Sources and References

Primary sources — Immanuel Kant, Groundwork of the Metaphysics of Morals and Lectures on Ethics; Martha Nussbaum, “Objectification” (Philosophy and Public Affairs, 1995) and Sex and Social Justice (1999); Rae Langton, Sexual Solipsism: Philosophical Essays on Pornography and Objectification (2009); Catharine MacKinnon, Feminism Unmodified (1987) and Only Words (1993); Alan Soble (ed.), The Philosophy of Sex (anthology, multiple editions); Roger Scruton, Sexual Desire: A Philosophical Investigation (1986); Robert Nozick, “Love’s Bond,” in The Examined Life (1989); Robert Solomon, “The Virtue of Love” (Midwest Studies in Philosophy, 1988); Harry Frankfurt, Reasons of Love (2004) and The Importance of What We Care About (1988); J. David Velleman, “Love as a Moral Emotion” (Ethics, 1999); Elizabeth Brake, Minimizing Marriage: Marriage, Morality, and the Law (2012); Carrie Jenkins, What Love Is and What It Could Be (2017); Alan Wertheimer, Consent to Sexual Relations (2003); Robin West, “Consent, Rape, and the Meaning of Sex” (Georgetown Law Journal, 2000); John Corvino, What’s Wrong with Homosexuality? (2013); Sally Haslanger, Resisting Reality: Social Construction and Social Critique (2012); David Benatar, Better Never to Have Been (2006) and “The Ethics of Procreation” essays.

Online resources — Stanford Encyclopedia of Philosophy entries: “Feminist Perspectives on Sex and Gender”; “Pornography and Censorship”; “Philosophy of Love”; “Sexual Orientation”; “Marriage and Domestic Partnership”; “Polyamory”; “Consent”; Internet Encyclopedia of Philosophy entries: “Philosophy of Sex”; “Objectification.”

Chapter 1: Desire and Lust — Philosophical Perspectives

1.1 What Is Sexual Desire?

Human sexuality has long puzzled philosophers. Unlike hunger or thirst — bodily appetites that admit relatively straightforward biological description — sexual desire (性欲) seems to occupy a peculiar intersection of the physical and the interpersonal. Roger Scruton, in Sexual Desire, argues that what distinguishes sexual desire from mere appetite is its essentially intentional character: we do not simply want sex in the abstract; we desire a particular person, and that desire is laden with the specific ways we understand, interpret, and project onto them.

This intentionality distinguishes sexuality from mere bodily urgency. Scruton draws on phenomenological traditions to suggest that sexual desire is always desire for someone understood as a subject — someone who can reciprocate, refuse, and be harmed by our attention. In this respect, sexual desire already carries an implicit moral grammar within it: to desire someone sexually is to enter into a relationship that is, from the outset, ethically charged.

1.1.1 The Role of the Body

Philosophers of mind have debated how embodiment shapes sexual experience. Thomas Nagel’s classic 1969 paper “Sexual Perversion” offers an influential analysis: genuine sexual desire involves a complex structure of mutual awareness. When A desires B, A is aware of B; but Nagel insists that what is distinctively sexual is when A is aware that B is aware of A’s desire, and B in turn is aware of A’s awareness, generating a spiral of mutual recognition. On this view, sexual desire is not raw biological drive but an interpersonal phenomenon that requires and seeks acknowledgment.

1.1.2 Lust and Its Moral Valence

Lust (色欲) is the traditional theological and philosophical category for sexual desire that has been cut loose from its appropriate relational context. In much of Western moral theology (Augustine, Aquinas), lust is a vice precisely because it treats the other as an instrument of pleasure rather than a person deserving respect. The Kantian tradition — which we will explore extensively in Chapter 2 — inherits this concern, though it reformulates it in secular terms.

Yet some contemporary philosophers push back against the blanket condemnation of lust. Alan Goldman’s “Plain Sex” (1977) argues that sexual desire is simply the desire for contact with another’s body, and that this is not inherently wrong or degraded. Goldman is a deflationary naturalist: he resists what he calls “means-end analyses” that require sex to be justified by reference to love, reproduction, or spiritual union. Plain sex, he contends, can be valued for its own sake without moral apology.

