The term probable means provable, not guessed at, or jumped at without reason. There must be sound reason {17} adduced to constitute probability. The doubt must be founded on a positive opinion against the existence, interpretation, or application of the law. It must be more than mere negative doubt, more than ignorance, more than vague suspicion, especially must it be more than a sentimental impression. There is a mental condition, which easily passes over into disease, wherein a man habitually can not make up his mind. This flabbiness has nothing to do with Probabilism. The opinion against a law to constitute Probabilism must be solid. It must rest upon an intrinsic reason from the nature of the case, or an extrinsic reason from authority,--always supposing the authority cited is really an authority. Many men sitting upon the supreme bench in the Court of Science and called authorities by friends and newspapers, are only fools in good company. The probability must also be comparative. What seems to be a very good reason when standing alone may be very weak when compared with a reason on the other side. When we have weighed the arguments on both sides, and we still have good reason left for standing by our opinion, our opinion is probable. The probability is, moreover, to be practical. It must have considered all the circumstances of the case. The principles presented here have been arranged, as we said, with a view toward application in judging the morality of actions that may occur in cases of ectopic gestation, and we shall apply the doctrine of probabilism in the question, does the commandment "Thou shalt not kill" bind in certain cases of ectopic pregnancy? It is also necessary to add the principles underlying our duty to preserve human life. 1. It is never lawful directly or indirectly to kill an innocent man. "Insontem et justum non occides" (Exod. xxiii. 7). An _innocent_ man is one that has not by any human act done harm to another man or to society commensurate with the loss of his life. _Directly_ means to kill either as an end, say, for revenge, or as a means toward an end. A man is a person, an intelligent being, therefore free, and autocentric; he belongs to no one except to God, who made {18} him; he is by that very fact distinguished from brutes or things which may belong to another. Now, if you kill a man, you destroy his human nature by separating his soul and body, you subordinate and sacrifice him wholly to yourself, make him entirely yours, which is unjust. Even the state has no right to kill an innocent man. A foetus in the womb, only a few hours old, is as much a human being as a man fifty years of age, and this natural law holds for the foetus as for the man.