Why did the Church modify canon law in 1983 to permit marriages between second cousins, whereas before 1917 and since 1215 it had prohibited even third cousins from marrying? Prior to 1215, the use of a far more stringent counting method had raised the prohibited degrees of affinity higher still.
I personally feel that the stricter pre-1983 rulings were superior given all we now know about genetics, so I’m curious to understand why the ecclesiastical rules have been progressively relaxed since 1917. I’m aware that many people, especially the nobility and royalty, received dispensations owing to the virtual impossibility of avoiding blood relation within their exceedingly small pool of potential partners.
The Eastern Orthodox Church continues to prohibit second cousins from marrying, so far as I have been able to discern.
First and second cousin marriages were initially banned at the Council of Agde in AD 506 and the latter, as stated at the beginning of my post, has only been permitted since 1983.
First we must recognize there is two books of Canon law.
One belongs to the Latin rite and the other to the eastern rite (byzantine, maronites, chaldean, syriac, syrio-Malabar, Ukrainian, ruthuanian among others.)
In the Latin rite
From the book My Catholic Faith by Most reverend Louis LaRavoire Morrow, S.T.D. Bishop of Krishnagar page 346- and part of pg. 347 says
"167. Impediments to matrimony
What are Impediments to matrimony?
Impediments to matrimony are obstacles to the validity or lawful ess of a marriage.
- Impediments to matrimony are certain restrictions imposed by the law of God or of the Church which render a marriage contract invalid or unlawful if such restrictions are violated when entering into the marriage. In safeguarding the Sacrament of Matrimony, the church declares that certain circumstances tend to lessen or actually destroy the sacred nature of the Sacrament. Such obstacles are called “Impediments” , since they obstruct sacramental sanctity.
Whenever circumstances incompatible with the Sacrament or contract of Matrimony exist, the Church has established Impediments; other reasons, such as the general welfare of society or the protrection of the matrimonial bond may have caused the placing of impediments.
- When Impediments exist, the Church either completely forbids the administration of the Sacrament, or requires special assurance that the dangers may be reduced as far as possible; in this latter case, a matrimonial “dispensation” is granted.
- There are two kinds of impediments:
(a) Detriment (also called a nuking or nullifying) impediments render an attempted marriage altogether null and void, invalid. Dispensation are only rarely granted for deriment impediments. Should an attempt at marriage be made without dispensation, there is no marriage.
Such an invalid marriage must be either dissolved, or the impediment removed by a dispensation, and the marriage performed validly. If a marriage is dissolved, the contracting parties are free to marry other partners, if they so wish.
(b) Prohibitive (also called impediment or hindering) impediments render a marriage unlawful, illicit, but valid. In this case, the couple are married, though unlawfully. The marriage cannot be disolved.
Prohibitive impediments are easily dispensed. but good Catholics should prefer to comply with the wishes of the Church, which put these impediments for the good of its members."
I am not going to list all the impediments I am going to mention only in relationship to this topic according to the Latin rite
"Which are chief deriment impediments? - the chief deriment impediments are:
…
4. Blood relationship or consanguinity.
The Church forbids the Marriage of close relatives, in order to enforce the respect due to blood relations, and to increase the number of families bound together in friendship, thus promoting union among men. The prohibition also aims to prevent the birth of physically and mentally defective children, often found resulting from such marriages.
- Close affinity. This means relationship by marriage. The survivor cannot marry the blood relations of his dead spouse.
In the direct line, as a step daughter or mother-in-law, no dispensation is granted. In the collateral line the impediment extends to the second degree, and may be dispensed.
…
- Spiritual affinity. Without dispensation, sponsors in Baptism cannot marry their godchildren.
A lay person cannot marry the person to whom he administered lay baptism.
- Legal relationship. Those who by civil law are incapable of contracting a marriage by reason of legal relation arising from adoption are incapable, by Church law, of a valid marriage
The impediment partakes of natural of the Civil impediment which conditions it: it is prohibitive, where the civil impediment is prohibitive, and deriment or annulling, where the civil impediment is diriment."
But do not forget this is with regard to the Latin rite.
The eastern has their Canon laws (which are very similar, yet they have small differences) I still I cannot speak for them(eastern rite). In order for you to find more information you will need to speak to your Parish priest he will explain you the disciplines of both and historical backgrounds. Although both are of the same Church they have different disciplines in regards to some matters ( I do not know the specifics in regards to what)
But I do know that a Catholic priest can explain in further detail.
You can also ask a priest from their rite and they can also explain.
It is not that one is better than another.(since we both are the same church) however both eastern and Latin rite has different disciplines and cultural traditions. Regardless the mass and worship is the same, we have the same beliefs, same sacraments.