The Family in the History of Philosophy

Vittorio Hösle | PASS Academician

The Family in the History of Philosophy

The family is, like other social institutions (economy, politics), based on biological needs. Organisms need to reproduce, if their species is to last, since individuals are mortal. In the case of humans, however, it is not simply physical but cultural reproduction that is involved. Humans’ physiological vulnerability is increased by their long dependence on education to become familiar with culture, beginning with language. Furthermore, human sexual needs are detached from seasonal cycles and thus render long-term commitment to a partner more likely. “Genetic egoism” – as the only way in which altruism could develop1 – also explains the importance of family relationships among humans.

However, the definition of kinship always involves cultural practices, such as matrilinear and patrilinear descent rules. The long relationship between the parents in raising the children creates a special, personal bond, which is usually expected to survive the common task of the education of the children. This bond and its sexual root explain why families rely on emotions more than other social institutions – a fact that renders their legal regulation considerably more difficult and precarious than in the case of, say, a limited company. In most cultures the family needs strong moral, legal, and sometimes even religious sanctions.

The natural basis of the family does not exclude the historical evolution of the institution. With the evolution of modern society, particularly thanks to increased mobility of location and social standing, individualization, and integration of women into the workforce, the extended and multigenerational family has been reduced since the age of the bourgeoisie to the nuclear family. Doubtless, this too is now endangered.2 Some of the main factors that led to changes in family law are the question of who has the right of entering into marriage (the spouses or their families of origin, which remain crucial even after marriage, unlike in the animal world), the rights and duties of the spouses within the marriage (and, in the case of divorce, against each other after the marriage), the duties toward children, and the rights and duties of the latter.3 Not being a historian, however, I will not speak of the social and legal history of the family. I will focus on the four theories of the family developed by philosophers who are arguably the greatest – namely, Plato, Aristotle, Kant, and Hegel – and then discuss the changes in our understanding of gender roles that began to emerge in the nineteenth century and that have had an enormous impact on the contemporary reality of family life.

Since there are many other theories of family, the jump from the 4th century BC to the 18th century is too abrupt. I will therefore quickly mention some of the most relevant changes that occurred between Aristotle and Kant, not least the Christian transformation of the concept of the family even if it is connected to theological ideas, which transcend my philosophical competence. But I will spend more time with my four authors not only because of their insightfulness but also because they represent four paradigmatic views: Plato in the Republic the negation of family, Aristotle a biologically-rooted doctrine of social institutions, Kant a contractualist understanding of marriage based on an absolute sense of obligation, and Hegel the attempt of a reconciliation of the ancients and the moderns.

Whoever studies philosophical thought on the family cannot help being struck by the fact that most who developed theories about it were not simply men (which, given the educational system of the time, can easily be explained) but bachelors. This holds obviously for the Church Fathers and the scholastics but also for Hobbes, Locke, Hume, and Kant. It is impossible to gainsay that the contrasts between Plato and Aristotle on the one hand and between Kant and Hegel on the other are connected to the psychological fact that Plato and Kant, unlike Aristotle and Hegel, never lived a married life. Only bachelors could devise theories so distant from experience.Yet they remain fascinating from an intellectual point of view. 


The first great philosophical theory of the family originates as a critique of the family in its normal understanding – I mean Plato’s conception of the communism of wives in the Republic. In Book IV, Socrates mentions that education and reproduction (in this order, which is obviously axiological, not chronological) are the most important thing in the establishment of an ideal commonwealth, compared with which all other matters pale (423e), and only vaguely alludes to the communist ideal (which he also defends for material goods). But in the fifth book, when he tries to shift to a new subject, Adeimantus forces him to return to that topic, the centrality of which he reiterates (449e), while Adeimantus’ brother Glaucon insists on the fact that early childhood education is the most demanding one (450c). Socrates begins his reflections with a defense of the fundamental equality of men and women – while the latter are weaker, they are not in principle different (455d f.). Therefore, the education of men and women should be the same, which is not only feasible but also desirable (457a).

Note that Socrates does not speak about the whole society but only about male and female guardians, a subset of which are the philosopher kings (457b). This condition holds of course also for the further thesis that all wives should be in common so that no father could know his child, nor the latter his father (457c f.). Socrates wants to discuss first the desirability and only later the feasibility of the plan. He starts with the necessity of a eugenic organization of reproduction – what breeders do with their animals, humans should do a fortiori with their own species. First of all, the number of the population should be kept as constant as possible (460a). The best males should mate with the best women and the worst with the worst.Yet the descendants of the latter should not be raised (459d, 461c). This, however, must be organized in such a way that the mating couples are not able to understand that the concrete intercourses granted to them by lot are not the result of chance but in fact manipulated by the rulers (459c; on “noble lies” see 382c ff. and 414b ff).

The rulers, by the way, may be both male and female (460b). It is crucial that generating and bearing occur for the city-state (460e). The age span in which men and women can reproduce is strictly determined (460d ff.); every single intercourse must be permitted by the rulers but only as long as there is the possibility of reproduction; afterwards there are no limits, as long as there is no risk of incest (461b f.). Babies have to be quickly taken away from their mothers and delegated to wetnurses (460c f.). The decisive argument for this model is the unity of the state. It is supposed to be endangered when “mine” and “not mine”, as expressed by different people, do not refer to the same objects. Like the pain of one organ is felt by the soul of the whole organism, so the pain of one citizen should be felt by all (462c f., 464b). Precisely this will be achieved by the communism of wives, for every citizen could now be a sibling, parent, or descendant (463 c). This will increase reciprocal help and decrease inner strife (464d ff.).

While one can understand why the Platonic conception might appear appealing in a world in which conflicts between different γένη, φρατρίαι, and φυλαί could endanger political peace and limit the sense for the common good of the city-state, it is not now. First, our modern concept of individual rights finds the idea of some rulers manipulatively organizing the breeding of the people repulsive. Against the argument that one should treat humans no less carefully than animals, it is easy to object that because humans are not simply animals their reproductive decisions have to be left to themselves. Their manipulation is perhaps even more morally heinous than physical enforcement would be, and its public defense in a book means that Plato’s Republic would be forbidden in the ideal state. The explicit defense of the elimination of children not regarded as worthy to live is incompatible with the later Christian concept of human dignity, even if the exposing of children corresponded to a widespread social reality in the ancient world.

