Rule XXVI. We must distinguish between a natural incapacity of vowing or swearing at all, and an incapacity of doing it lawfully; and between a true nullity, and when the oath is only quasi nullum, or as null quoad effectum, or such as I must not keep. There are many real oaths and vows which must not be kept, and so far are quasi nulla as to the effecting of the thing vowed; but they are not simply null; for they have the effect of making the man a sinner and perjured. They are sinful vows, and therefore vows. A natural incapacity proveth it no vow at all; but if I am naturally capable, and only forbidden, (by God or man,) this maketh it not no vow, but a sinful vow, of which some must be kept and some must not.
Cases in which a vow must not be kept.
In these following cases a real vow is quasi nullum, or must not be kept.
1. In case the thing vowed (all things considered) be a thing which God hath forbidden to be done; that is, in case it be a thing in itself evil; but if the thing in itself be a duty, though there be some inseparable sins which we shall be guilty of in the performance, we must not therefore leave the duty itself undone which we have vowed: as if I vow to praise God, and yet am sure that I cannot praise him without a sinful defect of that love and delight in him which is due, I must not therefore forbear to praise him; else we must cast off all other duty, because we cannot do it without some sin. But yet, though in case of unwilling infirmity, we must thus do the duty though we are sure to sin in it, yet in case of any chosen, voluntary sin, which we have an immediate power to avoid, we must rather forbear the duty itself (vowed or not vowed) than commit such a sin; as if I vow to preach the gospel, and am forcibly hindered unless I would voluntarily tell one lie, or commit one sin wilfully for this liberty; I ought rather never to preach the gospel; nor is it then a duty, but become morally impossible to me; as if in France or Spain I may not preach unless I would take Pope Pius's Trent confession or oath. Nay, if those very defects of love, and wandering thoughts, which now inseparably cleave to my best performances, were morally and immediately in my power, and I could avoid them, I ought not electively and by consent to commit them, for any liberty of duty, but rather to forbear the duty itself as no duty to me when it cometh upon such conditions; for then it is supposed that I could serve God better without that duty, because I could love him more, &c.
Yet here is observable a great deal of difference between omissions and commissions. A man may never commit a sin that good may come by it, though he vowed the good; but a man may ofttimes omit that which else would have been his duty, to do some good which he hath vowed; for negative commands bind semper et ad semper; but the affirmative do not (at least as to outward duty); therefore in case of necessity a man may himself consent to the present omission of some good, for the escaping of greater, unavoidable omissions another time, or for the performing of a vow or greater duty which is to be preferred.
2. A vow is not to be kept, when the matter of it is unjust and injurious to another (unless you have his consent): as if you vow to give away another man's lands or goods, or to do him wrong by word or deed; or if you vow to forbear to pay him his due, or to do that which you owe him: as if a servant vow to forbear his master's work (unless it be so small an injury as he can otherwise repair); or a husband, or wife, or parents, or children, or prince, or subjects should vow to deny their necessary duties to each other. Here man's right together with God's law doth make it unjust to perform such vows.
3. A vow is as null or not to be kept, when the matter is something that is morally or civilly out of our power to do: as if a servant, or a child, or subject vow to do a thing, which he cannot do lawfully without the consent of his superior: this vow is not simply null, for it is a sinful vow (unless it was conditional). Every rational creature is so far sui juris, as that his soul being immediately subject to God, he is capable of obliging himself to God; and so his vow is a real sinful vow, when he is not so far sui juris as to be capable of a lawful vowing, or doing the thing which he voweth. Such a one is bound to endeavour to get his superior's consent, but not without it to perform his vow; no, though the thing in itself be lawful. For God having antecedently bound me to obey my superiors in all lawful things, I cannot disoblige myself by my own vows.
Yet here are very great difficulties in this case, which causeth difference among the learnedest, pious casuists. 1. If a governor have beforehand made a law for that which I vow against, it is supposed by many that my vow is not to be kept, (the thing being not against the law of God,) because the first obligation holdeth. 2. Yet some think that magistrates' penal laws binding but aut ad obedientiam aut ad pœnam, to obedience or punishment, I am therefore obliged in indifferent things to bear his penalty, and to keep my vow.76 3. But if I first make an absolute vow in a thing indifferent, (as to drink no wine, or to wear no silks, &c.) and the magistrate afterwards command it me, some think I am bound to keep my vow; because though I must obey the magistrate in all things lawful, yet my vow hath made this particular thing to be to me unlawful, before the magistrate made it a duty. 4. Though others think that even in this case the general obligation to obey my superiors preventeth my obliging myself to any particular which they may forbid in case I had not vowed it, or against any particular which they may command. 5. Others distinguish of things lawful or indifferent, and say that some of them are such as become accidentally so useful or needful to the common good, the end of government, that it is fit the magistrate make a law for it, and the breaking of that law will be so hurtful, that my vow cannot bind me to it, as being now no indifferent thing; but other indifferent things they say belong not to the magistrate to determine of (as what I shall eat or drink, whether I shall marry or not, what trade I shall be of, how each artificer, tradesman, or professor of arts and sciences shall do the business of his profession, &c.) And here the magistrate they think cannot bind them against their vows, because their power of themselves in such private cases is greater than his power over them in those cases. All these I leave as so many questions unfit for me to resolve in the midst of the contentions of the learned. The great reasons that move on both sides you may easily discern. 1. Those that think an oath in lawful things, obligeth not contrary to the magistrate's antecedent or subsequent command, are moved by this reason, That else subjects and children might by their vows exempt themselves from obedience, and null God's command of obeying our superiors. 2. Those that think a vow is obligatory against a magistrate's command, are moved by this reason, Because else, say they, a magistrate may at his pleasure dispense with all vows, except in things commanded before by God: for he may come after and cross our vows by his commands, which, against the pope's pretensions, protestants have denied to be in the power of any mortal man. And God, say they, hath the first right, which none can take away. I must not