1.2 Philosophy of Desire: Broader Frameworks

1.2.1 Plato’s Eros

The Western philosophical tradition begins its discussion of sexual desire with Plato. In the Symposium, several speakers offer accounts of eros (愛慾): from Aristophanes’ myth of the split beings who seek their other halves, to Socrates’ transmission of Diotima’s ladder, which ascends from love of beautiful bodies through love of beautiful souls to the Form of Beauty itself. For Plato, eros is a fundamentally upward-moving force: it starts in the body but ought to carry the soul toward transcendence.

This framework has had enormous influence, but it also contains a troubling implication: the body and particular persons become mere rungs on a ladder to be discarded. Later critics — including Martha Nussbaum in The Fragility of Goodness — have argued that the Platonic conception systematically devalues particularity and the fragile attachments that constitute human love.

1.2.2 Aristotelian Desire and the Good Life

Aristotle’s account of desire situates it within his broader eudaimonic ethics. Desires are appropriate or inappropriate depending on whether they are integrated into a life of eudaimonia (幸福/圓滿). Unlike Plato, Aristotle does not seek to transcend the body; instead, he holds that virtuous persons will experience the right desires at the right times, toward the right objects, in the right measure. Sexual desire, for Aristotle, is not inherently problematic — only its excess or misdirection is.

1.2.3 Freudian and Post-Freudian Views

Sigmund Freud’s theorization of the libido introduced the idea that sexual desire is a pervasive, polymorphous force that undergoes development, repression, and sublimation. While Freud’s specific claims are not the province of philosophy, his framework influenced philosophers significantly: Herbert Marcuse’s Eros and Civilization (1955) reads the repression of eros as central to capitalist social organization, arguing that a liberated sexuality could ground a more emancipatory social order.

Chapter 2: Sexual Objectification

2.1 The Concept of Objectification

Objectification (物化) is the treatment of a person as an object — a thing lacking the subjectivity, autonomy, and dignity that persons possess. While the intuition that objectification is wrong is widely shared, articulating precisely what objectification consists in, and why it is wrong, requires careful philosophical work.

Martha Nussbaum’s landmark 1995 paper “Objectification” provides the most detailed taxonomy of the concept in the contemporary literature. Nussbaum identifies seven distinct properties that can characterize objectifying treatment:

2.1.1 Nussbaum’s Contextual Approach

A distinctive and controversial feature of Nussbaum’s account is her insistence that objectification is not always wrong. She offers the example of a loving sexual relationship in which one partner treats the other’s body in a somewhat objectifying way — focusing on physical pleasure, temporarily treating the partner as an instrument of enjoyment — while the broader relational context of mutual respect and care remains intact. In such cases, Nussbaum argues, objectification may be benign or even valuable.

This contextual approach has been criticized by more categorical feminists who worry that it provides too easy an excuse for harmful treatment. But Nussbaum’s point is subtle: what makes objectification wrong is not any single feature in isolation but a failure of the broader context to honor the other’s full personhood.

2.1.2 Langton’s Extensions: Autonomy-Denial and Instrumentality

Rae Langton, in Sexual Solipsism, extends Nussbaum’s analysis by adding two further features: silencing (沉默化) and reduction to appearance (以外貌簡化). Silencing involves treating someone as incapable of performing certain speech acts — their refusals are not registered as genuine refusals, their protests not received as meaningful objections. Reduction to appearance involves treating someone as though their entire significance lies in how they look.

Langton’s addition of silencing is philosophically significant because it connects objectification theory to speech-act theory. Objectification, on this expanded view, is not only a matter of what we do to bodies but of what we do to communicative agency.

2.2 The Kantian Foundation

2.2.1 The Formula of Humanity

The Kantian critique of objectification is grounded in the Formula of Humanity (人性公式), one of Kant’s formulations of the Categorical Imperative: “Act so that you treat humanity, whether in your own person or in that of another, always as an end and never as a means only” (Groundwork, 4:429).

The formula does not prohibit using other persons as means — such use is unavoidable in everyday social life — but it prohibits treating them merely as means, that is, in ways that fail to honor their status as rational agents capable of setting their own ends. Sexual objectification, on a Kantian analysis, is paradigmatically wrong when it reduces a person to an instrument of one’s pleasure while ignoring or suppressing their rational agency.

