Article XII. Error, Slavery, Imbecility

By error is understood a mistaken judgement by which one person or thing is taken for another. It differs from ignorance, which is merely the absence of knowledge. Error, if it is substantial, annuls marriage as it does other contracts, by the law of nature itself. For a contract is not valid unless there be an agreement of wills between the contracting parties, and there cannot be that agreement if one of the parties is in error about the substance of the contract. There will be such a substantial error when there is a mistake about the person with whom marriage is contracted. If A thinks he is marrying B and intends to marry B, the marriage will be invalid if the other party to the contract is C, not B. Sometimes a mistake about the quality or rank of the other party may be substantial and invalidate the marriage. Thus, if a woman thinks she is marrying the eldest son of a peer, and only intends to marry the eldest son, who she thinks is present, the marriage will be null and void if the bridegroom is not the eldest son of a peer. Ordinarily, however, a mistake about the quality or condition of the other party will not be substantial, and will not invalidate the contract. If the lady intends to marry the person present who she wrongly thinks is the eldest son, the marriage will be valid. It is possible that there should be a substantial mistake about the subject-matter of the contract of marriage. Thus, if a woman thinks that marriage is a mere union of friendship between the parties, and when she marries does not intend to give her husband any right to have children by her, the marriage is invalid. Mere ignorance as to the way in which children are brought into the world does not invalidate marriage (Can. 1083, 1082).

If a freeman married a slave under the mistaken belief that she was free, the marriage was null and void by ecclesiastical law; if he married knowing the servile condition of the other party, the marriage was valid. To this extent the Church received the Roman legislation on the marriage of slaves, according to which they could not validly marry one that was free, and their marriages among themselves were merely at the good will of their masters. The law of the Church corrected what was inhuman in the Roman civil law, and adopted its provisions as far as they were in harmony with Christian principles. Nowadays, of course, this impediment can scarcely be of practical importance in any part of the world (Can. 1083, sec. 2, 1);

Imbeciles who have not the use of reason are incapable by the law of nature of contracting a valid marriage, unless it is contracted in a lucid interval. If the loss of reason supervenes on marriage which has been validly contracted already, it cannot of course annul the marriage.