loss accruing from enforcing a law which does not exist in this case is about an hour of my time; but, on the other hand, by saying my Breviary again I gain merit. On the other side of the account by not enforcing a law which does exist I lose spiritual merit, but I gain an hour of time. Dr. McDonald seems to suppose that there is always loss to somebody, the Church or the law-giver perhaps, when a doubtful law is not enforced. This I fail to see. When an adverse custom makes the obligation of a law first of all doubtful, and then removes it altogether, is it not for the public good in the circumstances? Putting this aside, how can the loss of merit be measured in this case? On one supposition I gain merit for saying my Breviary twice in the day, on the other I lose what I should have gained by saying it once. Then, what is the relation between the value of merit and of time? And what value shall I give to my time? It is worth more in the morning when I am fresh; less after dinner; it has probably a middle value in the evening up to, say, six o’clock, when it rapidly increases till bed-time. But how measure all this quantitatively for the purposes of the formula?

Then there is the difficulty of assessing the probabilities. Dr. McDonald takes it for granted that a probabilist will assess them differently from an equiprobabilist. Here, then, we are landed in all the dangers of subjectivism. In short, Dr. McDonald’s great principle had better be confined to the class of cases for which it is suitable, and for which it is commonly employed by theologians. If we attempt to apply it to other cases, we shall find that it is no fixed guide, but a very weathercock which will point in any direction towards which the impulse of passion drives us. The foregoing strictures on the special conclusions arrived at by Dr. McDonald in his book suggest a question with regard to his fundamental assumption, that the general principles as stated in our text-books on Human Acts, etc., are not in keeping with the particular conclusions formulated in the treatises on the special virtues. Is this true?

It seems to me that it is only true in a very qualified and immaterial sense. The general principles necessarily abstract from special features and particular circumstances, which have to be considered and allowed for, when the general principles are applied to concrete cases. This is no more than has to be done in other sciences. When we apply the truths of pure mathematics to physical science, corrections and allowances have to be made continually. The infinite complications of nature are too complex for our abstract theories. In some such sense it may be said that the intricacies of human acts cannot be expressed in a simple formula. And yet, just as no one would deny the truth and the value of pure mechanics, because the truths it teaches have to be applied with caution and with necessary corrections when we come to applied mechanics, so the truth and the value of the general principles of morality should not be impugned because in their application we have to allow for special circumstances. This is done by theologians, who frequently apply a general principle tacitly, without quoting it in so many words, just as the mathematician uses the multiplication table, or the logician the principle of contradiction. If Dr. McDonald will give due attention to these considerations, I shall be surprised if the inconsistency which he has noticed in our text-books will not disappear.