2.2.2 Rational Agency and Sexual Ethics

Kant’s framework raises a deep question: is it possible for sexual relations to fully honor the rational agency of the other? Scruton thinks something like this is possible through the cultivation of erotic personhood — a mature sexuality in which desire is responsive to the other as a person rather than merely a body. Feminist theorists like Nussbaum are more cautious: given structural inequalities of gender, race, and class, the conditions for genuinely respectful sexuality are rarely fully met and must be fought for politically, not merely cultivated privately.

2.3 Self-Objectification

A further dimension of objectification theory concerns the phenomenon of self-objectification (自我物化). Feminist psychologists Barbara Fredrickson and Tomi-Ann Roberts have argued that when women are chronically objectified, they internalize an observer’s perspective on their own bodies, monitoring their appearance rather than experiencing embodied activity. Philosophers like Sandra Bartky have explored how this constitutes a form of alienation — estrangement from one’s own bodily experience and agency.

Chapter 3: Pornography — Feminist Debates

3.1 The Feminist Critique of Pornography

3.1.1 MacKinnon’s Argument

Catharine MacKinnon offers the most influential radical feminist critique of pornography. For MacKinnon, pornography is not primarily a representation but a practice (實踐): it is a mechanism by which male supremacy is constructed, maintained, and normalized. In Feminism Unmodified and Only Words, she argues that pornography does not merely depict the subordination of women — it enacts and constitutes that subordination.

MacKinnon’s argument has both a descriptive and a normative dimension. Descriptively, she argues that the pornography industry is suffused with coercion — women are often filmed under conditions of duress, economic desperation, or outright physical threat. Normatively, she argues that even where individual women appear to consent, pornography as a social institution perpetuates a system in which women’s sexuality is systematically defined by and for male pleasure.

3.1.2 The Ordinance Approach

MacKinnon, together with Andrea Dworkin, drafted the Minneapolis and Indianapolis antipornography ordinances (1983–84), which defined pornography as a civil rights violation. These ordinances would have allowed women harmed by pornography — whether through its production or through its use against them — to seek civil damages. While ultimately struck down as unconstitutional violations of the First Amendment, the ordinances represent an important attempt to use legal mechanisms to address feminist concerns about pornography.

3.2 Langton’s Speech-Act Framework

3.2.1 Illocutionary Acts and Silencing

Rae Langton deploys J.L. Austin’s speech-act theory to offer a philosophically sophisticated defense of a version of MacKinnon’s argument. For Austin, utterances are not merely vehicles for propositional content (locutionary acts); they also perform social actions (illocutionary acts), such as promising, warning, or asserting. An illocutionary act succeeds only if the speaker has the appropriate authority and the audience appropriately uptakes the act.

Langton argues that pornography functions as an illocutionary act (以言行事) that ranks women as inferior, legitimates their sexual subordination, and — crucially — silences them. The silencing occurs because pornography shapes the social conditions under which women’s speech acts are received. When pornography teaches that women’s “no” means “yes,” it produces an environment in which women’s refusals of sexual advances lack illocutionary force: they are not registered as genuine refusals.

3.2.2 Critiques of the Speech-Act Argument

The speech-act argument has attracted significant philosophical attention and criticism. Jennifer Hornsby and Langton respond to objections about causation — how exactly does pornography cause silencing? — by appeal to the concept of uptake: what pornography does is shape the background conditions that determine whether certain speech acts receive appropriate uptake. Critics like Ronald Dworkin (not to be confused with Andrea Dworkin) argue that this framework threatens free expression by allowing the silencing of pornography in the name of protecting women’s speech.

3.3 Liberal and Pro-Sex Feminist Responses

Not all feminist theorists support restrictions on pornography. Liberal feminism (自由主義女性主義) emphasizes individual autonomy: if women freely choose to participate in pornography, prohibiting or restricting it is paternalistic. Ellen Willis and Gayle Rubin argue that the antipornography position is complicit with conservative sexual politics that has historically been used against queer sexuality and women’s own erotic expression.

Nadine Strossen’s Defending Pornography (1995) argues that the harms attributed to pornography are exaggerated and that censorship causes more harm than the material it targets. On this view, the proper feminist response to objectifying pornography is not restriction but counter-speech: the production and circulation of alternative, egalitarian representations of sexuality.

