본 논문에서는 조선 전기 收養·侍養의 실태와 立後法 정착 과정을 검토함으로써 조선 전기의 사회상과 유교적 가족질서의 정착 과정에 대해 살펴보았다.
고려시대에는 夫妻 양측의 친족 뿐 아니라 夫妻에 모두 혈연관계가 없는 他人의 입양이 모두 가능하였다. 그리고 가계계승이 아닌 다른 목적을 가지고 입양을 선택하는 경우가 많았던 것 같다. 이러한 고려의 입양 관행은 조선 건국 후에도 지속되었다. 그런데 유교적 가족질서를 확립하고자 하였던 조선의 위정자들은 아들이 없는 사람이 가계계승을 위해 夫側 동성 친족을 양자로 세우는 것을 가장 이상적인 입양 형태로 생각하였다. 이에 따라 기존의 입양 관행을 규제하는 법을 제정하였다. 이는 ‘수양’과 ‘시양’을 명확히 구분하여 시양자녀의 법제적 위상을 약화시키는 방향으로 이루어졌다. 즉, 侍養子女에 대한 상속분을 제한하였으며, 收養父母에 대한 3년상을 법제화하면서도 侍養父母의 服喪 규정은 제정하지 않았다. 이렇게 조선의 위정자들은 유교적 제사형태 정착에 장애가 되는 입양 관행을 금지하는 강제적 조치를 취하지 않고 입양시의 나이로 수양과 시양을 구분하여 시양자녀의 위상을 약화시키는 간접적인 규제 방법을 선택하였다. 이러한 국초의 수양, 시양 관련 법규 제정은 입후법 제정의 전단계의 정책이라 할 수 있다. 이러한 상황에서 15세기에 수양·시양자녀 입양은 성행할 수 있었다.
15세기 수양·시양자녀 입양 대상을 살펴보면, 夫妻 양측의 친족 입양과 夫妻에 모두 혈연관계가 없는 他人의 입양이 모두 가능하였다. 이 중 먼저 夫妻 양측 친족의 입양 사례를 살펴보면, 夫妻가 각각 자신과 혈연관계가 있는 친족을 계통을 따지지 않고 입양하였음을 확인할 수 있다. 이러한 현상이 나타났던 이유는 다음 두 가지로 정리될 수 있다. 첫째 계통의 구분 없이 혈연이 중시되던 고려시대 친족조직의 특성이 이어지고 있었기 때문이었다. 둘째 자신에게 재산을 준 조상의 孫外에 재산을 증여·상속하지 않으려는 관행이 있었기 때문이었다. 이 때문에 관행적으로나 법적으로 재산 증여·상속의 대상자가 되는 수양·시양자녀를 입양할 때 夫妻가 각각 자신과 혈연관계가 있는 친족 중에서도 가까운 친족을 입양하려고 하는 현상이 나타났다. 다음으로 夫妻에 모두 혈연관계가 없는 他人 입양 사례를 살펴보면, 자신의 이익을 극대화하기 위해, 혹은 현실적인 필요에 의해, 혹은 친밀감으로 인하여 입양 대상에 제한을 받지 않고 자유롭게 양부모, 양자녀 관계를 맺었음을 확인할 수 있다.
이 시기 수양·시양자녀 입양 목적을 살펴보면, 매우 다양한 목적의 입양이 이루어졌음을 확인할 수 있다. 상류층을 중심으로 수양·시양자녀의 입양의 주요한 목적을 살펴보면 다음과 같다. 첫째 어린아이의 양육을 위해, 혹은 생시에 양자녀로부터 효도를 받고 사후에 喪事나 제사를 담당해주기를 기대하면서 입양을 하였다. 둘째 왕실에서는 왕실 여성들과 現王의 왕자, 왕손이 양모, 양자의 관계를 맺음으로써 왕실의 화합과 안정을 도모하기도 하였고, 民家에서는 妾과 嫡族 사이에 양모, 양자녀 관계를 맺음으로써 嫡族과 첩 사이의 원만한 관계 형성을 꾀하기도 하였다. 셋째 王子女나 권세가 자손이 다른 사람의 양자녀가 됨으로써 왕자녀나 권세가 측에서는 재산을 증여·상속받고 양부모 측에서는 출세, 이권을 얻는 정략적 입양이 행해지기도 하였다.
이렇게 15세기에 입양 대상과 목적에 크게 제한을 받지 않는 입양이 성행할 수 있었던 이유로는 다음 네 가지를 들 수 있다. 첫째 수양과 시양을 구분하는 기준 외에 수양자녀와 시양자녀의 자격 기준이 법으로 규정되지 않았다. 둘째 양부모와 수양·시양자녀의 관계는 그 안정성이 법적으로 보장되어 있지 않았다. 셋째 수양과 시양은 양부모와의 관계보다는 친부모와의 관계가 우선시되었다. 넷째 신분이 다른 사람끼리 양부모, 양자녀 관계가 형성되더라도 수양자녀나 시양자녀의 신분에 양부모의 신분이 영향을 미치지 않았다. 이러한 이유로 이 시기 수양, 시양은 비교적 자유롭고 쉽게 성립될 수 있었다.
