Late Medieval Canon Law on Marriage 
Image: The Arnolfini Marriage (1434), by Jan van Eyck (c. 1395-c. 1441). Image source: WebMuseum of Art

The foundations of church law on marriage were laid during the eleventh and twelfth centuries, the period of the Gregorian Reforms. These can be summarized briefly:

  • With regard to marriage and divorce, the legislation of the eleventh and twelfth centuries implanted firmly the doctrine of marital indissolubility; the only permissible grounds for divorce and remarriage were impotence, incest (i.e., marriage within the forbidden degrees of consanguinity and affinity), and adultery. This threatened to end the widespread practice of divorce; it also encouraged the church to assert its judicial authority over marriage law; and it diminished the ability of family and kin to control marriage independently.
  • With respect to incest, the forbidden degrees of consanguinity and affinity remained high. In 1059, Pope Nicholas II issued an encyclical which required that "if anyone had taken a spouse within the seventh degree, he will be forced canonically by his bishop to send her away; if he refuses, he will be excommunicated." In 1215, the Fourth Lateran Council reduced the number of prohibited degrees from seven to four. Still, the cummulative effect was to encourage exogamy--i.e., marriage outside one's native community--and the growth of regional marriage markets.
  • The reforms codified a trend toward monogamy, already well under way by the turn of the millenium, which supplanted earlier forms of polygynous marriage and concubinage, such as Friedelehen (a kind of second-class marriage).
  • The canonists also asserted authority over the sexual practices of laypeople: the reform-era legislation was generally milder than earlier regulations, but continued to uphold the notion that sex for any purpose other than procreation within marriage was sinful. All nonmarital sex was condemned as criminal; all homosexual intercourse was forbidden.
  • Finally, the reform legislation reinforced and implemented long-standing prohibitions against clerical marriage and concubinage.

It is unclear how consistently the provisions on forbidden degrees of incest were enforced; considerable controversy centered on the reckoning of degrees of kinship, for which there were two systems in operation, the Roman and the far stricter Germanic scheme. Under the Roman scheme, degrees of kinship were calculated by counting the number of acts of generation separating ego and other. Siblings, under this system, were separated by two degrees of kinship, one for the act of generation between the first sibling from her parents, another for the act of generation between the parents and the second child. Similarly, an uncle and niece are separated in the third degree.

Image right: the "Germanic" system for calculating degrees of separation, adapted from Isidore of Seville (Etymologarium sive Originum, ed. W.M. Lindsay, Oxford, 1911); in Jack Goody, The Development of the Family and Marriage in Europe (Cambridge: Cambridge University Press, 1983), 143.

According to the Germanic calculation, degrees of kinship were based on the unity of the sibling group, all of whom were related in the first degree, so that all brothers and sisters of a single marital couple were related to each other in the first degree. By this system of reckoning from a hypothetical "ego" (ipse on the chart), seven degrees of separation included all descendents from a pair of common great-great-great-great-great-grandparents. Under this system, the circle of kinship embraced all descendants of a common great-grandfather, i.e., second-cousins.

Moreover, these provisions left open the question of how a marriage came into being. This matter was given much sharper definition in Gratian's Decretum (ca. 1140). Gratian tended to regard marriage as a process with two stages: (a) in initiation, the couple exchanged freely-consenting vows of marriage, which created a spiritual union between them; in the (b) completion or perfection of the marriage, the couple created a physical union by consummating their bond sexually. Both stages were necessary to complete a marriage: no sexual union constituted marriage without consent to marry, just as no marriage as wholly formed without sexual union. Indeed, for Gratian it was sexual intercourse that transformed the union into a "sacrament" and made a marriage indissoluable. If marriage was situated between three kinds of union -- sexual, spiritual, and social -- Gratian's Decretum shifted definitions strongly toward the first of these. But not to the neglect of consent: only a marriage freely entered was valid, if both parties were at least seven years old, both were Christian, and neither were bound by an oath of chastity.


With its emphases on the necessity of consent and on sex as a positive good, the High Medieval conceptualization of marriage represented a departure from the hostility and revulsion toward sexuality that characterized the writings of many earlier canonists. As it developed after Gratian, canon law also distinguished between two kinds of vows, and weighed them differently depending on whether these vows had been consummated sexually.

1. “Present Vows” (sponsalia per verba de praesenti)
Present vows were an exchange of promises in the present, for the present, between consenting male and female (i.e., "I, Margot, take you, Hannes, to be my husband now and forever"). In general, these were thought to constitute a valid marriage, even if the vows were exchanged in secret and without the consent of parents and kin.

2. “Future Vows” (sponsalia per verba de futuro)
Slightly more complicated were future vows of marriage exchanged between consenting parties (i.e., "I, Margot, promise to take you, Hannes, to be my husband at such-and-such a date"). Future vows were obligating, but did not constitute an indissoluable marriage for the present. Therefore future vows could be dissolved
In this system, the social dimension of marriage got short shrift: Gratian was no enthusiast for clandestine marriage, but his emphasis on consent and sexual consummation left little room for parental consent or the need for public, ceremonial marriage. Indeed, the emphasis on consent in marriage only grew stronger: Pope Alexander III (1159-1181) ruled that future vows, if they were given freely and consummated sexually, constituted an indissoluable marriage. Neither parental or kin-group consent, nor dowries, nor publicity were needed to complete a marital union.