Chapter 4: Consent and Sexual Ethics

4.1 The Centrality of Consent

Consent (同意) is widely regarded as the cornerstone of sexual ethics in liberal democratic societies. The thought is simple and compelling: what distinguishes rape from sex is consent; what distinguishes prostitution from sexual assault is consent; what distinguishes BDSM from torture is consent. Consent is the moral membrane that separates legitimate from illegitimate sexual activity.

Yet despite — or perhaps because of — this central role, consent turns out to be philosophically complex. What is consent? What conditions must be met for consent to be valid? Can consent be coerced? What is the relation between consent and harm?

4.2 Wertheimer’s Analysis

Alan Wertheimer’s Consent to Sexual Relations provides the most systematic contemporary philosophical analysis of consent in the sexual domain. Wertheimer distinguishes between:

Wertheimer argues for a generally liberal position: consent transforms, and we should be cautious about invalidating consent on grounds of imperfect conditions, lest we undermine autonomy by treating adults as unable to make meaningful choices under non-ideal circumstances.

4.2.1 Valid Consent Conditions

For consent to be morally transformative, several conditions are typically required:

• Competence: the consenting party must be capable of understanding and reasoning about the relevant choice.
• Information: the consenting party must have adequate information about what they are consenting to.
• Voluntariness: the consent must not be the product of coercion, deception, or manipulation.
• Expression: the consent must be communicated in some recognizable way (verbally, non-verbally, or through established context).

4.3 West’s Feminist Critique of Consent

Robin West argues that the liberal consent framework, while formally correct, is substantively inadequate as a basis for sexual ethics. Her argument has several strands:

First, West points out that even fully consensual sex can be harmful to women. If a woman consents to sex she finds meaningless, degrading, or physically painful because she fears her partner’s displeasure, her consent is formally valid but the sex is not thereby morally unproblematic. The consent framework, West argues, is systematically blind to this category of harm.

Second, West argues that the category of rape (強姦) as legally and philosophically defined captures only the extreme end of a spectrum of harmful, unwanted sexual experiences. Much sexual harm — the “gray zone” of unwanted but technically consensual sex — falls through the gaps of a purely consent-based framework.

4.3.1 Date Rape and Affirmative Consent

The concept of date rape (約會強姦) — sexual assault by an acquaintance or romantic partner — raises distinct philosophical issues. Traditional legal definitions of rape focused on force; feminist reformers successfully argued that nonconsent, not force, should be the central criterion. More recent debates concern affirmative consent (積極同意): the requirement that consent be explicitly communicated at each stage of sexual activity, rather than assumed from silence or passivity.

Affirmative consent standards have been adopted by many universities and some jurisdictions. Defenders argue they better protect against assault and more accurately reflect what genuine consent requires. Critics argue they are unworkable in practice, or that they are so demanding as to criminalize ordinary sexual communication.

Chapter 5: Sex Work — Autonomy, Exploitation, and Well-Being

5.1 Framing the Question

Sex work (性工作) is among the most contested topics in applied ethics. The term itself is contested: some prefer “prostitution” to emphasize what they see as inherently exploitative relations; others prefer “sex work” to recognize agency and foreground labor conditions. We use “sex work” throughout, while recognizing that the choice of terminology is not neutral.

The central philosophical questions are: (1) Is sex work inherently degrading or exploitative, or can it be a legitimate occupation? (2) What are the implications for law and policy — criminalization, decriminalization, legalization, or the Nordic model? (3) What is the relationship between sex work and gender inequality?

5.2 The Exploitation Thesis

One influential view holds that sex work is inherently exploitative, even when apparently consensual. The argument runs as follows: sex workers are overwhelmingly driven to their work by economic necessity; the choice to engage in sex work is therefore not fully free but constrained by poverty and lack of alternatives. Consent given under such conditions does not have the moral weight of genuine autonomous consent.

Furthermore, critics argue, sex work is structurally embedded in patriarchal systems that define women’s sexuality as a commodity for male consumption. Even where individual transactions are consensual, participation in sex work reinforces this system.

Carole Pateman’s The Sexual Contract (1988) argues that prostitution involves a distinctive form of domination: when a man buys sexual services, he does not merely hire labor but exercises a form of command over the person (對人的支配) that is inconsistent with equal citizenship.