수양·시양자녀 입양이 성행하고 있는 상황에서 세종 19년에 立後法이 제정되었다. 본격적으로 아들 없는 집안의 유교적 제사형태 확립을 위한 법규가 제정되었던 것이다. 입후법의 제정은 가계계승을 위한 夫側 同姓 친족의 입양이 거의 이루어지지 않고 있는 상황에서 가계계승을 원하는 사람을 위하여 立後의 기준을 마련하였다는데 그 의미가 있다. 입후법 제정 당시에는 夫側 동성 친족 중 支子와 族孫를 입후 대상자로 규정하고 형제와 尊屬의 입후는 금하였으며, 『경국대전』 최종본인 乙巳大典에서는 손자 항렬의 입후를 금함으로써 夫側 동성 친족 중 支子로 昭穆에 합당한 사람만이 입후대상자가 될 수 있도록 규정하였다. 또한 개별 입후에 대해 허가제를 실시하여 중앙 정부에서 감독함으로써 입후를 하고자 하는 개인들이 입후법을 철저하게 준수하도록 하였다. 이에 따라 입후를 하고자 하는 사람은 예조에 所志를 제출하여 繼後立案을 발급받아야 했다. 그런데 입후법은 입후를 강제하는 법이 아니라 입후의 기준을 제시한 법이었다. 따라서 정부에서는 입후법 정착을 위해 繼後子의 嫡子承重子로서의 지위를 보장하는 법을 제정하였다.
이 외에도 입후법 정착을 위한 다음과 같은 조치들이 행해졌다. 입후법을 제정한 직후 세종은 왕명으로 후사없이 사망한 議親과 功臣의 계후자를 세워줌으로써 입후법 제정을 알렸다. 그리고 중종반정 이후에는 입후법에 어긋나는 입후라고 하더라도 왕의 特命으로 입후를 허락하는 法外立後가 나타나게 되었다. 법외입후는 연산조에 被禍된 사람들의 후사를 이어준다는 명목으로 시작되었지만 점차적으로 왕의 일시적인 은혜라는 측면에서 벗어나 입후를 장려하는 수단으로 이용되기도 하였다.
입후법 제정 직후에는 아들이 없더라도 입후를 하는 사람이 소수였지만 유교적 제사형태가 정착되어가면서 입후를 하는 사람들은 점점 증가해갔다. 입후법이 제정된 이후에도 15세기에 입후를 하는 사람이 소수였던 이유는 앞에서도 언급한 바 있던 당시의 친족관계와 상속관행에 기인한 바 크다. 특히 孫外與他 금지 관행은 입후 증가의 실질적인 장애요소가 되었다. 이 관행 때문에 처측에서는 夫妻의 재산을 모두 夫의 친족인 계후자에게 상속하는 것을 받아들이기가 어려웠던 것이다. 그러나 유교적 제사형태가 확립되어 가고 개인의 안정적 봉사자 확보에 대한 욕구가 강화되어 가면서 계후자의 필요성이 커지기 시작하였다.
이러한 변화의 조짐은 수양·시양자녀 입양 형태의 변화를 통해 확인할 수 있다. 16세기 分財記에는 夫의 친족을 收養子나 侍養子로 삼아 처의 재산까지 증여한 사례들이 나타나며, 이 중에는 처의 재산을 모두 증여한 사례도 있다. 그리고 이 경우 夫의 친족을 입양한 목적은 이들에게 奉祀를 맡기고자 하거나 가계계승자로서의 역할을 기대해서였다. 안정적 봉사자 확보의 욕구가 강화됨으로써 종래의 孫外與他 금지 관행이 약화되는 현상이 나타나게 되었던 것이다. 이는 당시에 사회적으로 입후에 대한 거부감이 감소되어가고 있었음을 의미하는 것이라 할 수 있다. 이에 따라 남편이 사망한 이후에도 적극적으로 계후자를 세우고자 하는 여성들이 나타났고, 수양자나 시양자를 계후자로 삼고자 하는 사람들도 나타나게 되었다.
또한 母系의 신분이 천한 첩자에게 가계계승을 시키고자 하지 않았던 경향도 입후 증가에 영향을 미쳤다. 16세기에 嫡妻와 妾에 모두 아들이 없는 경우에만 입후를 할 수 있도록 한 『경국대전』 입후조 규정의 적용이 완화되는 상황에서 嫡子가 없고 妾子만 있는 사람이 첩자 봉사를 피할 가장 확실한 방법은 법적으로 보장된 안정적 가계계승자인 계후자를 세우는 일이었던 것이다.