Second, even if one subordinates individual rights to the common good, as the ancients did, it is absurd to assume that the elimination of concrete family relations would lead to some universal brotherhood within the city. Brotherhood can only be expanded if one has experienced it. This means the concrete relationship of intense affection and reciprocal responsibility that can only be built up among members of a small group who come to know each other in an intense way from their childhood on. The result of the Platonic education system would not at all be universal brotherhood but universal indifference. As the important neo-Confucian philosopher Tongdong Bai has recently written in an astute comparison of Confucianism and Plato’s political philosophy: “Without family, ‘father and mother’ and ‘brothers and sisters’ carry no significance, and they only gain significance when filial affection for family members is cultivated in a family environment. Or, using the metaphor in 1.2 of the Analects, the big family in the Republic is like a rootless tree”.4

Still, one can recognize that some of the Platonic ideas have become reality in later human history. The strict difference between the reproductive behavior of the elites and the masses also characterizes the distinction between hierocracy and ordinary faithful people in the Catholic Church. While of course Plato’s guardians do not live a celibate life but function rather as selected stallions for a new breed of men, their renunciation of a normal family life somehow anticipates the celibacy of the Catholic clergy. The clergy, however, has the explicit task to grant sacramental status to marriage and thus legitimize normal family life, which in the Republic is not dealt with at all but looked at with suspicion and contempt. But in the Laws, where the function of the philosopher kings is reduced, normal, non-communist family relations based on an individual commitment of the spouses are an explicit topic; indeed, marriage laws are regarded as the basic laws (721a). The state is conceived as a collection of households, not, as in modernity, of independent individuals. Therefore, it is explicitly stated that the choice of the spouse should aim not at what is agreeable for oneself but good for the state (773b). Even if it is more tiresome to live together with someone with a different character, such a bond prevents a polarization of society into different groups homogenous in themselves but incompatible with each other (see already Statesman 310b ff.). Plato recognizes that a legal obligation cannot work in such a case, but he hopes for what today would be called moral suasion (773d). However, there is a legal duty to marry in general, and after the age of 35 men are fined and deprived of honors if they refuse to do so (774a ff.).5 This is explicitly understood as a religious duty – one has to partake in the eternal essence and preserve new servants, who can replace oneself, for the god (773e, cp. 721 b ff. and Symposium 207c f.).

In many aspects, the Laws continue the “proto-feminist” program of the Republic. Certainly, neither work teaches an equality between man and woman but both demand far more rights for women than existed in any Greek state. Women are entitled to political offices and subject to military service, even if the age limits are different (785 b). Women should neither be treated as slaves, as among the Thracians and other barbarians, nor restricted to the home, as in Athens, but be able to defend their country (805 d ff.). For violations of sexual norms, the punishments are the same for men and women (784 d f.) – an impressive deviation from the double standard that was valid even in several legal systems of Western Europe until after World War II.6 Still, the similar position concerning public law is not matched at all by the rules of civil law. Women cannot inherit or own property and are under the tutelage of a male relative. Even when a father has only daughters, he has to bequeath his property to the son-in-law (923 e). Normally, it is the male relatives who choose a woman’s husband (774e). Only unmarried women are permitted to bring civil actions (937b f.). Thanassis Samaras rightly asks: “How can women be reduced to such a subordinate role within their family and at the same time become the warriors and active citizens that Plato wants them to be? The psychological implausibility of this expectation indicates that the philosopher never asked himself this question”.7


Aristotle’s approach to the family is, as is well known, radically different from Plato’s. Not only does he reject communism of wives and property with excellent arguments in the second book of the Politics, in its first book he develops his own theory of the qualitative differences between the various social institutions. His central idea is that οἰκία and πόλις, household and city-state, do not only differ quantitatively; for if their difference were only in the number of members of the social institution, then there would be no difference between a big household and a small city-state. But in reality their difference is based not on size but εἴδει, on their essence (1252a20). Certainly the introduction of an intermediate social institution, κώμη, the village, between οἰκία and πόλις (1252b15 ff.), somehow obfuscates his argument; for this seems to be a necessary step only in order to account for the genesis of the city-state, since the village does not play any role in the actual workings of the already existing city-state.8 One can imagine a city-state without surrounding villages, even if they certainly did exist in most ancient city-states. But according to Aristotle, one cannot conceive a city-state without households – and one cannot imagine households in which people live well without the surrounding frame of the city-state. The basis of the οἰκία is the biological need for reproduction. It would be, however, misleading to interpret συνδυάζεσθαι (1252a26) in the context of the Politics as mere mating, a meaning which it has in the biological writings (for example Generation of Animals 746b12). The use of the term in the great treatise on friendship in the Nicomachean Ethics 1162a15 ff. shows that a bonding of friendship is meant that transcends the mating act and forges a relationship of particular intensity.

Still, this relation is deeply asymmetrical. This is partly rooted in Aristotle’s developmental biology;9 and in the Politics it becomes manifest when the inequality between man and woman is compared with that between master and slave (1252a30 ff.). Certainly, the two inequalities are not the same; for nature does not use the same object for different purposes, and it is only barbarians who treat women and slaves in the same way, thus giving the Greeks the right to treat barbarians as slaves (1252b1 ff.). But the specific difference between the two inequalities does not change the fact that the household, unlike the city-state (1255b16 ff.), is the realm of asymmetric relations, albeit in very different degrees. (And Aristotle does not contemplate female activities in the polis). This holds for all the three relations that constitute it – the one between husband and wife, the one between parents and children, and the one between master and slaves, without which the household would not be complete (1253b4 ff.). Certainly the relation between master and slave, which Aristotle discusses most extensively, defending the doctrine that there are slaves by nature, is the most asymmetric – it is a form of despotic rule (δεσποτική, 1259a38). 

The rule of the father over the children, on the other hand, is called “royal” (βασιλική, 1259b11); for the father rules like the king with friendship and based on the authority of age. But does not the characterization of the relation between the spouses as “political” (πολιτικῶς, 1259a41) point to symmetry between husband and wife? Not really, for even if Aristotle clearly conceives it as the least asymmetric relation within the household, he still calls the form of rule in a household monarchical (1255b18 f.), he asserts the superiority of the man over the woman, whenever their relation is not against nature (1259b1 f.), and he insists on the fact that, unlike in the alternation of rulers and ruled citizens in a polity, the superiority of the husband always holds (1259b9 f.).

The asymmetry of the relations within the household does not challenge its natural place among social institutions. In fact, the critique of Plato’s communism in the second book of the Politics also contains a sharp rejection of the communism of wives. First of all, Aristotle rightly teaches that the unity of the state is not the supreme goal; for in this case, the city state should become a household, and the household an individual (1261a17 ff.). A maximal unity of the city-state would thus abolish itself as a city-state. Furthermore, a city-state does not only presuppose a plurality of subjects, but also their being different, because only by division of labor can a city-state achieve self-sufficiency. But even if we granted the goal, the communism of wives would not be the right means to achieve it.The abrogation of the family would not increase the identification with the state.The meaning of “mine” would change; instead of extending the normal love for one’s own children to others, the love granted to the thousands who would now be called “one’s own children” in a collective, not a separate sense, would be completely diluted (1261b16 ff., 1262b17 ff.). It is better to be one’s private nephew than a son in this collectivist sense (1262a13). The heterosexual Aristotle uses the occasion to reproach Plato for his condoning homoerotic love, which would be particularly inappropriate between brothers and fathers and sons (1262a32 ff.). (Aristotle seems to ignore the late Plato’s condemnation and prohibition of homosexual acts in the Laws 636b ff., 836a ff., 838e, 841d). Since the community of wives could not prevent people from trying to find out who really is their child, it would create only animosities; and it should be favored only among the lower classes, if the purpose were to dominate them more easily due to their quarrels among themselves (1262a40 ff.). Aristotle, however, considers it a political error to stoke conflicts in some parts of the population. And he foresees many conflicts in the transfer of children from one class to the other, as planned by Plato. 