5.3 Autonomy-Based and Harm-Reduction Views

Martha Nussbaum has offered a philosophically sophisticated version of this argument. In “Whether from Reason or Prejudice: Taking Money for Bodily Services,” she argues that many occupations involve selling the use of one’s body under conditions of stigma and unequal power — coal mining, domestic service, opera singing — and asks why sex work is thought to be uniquely problematic. Her answer is that much of the stigma attached to sex work is a product of unjustified moral squeamishness about sexuality rather than genuine harm analysis.

5.4 Well-Being and Empirical Realities

A philosophically responsible account of sex work must engage with empirical evidence about its effects on well-being. This evidence is complex and contested:

• Some studies document high rates of trauma, violence, and PTSD among street-based sex workers, particularly in criminalized environments.
• Other studies document sex workers — particularly those working in safer, indoor environments — who report comparable or better well-being than in previous occupations.
• Research on trafficking complicates consent-based frameworks, since a significant proportion of global sex work occurs under conditions of coercion.

Chapter 6: Sexual Orientation and Gender Identity

6.1 Philosophical Questions about Orientation

Sexual orientation (性取向) designates the direction of an individual’s sexual attraction — toward persons of the same sex (homosexuality 同性戀), the opposite sex (heterosexuality 異性戀), both (bisexuality 雙性戀), neither (asexuality 無性戀), or various other configurations. Philosophical questions include: What is the nature of orientation — biological, social, or some combination? Is it a stable feature of identity? And what are the implications for ethics and politics?

6.1.1 Essentialism vs. Constructionism

The debate between essentialism (本質主義) and social constructionism (社會建構主義) about sexual orientation is one of the central conceptual disputes in this area. Essentialists hold that sexual orientations are natural kinds — real features of human beings that exist independently of social categories and vary across cultures. Constructionists hold that the concept of “sexual orientation” as a stable property of persons is a relatively recent historical invention, and that the phenomena it picks out are differently configured in different social and historical contexts.

Michel Foucault’s The History of Sexuality (1976) is the locus classicus of the constructionist view. Foucault argues that the “homosexual” as a type of person — someone defined by their sexuality — is a nineteenth-century invention. Before that, there were acts (sodomy) but not identities. This historical claim has been influential in queer theory.

6.2 Corvino’s Defense of Homosexuality

John Corvino’s What’s Wrong with Homosexuality? systematically examines and refutes the philosophical arguments offered against homosexuality. These arguments fall into several categories:

6.3 Gender Identity and Philosophy

Gender identity (性別認同) — one’s inner sense of one’s own gender — raises distinct philosophical questions from sexual orientation. Sally Haslanger’s influential work distinguishes between:

• Sex (生理性別): biologically defined categories, typically on the basis of chromosomes, hormones, and anatomy.
• Gender (社會性別): socially constructed categories that organize social roles, norms, and expectations.

Haslanger argues for an ameliorative approach: rather than asking what gender “really is” in some metaphysically fundamental sense, we should ask what concept of gender best serves the purposes of feminist critique and social justice. This approach yields a definition of women and men in terms of social position — the occupying of a certain hierarchical role — rather than in terms of biology or self-identification.

Trans philosophers and theorists have challenged aspects of this framework, arguing that Haslanger’s social-structural definition may not adequately capture the significance of gender identity as a felt, first-person phenomenon.

Chapter 7: Theories of Love I — Union and Merger Views

7.1 What Is Love?

The philosophy of love asks: What is love? What makes love rational or irrational? Is love a feeling, an emotion, a desire, an attitude, or a commitment? What are love’s characteristic objects? How does love relate to morality?

These questions resist easy answers partly because “love” covers enormously diverse phenomena: romantic love, parental love, friendship, love of humanity, love of God. Different philosophical traditions have emphasized different aspects. We begin with theories that emphasize union or merger.

7.2 Nozick’s Union Theory

Robert Nozick’s “Love’s Bond,” in The Examined Life, offers an elegant articulation of the union view (合一觀) of romantic love. On Nozick’s account, what romantic love essentially involves is the formation of a new entity — a “we” — out of two previously separate individuals.