이를 통해 보건대 입후의 증가는 19세기에 이르기까지 지속적으로 나타나지만 그 단초는 16세기에 이미 마련된 것이라 할 수 있을 것이다. 또한 이와 같은 입후 증가의 과정은 바로 아들 없는 집안에서의 父系중심 가족질서의 강화의 모습을 보여주는 것이기도 하다.

In this article, the practice of Suyang adoption(收養) and Shiyang adoption(侍養) which prevailed during the early half period of the Joseon dynasty, and the establishment of 'the Heir-naming law'(立後法), will both be examined, in order to ascertain the societal nature of the Joseon dynasty in this period, and to evaluate the process in which Confucian-based family order was established.
During the Goryeo dynasty period, not only relatives of the husband or wife, but also persons who were not related to any of the married couple, were all allowed to be adopted. Yet there were many more cases in which adoption was chosen for certain purposes other than naming a person who would preserved the family line. Such practices of adoption from the Goryeo dynasty days continued to exist even after the Joseon dynasty was founded. Yet the leaders inside the Joseon government intended to establish a Confucian-based family order, and considered the case in which a person without a son would adopt a hasband's relative with the same last name in order to preserve the family line to be the most ideal situation regarding adoption. So, they started to make laws which restricted certain cases that were allowed in previous periods. Such laws diffrently defined Suyang adoption and Shiyang adoption in legal terms, and demoted the legal status of children who were Shiyang-adopted. First they established a limit with regard to how much of the foster parents' property that a Shiyang children(侍養子女) could inherit. And they did not establish the time period a person should observe in mourning(服喪) their deceased Shiyang parents(侍養父母), while a three-year mourning period was established for persons mourning their Suyang parents(收養父母).
As we can see, instead of imposing forcible legal actions upon cases of adoption that were considered inhibitive to the establishment of a proper culture of Confucian-based memorial services, the leaders of the Joseon dynasty differently treated Suyang cases from Shiyang cases by the person's age of adoption, and chose an indirect path of lowering the legal status of the Shiyang children. Such efforts of legislation regarding Suyang practices and Shiyang practices which continued during the early days of the Joseon dynasty was a step that was followed by the enactment of the Heir-naming law. And under these circumstances, adoption of Suyang children and Shiyang children prevailed during the 15th century.
If we examine the Suyang and Shiyang adoption practices at the time, we can see that relatives of either the husband or wife, or even an entity who did not bear any relations whatsoever to the couple, were considered as general candidates to be adoptees.
First, there were cases in which people who were actually related to the couple were adopted. In these cases, both of the couple would choose to adopt a person from each of their relatives without considering either a paternal relative or maternal relative more favorably. There were two reasons for this kind of fashion in adoption. Traditions from the Goryeo dynasty period, which determined the nature of relationship solely based upon the level of proximity between relatives without any particular inclination either to paternal or maternal relatives, were still very much alive. Among people there was a tendency of trying to give their properties only to descendants of certain ancestors from which they inherited the property in the first place, and to no one else. Because of such customs, both of the married couple would respectively show the tendency of choosing candidates of Suyang or Shiyang adoption, with people who were more closely related to them.
And in cases in which people who were not related to the married couple were adopted, adoption was being freely practiced as well. Usually they were chosen by the married couple whose intention was to maximize their interest, or a couple who practically needed such adoption, or a couple who considered the adoptee as a personally close to them.
There were various objectives displayed in Suyang and Shiyang adoption practices. Among members of the upper social class, there were three major reasons for adoption. First, adoption was arranged not only to raise a young child, but also because the adopters expected the child to pay respect to them when the child grew up, and to hold funerals and memorial services when the foster parents were gone. Second, between several of the royal family members, like the females, and princes or sons of the princes of the current king, an adopted relationship was arranged between them, in order to secure peace and unity inside the royal family. Similar relationships are found among ordinary people as well. Between the legitimate sons or daughters(嫡族) of a person, and the concubine(妾) of that person, an adoption-like relationship used to be formed, in order to establish a stable and peaceful relationship. Third, there were cases in which princes or princesses, or sons and daughters of powerful houses, became adopted children of other houses. In such cases, the adoptees, or the house of the adoptees, were able to secure an economic income and property inheritance, while the adopters secured a promised future in political or economical ventures.
As we can see, during the 15th century, the practice of adoption was not much restricted in terms of whom to adopt, or why to adopt. There were at least four reasons for this prevailing of free adoption practices. First, although by legal terms Suyang and Shiyang were considered differently, there were no legal definitions regarding the nature of qualification for Suyang children and Shiyang children. Second, the stability of the relationship between foster parents and adopted children was not protected by the law. Third, in cases of Suyang or Shiyang adoptions, the relationship between the children and their biological parents was considered to be more important than the relationship between the children and their foster parents. Fourth, even though the social class occupied by the foster parents and the social class occupied by the adopted children were different from each other, the status of the parents did not affect the status of the children. So, under these circumstances, Suyang or Shiyang adoptions proceeded pretty much freely.