The most important event in the evolution of the Western doctrines of marriage is the rise of Christianity. On the one hand, unlike the pagan religions, early Christianity, inspired by the evangelical counsels,10 subordinated married life to celibacy. The defense of marriage as an equally legitimate form of life became increasingly a minority position – think of Jerome’s ferocious attacks against such a position, upheld by Jovinian, in Against Jovinianus (Adversus Jovinianum). On the other hand, the Church never condemned marriage, as Montanus and later Priscillianus, who at the same time defended an equality of the sexes, did. On the contrary, she bestowed a particular dignity on marriage, beginning with Paul’s comparison of husband and wife with Christ and the Church (Eph. 5:23 ff.) – a comparison, which still excluded symmetry between the spouses, since Christ and the Church cannot be considered equal partners. Based on this Pauline passage, Augustine ascribes sacramental character to marriage and justifies thereby its indissolubility.11 Marriage remained among the sacraments, when they were limited to seven in the Sentences by Peter Lombard and this was confirmed by the Fourth Council of the Lateran in 1213.

The Christian restriction of legitimate sexuality to marriage slowly12 contributed to a revolution in sexual mores, which would be reversed on a general theoretical level only in the course of the 20th century. The new ideas were revolutionary particularly if compared with the form of life that the upper classes of Rome, including the women, had begun to adopt in the 1st century BC (suffice it to mention Ovid’s Ars amatoria). But even in relation to Antiquity as a whole, some norms of Christian sexual ethics were quite innovative. The consensus among the synoptics makes it obvious that the prohibition on divorce, which is permitted in Judaism and had become frequent in the Roman Empire, goes back to Jesus himself (Mk 10:2 ff., Mt 19:3 ff., Lk. 16:18); it is reiterated by Paul (1 Cor 7:10 f.), who appeals explicitly to the Lord and distinguishes from his teachings his own additions. In the vice list of the Didache (2.2), fornication, adultery, pederasty, abortion, and infanticide, the latter quite widespread in the pagan world,13 are mentioned among the things belonging to the way of death (the first three are also found in Paul’s analogous lists, 1 Cor 6:9 f., Gal 5:19 ff., 1 Tim. 1:9 f.).

Religious texts express and shape moral sensibilities but rarely argue. The later patristic-scholastic tradition, however, tried to give rational arguments for the specific Christian understanding of the indissolubility of marriage. Aquinas is important because he not only mirrors the canon law of his time but also combines a defense of the sacramental nature of marriage with an appreciation of the institution as natural that owes much to Aristotle. The two main natural ends of marriage are the reproduction of the species and the reciprocal help of the spouses. Aquinas explains the lifelong nature of the commitment with the length of the time needed for the raising of a child, i.e., with what today we call the altriciality of humans. He even gives some examples from the animal world: Mating is sufficient as an interaction between the parents when the newborn animal can feed itself or can be fed by the mother alone; but when the cooperation of both parents is needed, we see, as in some species of birds, a cooperation of both parents (Summa theologiae Supp. q. 41 a. 1 c.). The diverse forms that marriage finds in different cultures do not change the fact that it is an institution rooted in nature, since natural law can be differentiated according to external circumstances (Supp. q. 41 a. 1 ad 3, q. 42 a. 2 ad 1). Marriage was instituted before the Fall by God, but Moses added the prohibition of incest (Lev 18:6) – a prohibition that was earlier cleverly justified by Augustine with the argument that the obligation to marry outside of the family increases the number of bonds of friendship that connect people.14 The third institution of marriage occurred within the New Covenant, with the sacramental interpretation of marriage as pointing to the commitment of Christ and the Church.

Finally, there is also an institution by civil law, motivated by the mutual services of the spouses. Marriage is thus a natural, civil, and sacramental institution (Supp. q. 42 a. 2 c.). The efficient cause of marriage is the consent of the spouses (and thus a form of contract), which has to be expressed verbally, even if words without accompanying consent are not sufficient to constitute marriage. Aquinas anticipates John Langshaw Austin’s theory of speech acts when he states that the words of the spouses during the wedding ceremony both signify and effect marriage (Supp. q. 45 a. 3 c.). A public ceremony is not necessary for the validity of marriage, even if it is usually sinful to marry in secret (Supp. q. 45 a. 5 c.). Forced consent invalidates a marriage; even parents cannot force their children to consent to marriage (Supp. q. 47 a.6). On the other hand, slaves do not need their master’s consent to undergo a valid marriage; even positive law cannot change this, since positive law cannot break natural law (Supp. q. 52 a. 2 c.). The sacramental dimension of marriage sanctifies the institution by granting it indissolubility and is, as already in Augustine, the highest of the three goods of marriage, descendants and mutual faithfulness being the two other ones (Suppl. q. 49 a. 3 c.).15 The divorce of the spouses in the case of adultery is permitted – though not mandated – since faithfulness has been violated; yet this does not entail a right to remarry. Aquinas’ evaluation of adultery from the side of the husband and the wife respectively is interesting. From the point of faithfulness, both forms of adultery are equally sinful; but from the point of view of the descendants, the woman sins more (Supp. q. 62 a. 4 c.). Aquinas seems to have in mind that only the adulterous wife obliges her husband to raise children not his own – an argument often used in the tradition to justify the double standard. But it is still remarkable that Aquinas insists on equal treatment concerning the violation of faithfulness. From a sociological point of view, there is little doubt that for many centuries the belief in the sacramental nature of marriage strengthened the sense of commitment of the spouses. A failed marriage would symbolize the loss of Christ’s unity with the Church and thus of one’s own salvation. 

