Whether seven years is fittingly assigned as the age for betrothal?

Objections

Objection 1 : It would seem that seven years is not fittingly assigned as the age for betrothal. For a contract that can be formed by others does not require discretion in those whom it concerns. Now a betrothal can be arranged by the parents without the knowledge of either of the persons betrothed. Therefore a betrothal can be arranged before the age of seven years as well as after.
Objection 2 : Further, just as some use of reason is necessary for the contract of betrothal, so is there for the consent to mortal sin. Now, as Gregory says (Dial. iv), a boy of five years of age was carried off by the devil on account of the sin of blasphemy. Therefore a betrothal can take place before the age of seven years.
Objection 3 : Further, a betrothal is directed to marriage. But for marriage the same age is not assigned to boy and girl.
Objection 4 : Further, one can become betrothed as soon as future marriage can be agreeable to one. Now signs of this agreeableness are often apparent in boys before the age of seven. Therefore they can become betrothed before that age.
Objection 5 : Further, if persons become betrothed before they are seven years old, and subsequently after the age of seven and before the age of maturity renew their promise in words expressive of the present, they are reckoned to be betrothed. Now this is not by virtue of the second contract, since they intend to contract not betrothal but marriage. Therefore it is by the virtue of the first; and thus espousals can be contracted before the age of seven.
Objection 6 : Further, when a thing is done by many persons in common, if one fails he is supplied by another, as in the case of those who row a boat. Now the contract of betrothal is an action common to the contracting parties. Therefore if one be of mature age, he can contract a betrothal with a girl who is not seven years old, since the lack of age in one is more than counterbalanced in the other.
Objection 7 : Further, those who at about the age of puberty, but before it, enter into the marriage contract by words expressive of the present are reputed to be married. Therefore in like manner if they contract marriage by words expressive of the future, before yet close on the age of puberty, they are to be reputed as betrothed.