And at the same time when these adoptions were prevailing, the so-called Heir-naming law(立後法) was enacted in the 19th year of King Sejong's reign. This marked the aggressive legislation of a law meant for the establishment of a Confucian-based memorial service system for the houses without sons. This was a meaningful legislation as the law was meant to provide people, who wished to establish an heir for one's house, with a legal standard or basis of naming such heir, especially in a time period in which relatives of the husband with the same last name were not actively sought for as a candidate for adoption yet. When this law was legislated and enacted, the candidacy for heir-naming(立後) was defined to fall to the son(支子: other than the first one) or a grandson-level relative(族孫), among the husband's relatives with the same last name. Naming a brother figure or a senior(尊屬) as an heir was banned by this law. Yet in the final version of『Gyeongguk Daejeon(經國大典)』, the Eulsa-year Code of Law(乙巳大典), naming a grandson-level relative as an heir was banned as well. So, only a son with a position appropriate in terms of the So-Mok(昭穆) concept among husband's relative with the same last name was defined as a lawful candidate for heir-naming. And the people were instructed to seek for the government's permission in individual heir-naming processes. The central government intended to supervise such practices, and urge the public to abide by the law. So, people who wished to name 'a successor by the Hier-naming law'(繼後子 : 'a successor'), was required to submit a Soji(所志) to the Yejo office, and receive a Gyaehu Iban(繼後立案). But the Heir-naming law was not a law enacted to enforce heir-naming, and was only a law enacted to provide legal basis for such action. So the government also enacted another law to ensure the legal status of the successor as a legitimate heir(嫡子承重子), in order to also successfully land the Heir-naming law.
Other legal actions were also taken to facilitate the establishment of the Heir-naming law. Right after legislating such law, King Sejong let the world know the enactment of the Heir-naming law by ordering the establishment of successors for the deceased royal family members and meritorious vassals(功臣) who had no sons to succeed them. And after King Jungjong's enthronement, which kicked Yeonsan-gun out of the throne, even the heir-naming practices which were considered to be beyond the legal boundaries of the Heir-naming law were granted by special orders from the King. This led to the so-called 'Outlaw heir-naming'(法外立後) practices. Outlaw heir-naming was granted because it was necessary to secure the successors for certain people who were politically purged during the reign of King Yeonsan-gun, but what started as a temporary act of benevolence on the King's part, became a method of encouraging people to name an heir of their own.
Even long after the enactment of the Heir-naming law, there were still only few people without sons who attempted to name a successor. But when the Confucian-based memorial services became a norm inside the Joseon society, the number of people who tried to name a successor grew. The reason why not so many people without a son named a successor during the 15th century even after the enactment of the Heir-naming law was because the aforementioned nature of kindred relationship, and the customs regarding property inheritance at the time. Especially the restrictions upon offering property to others who were not descendants of the same ancestors were an inhibitor to the increase in cases of heir-naming. Because of such restrictions, the wives would not agree to have the successor inherit all the properties of the married couple, which was composed of not only the husband's property, but also the wife's property. Yet as Confucian-based memorial service became the major trend of the society, and people grew more eager to secure a person who would steadily take charge of holding memorial services for their own, heir-naming became a necessary norm as well.
And such changes can be confirmed by the changes occurred in the fashion of Suyang and Shiyang adoptions. From the property distribution records(分財記) of the 16th century, there are cases in which a relative of the husband was named as an adopted child(either Suyang child(收養子) or Shiyang child(侍養子)) and inherited not only the property of the husband, but also part or all of the property of the wife. In such cases, the reason of adopting a child was to have him take charge of the memorial services(奉祀), and take the role of an heir in the future. People came to want more strongly to have a stable descendant who would hold memorial services for their own, and the principle of not giving property to anybody except the kindred descendant was not being observed enough. This also shows that people were being less reluctant to search for a successor. So, widows started to seek for successors after the death of their husbands, and cases in which Suyang or Shiyang children were named as successors also increased.
People also did not want to have the child of a concubine serve as an heir to their houses, and that led to the increase in heir-naming practices as well. The directive inside 『Gyeongguk Daejeon』, which allowed heir-naming only when one failed to have a son both from the legitimate wife and a concubine, weakened during the 16th century, and people who did not have a son from the legitimate wife yet actually had one from the concubine, tended to name the successor with a legally ensured status who would steadily hold memorial services for their own, instead of having the son of a concubine to hold memorial services for them.
Such process of the general increase in heir-naming practices, indicated that the paternal-centric order in houses without heirs were growing stronger than ever.