What led to the decline of the Catholic conception of marriage and the rise of a new one? The most decisive force was certainly the rise of liberalism as a political philosophy, focusing on the rights of individuals who engage with each other according to their needs and desires in the form of contracts. But without Protestantism, the liberal revolution would have hardly occurred. Luther denied the sacramental nature of marriage, which for him is a social estate, and Calvinism followed suit, even if the late Calvin offered a covenant theology of marriage.16 An important consequence of this desacramentalization is drawn by John Milton in his four tracts defending divorce, which challenged the Anglican Church, which continued to follow Canon law. Milton’s central claim in the first edition of The Doctrine and Discipline of Divorce is “That indisposition, unfitness, or contrariety of mind, arising from a cause in nature unchangeable, hindering and ever likely to hinder the main benefits of conjugal society, which are solace and peace, is a greater reason of divorce than natural frigidity, especially if there be no children, and that there be mutual consent”.17 His argument is based on the principle of Christian charity, which should not condemn people to unhappiness. He furthermore uses the argument that even more than sexual impotence (which Aquinas recognizes as a legitimate reason for declaring a marriage invalid, as long as it preexisted matrimony and the wife had not been informed18), incompatibility of characters justifies the dissolution of marriage and should not prevent a second marriage. Otherwise, sexual intercourse is considered more essential to marriage than the community of minds, while in fact the main purpose of marriage is not intercourse but a happy conversation that overcomes loneliness. Milton goes even so far as to downplay the responsibility for the children from a loveless marriage since they are “children of wrath” and almost like bastards (52). He rejects the natural objection that the compatibility of characters should be studied before marrying by saying, probably correctly in his time, that before marriage the betrothed could not freely spend time together and therefore the more serious and timid characters are more likely to err than womanizers (47). 

Milton is rightly regarded as a “proto-liberal”: His ideas concerning the separation of state and church, the freedom of the press, the right to resistance against the government are no less innovative than his defense of divorce. It does therefore not come as a surprise that the father of modern liberalism, John Locke, expands the Miltonian idea. The family is important in the Two Treatises of Government, because the first, directed against Robert Filmer’s Patriarcha: or the Natural Power of Kings (which was published posthumously in 1680), completely rejects any attempt to conceive of political power according to the model of a patriarchally ruled family.19 But the second Treatise tries to show that Filmer’s concept of family is wrong even if we abstract from its purported political relevance. The power of the husband is not that of an absolute monarch, even if the last determination in cases of conflict “naturally falls to the Man’s share, as the abler and the stronger”.Yet the wife retains the right to separate from him and sometimes even to take the children with her. This may depend on the customs or laws of the country or on a contract made between the spouses; for Locke explicitly recognizes the possibility of marriage contracts as flexible as any other voluntary compact. They need not be always for life. Though the long phase of dependence of children necessitates that human marriage be more lasting than the bonds of other creatures, Locke suggests to inquire “why this Compact, where Procreation and Education are secured, and Inheritance taken care of, may not be made determinable, either by consent, or at a certain time, or upon certain Conditions, as well as any other voluntary Compacts, there being no necessity in the nature of the thing, nor to the ends of it, that is should always be for Life”.20

Locke goes farther than Milton towards contractualism. What is missing in him, however, is the proto-romantic element that is so powerful in the poet of the love of Adam and Eve in Paradise Lost. The bachelor Locke has no sensibility for the specific erotic dimension of marriage, the desire to find a kindred soul, which for Milton antecedes the sexual need and the wish to reproduce. This desire is probably not an anthropological constant but developed slowly in the Western tradition. The discovery of an autonomous erotic realm in the Roman poetry of the 1st century BC and the new evaluation of women’s role brought forth by Christianity led in the 12th century, initially in France, to a new romantic ideal of the love between man and woman. This ideal both inspired and endangered the traditional institution of marriage, for it led to expectations that are rarely fulfilled. But the new ideal of courtly love was limited to the elites. Only in the 18th century did it spread to the bourgeoisie. Rousseau’s Julie, ou la nouvelle Héloïse forcefully expresses the idea that marriages should be based on love, not on economic or class considerations.

Despite their deviation from traditional Christianity in the question of divorce, Locke and obviously Milton are sincere Christians. It is worth noting that the strongest defense of the indissolubility of marriage in the British Enlightenment stems from an author who is certainly not a Christian. I refer to David Hume and his essay “Of Polygamy and Divorces” of 1742. On the one hand, Hume is much better informed of the varieties of reproductive arrangements that humankind has brought forth in its history than the authors whom I have mentioned up to now. (Hume also considers ecological factors in order to explain the different behavior of various animal species). He writes at a time in which both historical and geographical knowledge had increased prodigiously, and sociology had begun to rise as a discipline no longer dependent on ethics and normative political philosophy. In 1744 GiambattistaVico published the last edition of his Scienza nuova (New Science), in which he develops the foundations of a general theory of human culture. In the fourth chapter of the second book, “On poetic economy”, he gives an extremely realistic account of the brutality of archaic family life. Four years later, Montesquieu’s De l’esprit des lois (The Spirit of Law) follows suit, whose 23rd book deals with family law and demography in a comparatist spirit. But all his ethnographic and historic erudition does not change Hume’s commitment to life-long monogamy. He intelligently states the arguments both for polygamy and divorce but staunchly rejects them. Polygyny destroys the equality between the sexes and renders both romantic love and friendship impossible. “Barbarism, therefore, appears ... to be the inseparable attendant of polygamy”.21 With regard to divorce, it seems cruel to deny to hearts not made for each other another chance; the insecurity of marriage, furthermore, forces the partners to exert themselves to keep the institution alive. Hume does not contest the partial validity of these two arguments but thinks that they are trumped by the following considerations: first, the fate of the children upon the separation of the parents; second, the stabilization by institutional constraint of friendship, which should be the basis of marriage, not volatile erotic attraction; third, the natural connection of an unlimited temporal horizon with a union as total as that of marriage.


The liberal, contractualist transformation of marriage achieved its peak, perhaps surprisingly, in the German tradition, when in 1791-92 Wilhelm von Humboldt wrote his Ideen zu einemVersuch die Grenzen derWirksamkeit des Staats zu bestimmen (Ideas for an Essay to Determine the Limits of State Action). The work, which influenced John Stuart Mill’s On Liberty, was published in its entirety only posthumously in 1851, but the exposition of Humboldt’s ideas on marriage can be already found in the chapters printed in 1792 in Schiller’s Neue Thalia. Humboldt’s whole work is committed to the principle of fostering the forces of the individual, and he considers the state usually harmful to this aim. He thus defends a position similar to those of the later libertarians, who want to reduce the state to the function of safeguarding internal and external security. In this context, Humboldt refuses to concede to the state any business in the regulation of marriage. While he eloquently defends the difference and complementarity of man and woman, he insists that the individual desires and needs among partners are so varied that a numerus clausus of types of right is inappropriate. The partners should be allowed to form and modify contracts at their will, not subjected to a few prescribed forms. The roots of his conception are romantic – the essence of marriage is the relation between the spouses, children only a consequence of it, and the essence, not the consequences are crucial. He furthermore trusts that individual inclinations and customs will substitute for laws.22 While Humboldt is certainly right that there a lot of things in a marriage that cannot be enforced by legal mechanisms, his cavalier attitude with regard to the rights of the children and those of the parent who has invested most time with the child, renouncing a career, is quite unsettling. And, of course, the reader wonders whether Humboldt would also accept a temporal limitation of a marriage contract and even a ménage à trois (or more).

