Whether consanguinity is an impediment to marriage by virtue of the natural law?
Objections
❌ Objection 1 : It would seem that consanguinity is not by natural law an impediment to marriage. For no woman can be more akin to a man than Eve was to Adam, since of her did he say (Gn. 2:23): "This now is bone of my bones and flesh of my flesh." Yet Eve was joined in marriage to Adam. Therefore as regards the natural law no consanguinity is an impediment to marriage.
❌ Objection 2 : Further, the natural law is the same for all. Now among the uncivilized nations no person is debarred from marriage by reason of consanguinity. Therefore, as regards the law of nature, consanguinity is no impediment to marriage.
❌ Objection 3 : Further, the natural law is what "nature has taught all animals," as stated at the beginning of the Digests (i, ff. De just. et jure). Now brute animals copulate even with their mother. Therefore it is not of natural law that certain persons are debarred from marriage on account of consanguinity.
❌ Objection 4 : Further, nothing that is not contrary to one of the goods of matrimony is an impediment to marriage. But consanguinity is not contrary to any of the goods of marriage. Therefore it is not an impediment thereto.
❌ Objection 5 : Further, things which are more akin and more similar to one another are better and more firmly united together. Now matrimony is a kind of union. Since then consanguinity is a kind of kinship, it does not hinder marriage but rather strengthens the union.