At the same time, however, canon law also insisted that marriages should be public and that parents should have a say in their creation. In addition to banning marriage within the fourth degree of consanguinity, the Fourth Lateran Council had also banned marriages concluded in secrecy. The Council's intent had been to provide an effective means of enforcing consanguinity laws: by making marriage public, incest impediments might come to light more readily. The Council also intended to counteract a series of  problems that had arisen from a definition of marriage based on consent and sex. In a court of law, for example, it was difficult to prove or disprove whether the parties to a marriage had exchanged vows consensually or had consummated the union freely. Public marriage had placing the consent of both parties on display and reinforcing it with the testimony of witnesses. Also, secret marriages had the potential to invalidate subsequent, public marriages and this, in turn, threatened the social functions of marriage as a tool of alliance-making and property transfer. As James A. Brundage notes,

The upper classes sought to make their marriages as public and as splendid as possible, not only as a matter of honor and social obligation, but also to assure that property transactions connected with the marriage would be honored.
From 1215 on, therefore, canon law on marriage formed between the sometimes contradictory requirements of consent and publicity, which may explain the hesitance of theologians to affirm the sacramentality of marriage unequivocally. Albert the Great (c. 1200-1280) allowed it, but only because the sacrament helped married people achieve the goals of marriage (Brundage, 432). Duns Scotus (1270-1308) solved the problem by distinguishing two types of marriage: by itself, free mutual consent created a valid marriage, but only a public, church ceremony could establish a sacramental marriage. Others absorbed sacramentality into Gratian's two stages of marriage, initiation and completion. According to this view, a couple received one portion of the sacramental grace that marriage conferred in the first stage, when they exchanged vows; they received the second portion, so to speak, when they consummated the union sexually. The view which ultimately prevailed, however, was that of Thomas Aquinas, who affirmed that marriage was a sacrament and that the exchange of consent itself conferred grace (Brundage, 433). 
In 1215, the Fourth Lateran Council made the following rulings on incest and clandestine marriage:

§50. On the Restriction of Prohibitions to Matrimony
It should not be judged reprehensible if human decrees are sometimes changed according to changing circumstances, especially when urgent necessity or evident advantage demands it, since God himself changed in the new Testament some of the things which he had commanded in the old Testament. Since the prohibitions against contracting marriage in the second and third degree of affinity, and against uniting the offspring of a second marriage with the kindred of the first husband, often lead to difficulty and sometimes endanger souls, we therefore, in order that when the prohibition ceases the effect may also cease, revoke with the approval of this sacred council the constitutions published on this subject and we decree, by this present constitution, that henceforth contracting parties connected in these ways may freely be joined together. Moreover the prohibition against marriage shall not in future go beyond the fourth degree of consanguinity and of affinity, since the prohibition cannot now generally be observed to further degrees without grave harm. The number four agrees well with the prohibition concerning bodily union about which the Apostle says, that the husband does not rule over his body, but the wife does; and the wife does not rule over her body, but the husband does; for there are four humors in the body, which is composed of the four elements. Although the prohibition of marriage is now restricted to the fourth degree, we wish the prohibition to be perpetual, notwithstanding earlier decrees on this subject issued either by others or by us. If any persons dare to marry contrary to this prohibition, they shall not be protected by length of years, since the passage of time does not diminish sin but increases it, and the longer that faults hold the unfortunate soul in bondage the graver they are.

§51. Prohibition of Clandestine Marriages
Since the prohibition against marriage in the three remotest degrees has been revoked, we wish it to be strictly observed in the other degrees. Following in the footsteps of our predecessors, we altogether forbid clandestine marriages and we forbid any priest to presume to be present at such a marriage. Extending the special custom of certain regions to other regions generally, we decree that when marriages are to be contracted they shall be publicly announced in the churches by priests, with a suitable time being fixed beforehand within which whoever wishes and is able to may adduce a lawful impediment. The priests themselves shall also investigate whether there is any impediment. When there appears a credible reason why the marriage should not be contracted, the contract shall be expressly forbidden until there has been established from clear documents what ought to be done in the matter. If any persons presume to enter into clandestine marriages of this kind, or forbidden marriages within a prohibited degree, even if done in ignorance, the offspring of the union shall be deemed illegitimate and shall have no help from their parents' ignorance, since the parents in contracting the marriage could be considered as not devoid of knowledge, or even as affecters of ignorance. Likewise the offspring shall be deemed illegitimate if both parents know of a legitimate impediment and yet dare to contract a marriage in the presence of the church, contrary to every prohibition. Moreover the parish priest who refuses to forbid such unions, or even any member of the regular clergy who dares to attend them, shall be suspended from office for three years and shall be punished even more severely if the nature of the fault requires it. Those who presume to be united in this way, even if it is within a permitted degree, are to be given a suitable penance. Anybody who maliciously proposes an impediment, to prevent a legitimate marriage, will not escape the church's vengeance. (emphasis added)


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