The importance of Kant’s doctrine of marriage consists in the fact that, one the one hand, it continues the individualistic tradition, while on the other hand it remains committed to the principle of the indissolubility of marriage. He does this somehow in accordance with his ethics, whose concrete contents mostly correspond to liberal convictions, but which are based on a categorical imperative that transcends our inclinations. Every hint to erotic romanticism is absent from his theory of marriage, which is unfolded only in the first part of the Metaphysik der Sitten (Metaphysics of Morals), the “Rechtslehre” (“Doctrine of Right”), not in the second part, the “Tugendlehre” (“Doctrine of Virtue”), even if the latter culminates in a doctrine of friendship. Unlike Aristotle, Kant deals with the family exclusively within a doctrine of natural law, not within a moral theory or a theory of social institutions. The doctrine of marriage, parenthood, and of the head of the household belongs to the part on private right, which is followed by a part on public right, dealing with the state, international, and cosmopolitan law. The second chapter on private right is subdivided into “Vom Sachenrecht” (“On property right”), “Vom persönlichen Recht” (“On personal right”, dealing mainly with forms of contractual obligations) and “Von dem auf dingliche Art persönlichen Recht” (“On Rights to Persons Akin to Rights to Things”). Reminiscences of the triadic subdivision of Roman law in personae, res, actiones, listed, for example, in the Institutiones of Gaius, probably play a role in Kant’s subdivision but he clearly wants to conceive the third stage as a synthesis of the two earlier ones. Why? The household according to Kant is still characterized by the three relations ascribed to it by Aristotle, even if the slaves have now been replaced by servants. The spouse, the parents, and the master can retrieve the spouse, the children, and the servants that have eloped and bring them back as if they were physical objects (AB 108, 115, 116).23

What is marriage? Kant’s notorious definition in § 24 conceives it as “union of two people of different sex for the lifelong reciprocal use of their sexual properties” (AB 107). Reproduction is not considered a necessary part of the marriage contract, for otherwise the marriage would dissolve with the loss of the capacity of reproduction. It is not at all clear why on the basis of this definition an analogous contract between people of the same sex should not be allowed, even if Kant utterly condemns homosexuality and bestiality as unnatural (AB 106 f.). Kant’s main interest is to show that such a contract can only be legitimate if it is lifelong (§ 25). The central argument is that the person who offers himself or herself to another as an object of sexual enjoyment objectifies himself or herself; and that this can only be prevented if he or she can do the same thing with the partner. Since, however, in an organism every limb is connected with the whole person, such a use of the sexual parts leads to the reciprocal acquisition of the whole person. Needless to say, it is not clear why reciprocal instrumentalization should eliminate the morally questionable nature of instrumentalization, even if one can agree that asymmetry added to instrumentalization makes it worse. Kant conceives marriage primarily from the sexual act and then tries to limit the latter to marriage, instead of conceiving marriage as the appropriate institutional frame for reciprocal love within which sexual intercourse then loses the character of objectification.

What is progressive in Kant is something different, namely, first, the strong insistence on the symmetry of the relation between the spouses.24 Only monogamy is supposed to fulfill this condition (in fact, the latter excludes only polygyny and polyandry but not necessarily a marriage between two men and two women; here an additional argument from the totality of the relation is required). Kant rejects not only concubinates, but also morganatic marriages. Still, the symmetry between the spouses is compatible with the economic prerogatives of the husband, if his natural superiority is better fitted to the administration of the common aims of the household (AB 110), and it is undeniable that Kant’s reflections on the differences of the sexes in the second section of the second part of the Anthropologie in pragmatischer Hinsicht (Anthropology from a Pragmatic Point of View) express a deeply ingrained misogyny (an objection that can only tempered by the reflection that Kant’s view of humanity in general is bleak). Like in the doctrine of the Catholic Church, in Kant’s theory of marriage too the latter becomes valid not simply through the marriage contract but through its consummation (§ 27). The procreation of children (which according to Kant occurs with conception) engenders, secondly, an absolute duty to raise and educate them, both pragmatically and morally, until their emancipation. No infant exposure, infanticide, or abortion is permitted, whatever social utility may be expected from such an act. Since, however, there can be no contract between parents and children, the latter only have a moral, not a duty according to natural law to return the benefits they enjoyed from their parents (AB 114).

Concerning servants, Kant, thirdly, insists that their status cannot be that of slaves, not even if they had sold themselves by a free contract into slavery. Such a contract would be invalid because it would deprive a person of personhood and thus of the duty to respect the contract (AB 116 f.). Neither are serfdom nor an explicit lifelong commitment permissible forms of service. Even if slavery were justified in certain cases as a form of punishment, the children of slaves would be born as free persons, and the duty to raise them would devolve from their incapacitated father to his owner.


Hegel’s doctrine of the family is in my eyes the richest and philosophically most complex one among the classical theories. Even if Johann Gottlieb Fichte, to whom I will return, follows Kant’s bipartition of practical philosophy into philosophy of natural law and ethics, he insists in the Grundlage des Naturrechts nach Principien der Wissenschaftslehre (Foundations of Natural Law according to the Principles of the Doctrine of Science) that marriage is not simply a juridical society like the state; it is a natural and moral society as well.25 Hegel, however, goes much farther. The complex architectonics of the Grundlinien der Philosophie des Rechts (Elements of the Philosophy of Right) distinguishes the three levels of “abstraktes Recht” (“Abstract Right”), “Moralität” (“Morality”), and “Sittlichkeit” (“Ethical Life”).26

The crucial third part deals with the main social institutions of family, civil society, and state (the second one being a modern innovation compared with Aristotle).

The position of these institutions on the level of ethical life presupposes that they are not simply legal entities, that is, structures enforceable by legal mechanisms.They are, so to speak, composed of a legal part and a spirit that transcends abstract law because it appeals to an inner dimension that cannot be enforced. While in Kant morality is the inner dimension opposed to legality, Hegel insists that this inner dimension has to externalize itself too, albeit in a way that cannot be prescribed by law alone. This constitutes the “ethical” nature of all three social institutions. The difference between them is conceived in accordance with the general dialectical scheme of Hegel’s philosophy. Family is permeated by a strong altruistic feeling, which is both limited in its range and subjects the members of the family to considerable restrictions of their individuality. In civil society, a universal egoism that allows the satisfaction of particular needs through prudent behavior is dominant, although within important limits determined by the legal system. While the rejection of immediate altruism constitutes a loss, the expansion of the horizon is positive – it connects much more people, even beyond the borders of one’s own state. The state aims at a synthesis: It can only subsist if citizens have a commitment to the common good that transcends their individual interests; at the same time, the state is no longer built on emotional bonds within a small group, but on rational analysis.

The family is the ethical spirit as natural or immediate (306, § 157). Its basis is love, a unity of the spirit that feels itself. The self-consciousness of individuality subsists in this unity as a member, no longer as an independent person (307, § 158); thus, the category of right appears in it mainly in the stage of its dissolution (308, § 159). Hegel subdivides the family into marriage, care for common property, and the education of children. In the first step, the family is taken as an intersubjective unity; in the second, it relates to an exterior object; in the third, it creates new subjects. Note that not only Aristotle’s slaves but also Kant’s servants have disappeared; Hegel’s family is the nuclear one, ultimately a result of the Romantic revolution disliked by him. The central task of the marriage is the transformation of the natural sexual attraction into a self-conscious unit. The starting point is the free consent of two persons to form one person, that is, to limit the own personality in the new unit, which is at the same time a liberation. Therefore, marriage cannot be conceived as a contract, as Kant did in an ignominious way (157, § 75; 313 f; § 163).

With this position (which, however, does not entail a general indissolubility of marriage) Hegel breaks with the modern development characterized above as from sacrament to contract. While Hegel does not deny that the general decision to marry can be triggered by falling in love, according to him partners may also be chosen by parents, and he prefers a prior general resolution to marry to the marriage being merely a result of inclination, which is fleeting (310 f., § 162). Still, the ethical nature of marriage consists in the love and trust that underlie the common existence and the reduction of the sexual aspect to a mere moment, whose presence is not necessary for the validity of a marriage, which does not have a single defining end (313 ff., §§ 163 f.). However, Hegel insists on the necessity of a public expression of the commitment to each other, which constitutes the marriage and raises it above the transitory subjectivity of inclination. Three features of Hegel’s concept of marriage are crucial: first, the complementarity of the sexes (which in his eyes probably explains the exclusion of same-sex marriages), second, the monogamic nature of marriage (deduced from the totality of the commitment), third, the prohibition of marrying within the family of origin, which would deprive marriage of its being an act of freedom. Most problematic is Hegel’s doctrine of the complementarity of the sexes, since it is on its basis that he denies, for example, the inclusion of women in the workforce and their political rights. But it is correct that without this doctrine there are hardly any arguments against the exclusion of same-sex marriages, once one recognizes that reproduction is not the only legitimate purpose of marriage.

Based on his concept of the union of the persons, Hegel favors joint property of the spouses, even if he allows for reservations in the case of the dissolution of the marriage through death or divorce (323 ff., §§ 170 ff.). Analogously, he strongly supports limitations of testamentary freedom, for example in form of the legitime. For the marriage ideally continues in the children, in whom the unity of the marriage becomes as it were an object, in which the parents behold their own love (325 f., § 173). As in Kant, and unlike in Roman law, children have the right to be fed and raised; they are not their parents’ property. On the one hand, children should experience the ground of ethical life, love, trust, and obedience; on the other hand, they must be prepared for life in civil society and raised above their merely childish level (327 f., § 175). They have to leave the family – this is its ethical dissolution. Its natural one is the death of the spouses, its unnatural one their divorce, which Hegel acknowledges as an institution, even if it can only be decreed by a court (329, § 176).


Even the increasing insistence on symmetry between spouses in the new contractualist model did not yet lead to equal rights for women in the economic and political sphere. It is Fichte’s merit to have realized as one of the first thinkers that this inequality needed a justification, particularly since he shares Kant’s commitment to a universalist ethics based on equal freedom and sees in action the essence of self-consciousness. That women must have all the human and civil rights of men can only be gainsaid if they are denied their humanity – this is a principle that Fichte explicitly endorses (§ 33, III 344), and he obviously does not reject the humanity of women. Nevertheless, he claims that they cannot want to exert their rights. When unmarried, they are, like young men, under the authority of their fathers; and when married they have their dignity in being subjected to their husbands. Why? Fichte’s argument is based on the fact that women’s sexuality is passive and not active like the male one. This is incompatible with the active nature of self-consciousness, and a woman can only tolerate this humiliating contrast if she lives her sexuality in the form of a complete dedication to her husband. While a man can proudly satisfy his sexuality, a woman must be ashamed of it if she does not accept her husband with complete love (§ 3, III 306 f.). And this means that she cannot, for example, have any political rights but only try to influence her husband. I will not comment on these claims and ignore Fichte’s horrific denial of children having any rights by natural law, even the right to sustenance, with regard to their parents (§ 48, III 361 f.). What is progressive is something else. Based on his principle of the equal rights of the sexes and his theory that the married woman cannot want to claim them, Fichte recognizes that one must not deprive single women – whether unmarried, widowed, or divorced – of the economic and political rights that men have. However, since they cannot renounce the desire to marry (again) in the future, they cannot become public officials, for the future possible submission to their husbands would disqualify them from public duties.27 And since higher education should prepare for public work, women should not be allowed to access it (§§ 36 ff., 348 ff.). One sees that Fichte’s solution is very far from our modern sensibilities; but he has the merit to have raised the question more clearly than almost all of his male contemporaries.

The fight for the same economic and political rights for women is certainly one of the most important struggles of the 19th century. It was completed only in the 20th century in some – by far not all – countries of the world. It deeply impacted the nature of family, for in the moment in which the woman became economically independent, divorce became more feasible and the state had less interest in preventing it. Greater equality, even if not strictly incompatible with it, furthermore corroded the doctrine of the complementarity of the sexes. Perhaps the two most original works that pressed for legal equality are Mary Wollstonecraft’s A Vindication of the Rights ofWoman of 1792 and John Stuart Mill’s The Subjection of Women of 1869.28

Wollstonecraft’s monograph, dedicated to the former bishop Charles Maurice Talleyrand, is a foundational work in the history of feminism for at least two reasons. First, it is a woman herself who addresses the question. Before her, the matter was usually left to the deliberations of men. Second,Wollstonecraft’s touching demand for female rights is inspired by a deep and sincere religiosity and a strong sense of both justice and the moral duties of women. While raised as an Anglican, her religion in this phase of life is close to that of the Unitarian Rational Dissenters, also due to her friendship with Richard Price. Her rationalist, anti-voluntarist understanding of God, her rejection of a literal interpretation of the Bible, her claim that ethics is grounded in reason and not in sentiments, her belief in historical progress (19) are surprisingly similar to Kant’s, even if she did not know him and was ignored by him too: She did not read German, nor Kant English. Wollstonecraft upholds as her central idea the moral and legal equality of both sexes (thereby creating one strand of feminist philosophy, quite distinct from the other one that focuses on their radical difference). Again and again, Wollstonecraft maintains as strenuously that there is only one standard of virtue as that there is a God (31) and that one must not give “a sex to morals” (41). And her ultimate aim is to enable women to come as close as possible to the virtues traditionally associated with men and to gain respect even if she knows that society does not love masculine women (39). She detests features often connected with women, such as cunning, coquettishness, and the inability to control one’s passions and aims at reforming the world by reforming women (51).

But despite her hatred of this female degradation, she is convinced that it inevitably results from social structures that open only one avenue for the rise of women: marriage.This means that women are “legally prostituted” by their families (66) and taught to please and thus exert power over men, while it would be preferable if they learnt to have power over themselves. The root of this deportment is the false doctrine of the complementarity of the sexes, so powerful in Rousseau’s Emile: “Man was made to reason, woman to feel: and that together, flesh and spirit, they make the most perfect whole” (69). Women must get a chance to become intelligent and transcend the mere love for men (75). While at least Europe rejects polygamy, men who seduce and impregnate women do not have to fear legal sanctions, and while the unfortunate women and children may meet some charity, it is justice that is wanting (79). “The two sexes mutually corrupt and improve each other” (153). In order to have self-respect and gain “emancipation” (194), women must be allowed to gain their own subsistence and thus independence (94). Women’s characters are a result of early association of ideas in their minds, and the inequality in the treatment of the sexes explains why they are so obsessed with modesty or better, a show of modesty, as their main virtue. Wollstonecraft’s book also contains a sharp attack against social and political injustices, such as the slave-trade and wars that are not defensive (158 f.), and it is in this context that she demands comprehensive legal reforms concerning women.29 They must own property independently of their husbands and even have political representation, they must be allowed to study, for example, medicine (160 ff.), and the state must offer national public education besides, while not excluding private educational institutions. In both types of schools, coeducation of the sexes and the different classes should prevail (182 ff.). “For rights and duties are inseparable” (215).

What are the most important innovations in John Stuart Mill’s similar approach to the question? First, his methodological reflection on whether there are natural differences between the sexes is remarkably subtle. Mill considers “the nature of women ... an eminently artificial thing”, since it is partially the result of repression and stimulation (238), and declares the question of what are the unalterable traits of women unanswerable in the present state of society: “Those only could be inferred to be natural which could not possibly be artificial” (240). We will only be able to answer this question when we will have changed the educational and the legal system as a whole in its connection to women. Mill describes the British laws of his time as almost enslaving women, even if their consequences are tempered by the chivalric tradition. “We have had the morality of submission, and the morality of chivalry and generosity; the time is now come for the morality of justice” (259). And justice will not permeate society at large if it is not lived within the family (261). Servitude in marriage is an archaic remnant, contradicting all the principles of the modern world (295). But not only justice, the common good also demands that women be granted the same right as men, both in civil and in public law (268, 296). The economy will flourish if women are integrated into the workforce; and the number of qualified politicians can only increase if women are allowed to run for office too. Mill hopes, for example, that women in politics will diminish violence (300). And marriages will become both more stable and happier if the spouses have enjoyed a similar education (307 ff.).


Gustav Radbruch’s classic philosophy of law, one of the few composed in the 20th century, no longer tries to offer an answer to the traditional questions concerning property, contract, marriage, inheritance, punishment etc. Instead, it limits itself to describing different stances by which these problems could be approached, inevitably with very different results. The two main stances are the individualist and the supra-individualist one (sometimes supplemented by a third one, the transpersonal). In the case of marriage, the supra-individualist position is represented in paradigmatic way by the Catholic Church, the individualist in its most radical form by Soviet law.30 Radbruch ultimately does not believe that there are rational arguments for choosing one or the other but he recognizes that social changes drive marriage more and more in an individualistic direction.The traditional domestic community in an own house with garden, dedicated to the satisfaction of most economic needs by the activities of the various family members, has been replaced in capitalism by disconnected jobs that family members practice in very different economic sectors, without any connection to each other, often living in condos door to door with neighbors that remain alien to them. But of course, one may argue that just because of these social forces that endanger traditional marriage a spiritual justification of the institution is even more necessary than before.

What can our time learn from the four most important theories of the family, which stood in the focus of this essay? I think, first, that Aristotle’s critique of Plato has convincingly shown that the replacement of the family by the state is an absurd and nightmarish ideal. While Plato is right that a spirit of tribalism may prevent the emergence of a public consciousness, the abrogation of the family will certainly not increase universal altruism but eradicate altruism already in its beginning. A complex society needs more than the love that holds family members together, but this more must grow out of it, as Hegel very well understood. Against Hegel, however, I would claim that we also need more than responsibility for our own state and have to learn to develop a “public sense” for the whole planet, a planetary consciousness supported by the cooperation of the universal religions.

Second, against both Plato and Aristotle we have to recognize the inalienable individual rights that children have, and that must have consequences for the legal regulation of reproduction.They are not the property of their parents, nor a tool for the demographic ambitions of the state. When parents do not fulfill their duties or even violate children’s welfare, the state must step in. It is the merit of Kant and Hegel to have elaborated this point, which was alien to antiquity, which did not yet recognize universal individual rights. For these became the basis concept of modern natural law only in a slow process starting with the Late Spanish Scholastics.

Hegel is also right that, third, among the many features of a successful marriage the crucial one is the commitment to a common life with shared responsibilities for each other. The obsession with the sexual act so characteristic of Kant is eliminated in Hegel’s grand philosophy of the social institutions as manifestations of the freedom of the spirit. Probably the weakest part of his theory is, however, the doctrine of the complementarity of the sexes – at least as long as it is not disconnected from the traditional understanding that the ideal realm for women is the household, while civil society and the state are the arenas of men.

For there is, fourth, little doubt that the crisis of the nuclear family that we have witnessed since at least the second half of the 20th century in the Western world is driven, not only, but to a considerable part, by the utterly legitimate desire of women to be on a par with men. Paradoxically, of the four greatest philosophers the one most understanding of the female desire for an education comparable to that of men was our first, Plato. Will it be possible to unite Plato’s (and Wollstonecraft’s and Mill’s) sensitivity to the intellectual needs of women with Aristotle’s and Hegel’s recognition of the necessity of various levels of social institutions and corresponding moral attitudes as well as with Kant’s commitment to equal rights for everybody? In all likelihood, the future of the family depends on a positive answer to this question. 


1 See my analysis in: Morals and Politics, Notre Dame 1997, 197 ff. The book also offers my own systematic ideas on the family (693 ff.).
2 In his important macro-sociological study, Family and Civilization (New York 1947), Carle C. Zimmermann coined the terms of trustee, domestic, and atomistic family, describing families with maximum strength, middle strength, and maximum weakness. The trustee family considers individuals, and even nuclear families, as nothing more than trustees and vehicles of a structure that surpasses individual generations and is potentially eternal. 
3 A good overview of the legal and philosophical controversies concerning modern families can be found in: Laurence D. Houlgate, Family and State. The Philosophy of Family Law, Totowa 1988. 
4 “The Private and the Public in the Republic and in the Analects”, in: Confucius and Cicero, ed. Andrea Balbo/Jaewon Ahn, Berlin/Boston 2019, 29-42, 39. 
5 Punishments for bachelors after a certain age were customary in Sparta, whose idealized institutions inspire much of what Plato recommends. See W.K. Lacey, The Family in Classical Greece, Ithaca 1968, 177 ff., esp. 197. 
6 Think of art. 559 of the Italian Codice Penale, which was declared unconstitutional only in 1968 and 1969. It limited the legal concept of adultery to the woman; the husband could only be punished if he held a concubine in the house of the spouses or “notoriously” somewhere else (art. 560). This cavalier attitude toward male adultery can be found, for example, in the 18th century in such an explicitly Christian author as Samuel Johnson: “I would not receive home a daughter who had run away from her husband on that account. ... a man will not, once in a hundred instances, leave his wife and go to a harlot, if his wife has not been negligent of pleasing” (James Boswell, Life of Johnson, Oxford/New York 1998, 394). David Hume also defends the double standard (Treatise of Human Nature, Book III, Part II, Section 12), and, of course, so does Louis de Bonald, Du divorce, considéré au XIXe siècle, relativement à l’état domestique et à l’état publique de société, Paris 3rd ed. 1818, 307 f. On the other hand, in antiquity, in addition to Plato, the Stoics Musonius Rufus (Discourses 12) and Seneca (Epistles to Lucilius 94.26) rejected it.
7 Family and the question of women in the Laws, in: Plato’s Laws. A Critical Guide, ed. Christopher Bobonich, Cambridge 2010, 172-196, 196. 
8 Cfr. Aristoteles, Politik, Buch 1, ... ūbersetzt und erläutert von Eckart Schtrumpf, Darmstadt 1991, 200.
9 For a balanced view, see Devin Henry, “How Sexist Is Aristotle’s Developmental Biology?”, in: Phronesis 52 (2007), 251-269. 
10 See, concerning chastity, Mt 19:10 ff. and 1 Cor 7.
11 De nuptiis et concupiscentia (On Marriage and Concupiscence) I 10.11.
12 The slowness of the social and, even more, the legal changes demanded by the Christian doctrine is convincingly demonstrated by Geoffrey Nathan, The Family in Late Antiquity. The rise of Christianity and the Endurance of Tradition, London/New York 2000. He rightly points out as a limit of the Christian doctrine that it did not extend “its notions of husband-wife equality past the realm of fidelity” (186). 
13 I include exposure under infanticide since the fate of exposed children was not always but very often death (see Judith Evans Grubbs, Infant Exposure and Infanticide, in: The Oxford Handbook of Childhood and Education in the Classical World, ed. Judith Evans Parks/Tim Parkin/Rosalynne Bell, Oxford 2013, 83-107). This does not mean that there were not pagan critics of the institution. I mention Musonius Rufus, Discourses XV and XV a, who in fact is quoted by the Fathers.
14 De civitate Dei (City of God) XV 16. It has been recently argued that one of the reasons for the peculiar success of Western cultures was the Catholic Church’s strict taboo on marriages between even quite distant relatives; for it prevented the formation of family clans, which have rendered the formation of a meritocratic society and polity so difficult for example in the Arab world. See Joseph Henry, The WEIRDest people in the world: how the West became psychologically peculiar and particularly prosperous, New York 2020, 193 ff.
15 The doctrine of these three goods of marriage still inspires the Encyclical of Pope Pius XI Casti connubii of 1930. 
16 On this process see the excellent study by John Witte Jr., From Sacrament to Contract. Marriage, Religion, and Law in the Western tradition, Louisville 2nd ed. 2012, especially 113 ff. I owe much to this book.
17 John Milton, The Divorce Tracts, ed. Sara J. van den Berg/W. Scott Howard, Pittsburgh 2010, 44.
18 Summa theologica, Supp. q. 58 a. 1 ad 4. 
19 Thomas Hobbes, too, rejects the idea that the paternal power is derived from the generation of the children as such; the children’s consent, although not necessarily explicit, is needed, and they will give it to those who protect them. Since there are two parents, in the state of nature it depends on their agreement who will have the dominion over the children; if the parents do not agree it is naturally with the mother, for without matrimonial laws only she knows who the father is (Leviathan, ed. C.B. Macpherson, London/Harmondsworth 1981, Ch. 20, 253 f.). Hobbes’s rejection of a natural basis of family evidently is connected to his rejection of a natural sociability of humans and his reduction of social relations to contracts based on fear. See Justine Roulin, Autorité, sociabilité et passions. La philosophie de la famille de Thomas Hobbes à John Millar, Basel 2022, 107 f.
20 John Locke, Two Treatises of Government, ed. Peter Laslett, Cambridge 1967, 321. 
21 Essays Moral, Political, and Literary, ed. Eugene F. Miller, Indianapolis 1987, 185.
22 Wilhelm von Humboldt, Werke, ed. Albert Leitzmann, Vol. 1: 1785-1795, Berlin 1903, 119-122. 
23 I quote according to Immanuel Kant, WerkausgabeVIII: Die Metaphysik der Sitten, hg. vonW.Weischedel, Frankfurt 1979 but give the original pagination of the first two editions. 
24 This is rightly stressed in an intelligent defense of crucial parts of Kant’s theory by Allan Beever, Kant on the Law of Marriage, in: Kantian Review 18 (2013), 339-362, 340: Despite his use of terms from Roman law, Kant challenges “received notions by portraying the relevant relationships as ones of equality and interdependence rather than domination under a paterfamilias or dominant male”. 
25 Cfr. Fichtes Werke, hg. von Immanuel Hermann Fichte, Reprint Berlin 1971, III 304.
26 I quote the work according to: Georg Wilhelm Friedrich Hegel, Werke 7: Grundlinien der Philosophie des Rechts oder Naturrecht und Staatswissenschaft im Grundrisse, Frankfurt 1979, but give after the page number the paragraph number so that the passages may be found also in other editions and in translations as well. 
27 In Germany, female teachers who were public officials could be dismissed until after the SecondWorldWar if they married (Deutsches Beamtengesetz § 63). 
28 I quote both books according to: Mary Wollstonecraft, A Vindication of the Rights of Woman/John Stuart Mill, The Subjection of Women, London/Rutland 1985. 
29 See Eileen Hunt Botting, Family Feuds: Wollstonecraft, Burke, and Rousseau on the Transformation of the Family, Albany 2006, 131 f.: “her understanding of patriarchy encompassed all the sex-based and class-based hierarchies that perpetuated the male dominated social order”. 
30 Gustav Radbruch, Rechtsphilosophie, ed. Erik Wolf/Hans-Peter Schneider, Stuttgart 8th ed. 1973, 244 ff.