7.2.1 Features of the Union

Nozick elaborates several features of this union:

• Pooled well-being: each partner’s flourishing and suffering affects the other not merely instrumentally but constitutively. If my partner thrives, that is partly my thriving; if they suffer, that is partly my suffering.
• Shared identity: lovers often speak using first-person plural (“we are going to Paris”) in contexts where mere coordination would not warrant it, reflecting a genuine experience of merged identity.
• Mutual vulnerability: because each has staked part of their identity on the relationship, each becomes vulnerable in ways they were not previously.

7.2.2 Critiques of the Union View

The union view has faced several important philosophical objections:

First, critics argue that the merger of selves is not only impossible but undesirable. If I literally merge my identity with my partner’s, what becomes of my independent selfhood, projects, and relationships? The concern is that union views romanticize a kind of self-dissolution that, in practice, often falls disproportionately on women in heterosexual relationships, who are expected to subordinate their identities to the couple’s shared identity.

Second, fungibility worries arise: if love constitutes a new “we,” why should it matter whether this “we” is formed with this particular person rather than another? Union views seem to struggle to account for the irreplaceability (不可取代性) of the beloved.

7.3 Solomon’s Shared Emotions View

Robert Solomon, in “The Virtue of Love” and other essays, develops a related but distinct union view that locates love in shared emotions (共同情感). For Solomon, love is not primarily a feeling toward the other but a way of being in the world jointly — a shared emotional life.

Solomon emphasizes that love involves a kind of emotional identification: when I love someone, their joys and sorrows are not merely occasions for sympathetic response in me but are directly mine. This is not empathy (understanding what another feels) but something more intimate: constitutive emotional sharing.

Chapter 8: Theories of Love II — Concern and Appraisal Views

8.1 Frankfurt’s Concern View

Harry Frankfurt’s Reasons of Love and The Importance of What We Care About develop a concern view (關愛觀) of love. For Frankfurt, love is not primarily a response to perceived qualities of the beloved but a structuring commitment: to love someone is to care about them — to make their well-being an end in itself, not merely as a means to anything else.

8.1.1 Love Without Reasons?

A striking and controversial feature of Frankfurt’s view is his claim that love is not, at its core, a response to reasons. We do not love people because of their qualities — if we did, anyone with equivalent qualities would be equally lovable, and love would be fungible and transferable. Instead, Frankfurt argues, love creates reasons: because I love my child, her interests give me reasons I would not otherwise have; the love comes first, the reasons follow.

This view aligns with the phenomenology of love — lovers typically experience their love as non-transferable even when they recognize that others might be equally virtuous or attractive. But it faces the challenge of explaining how love can be rational at all if it is not grounded in the beloved’s properties.

8.1.2 Autonomy and Love

Frankfurt also argues that love is central to autonomous selfhood (自主性). We are not mere bundles of preferences and desires; we are selves insofar as we care about certain things wholeheartedly and irreversibly. Love — of persons, projects, and ideals — constitutes the core of who we are, providing the standpoint from which we evaluate other desires and make choices.

8.2 Velleman’s Appraisal View

J. David Velleman’s “Love as a Moral Emotion” offers a contrasting account. For Velleman, love is a response to the Kantian value of the person (對人之康德式價值的回應): specifically, to the other’s status as a rational agent whose existence has unconditional worth. Love, on this view, is not concern for welfare but something more like moral respect elevated to an emotional register.

8.2.1 Love and Vulnerability

Velleman argues that love characteristically involves a kind of disarmament (解除防備): to love someone is to be made vulnerable to their reality — to be unable to shield oneself from their joy and suffering through the usual emotional defenses. This disarmament is not mere empathy but something more radical: the other’s reality presses on us in a way that cannot be managed at a distance.

8.2.2 Velleman vs. Frankfurt

The contrast between Velleman and Frankfurt is philosophically illuminating:

8.3 Jenkins and the Dual Nature Theory

Carrie Jenkins’s What Love Is and What It Could Be proposes a dual nature theory (雙重本質論) of romantic love. Love, Jenkins argues, has both a biological nature — rooted in evolved neural systems involving attachment, reward, and bonding — and a social nature — shaped by cultural norms, historical practices, and social institutions.

Neither nature is reducible to the other. The biological dimension explains why love has the phenomenological urgency and involuntary character it often does; the social dimension explains why love takes the particular forms it does in particular cultures, why romantic love as we know it is a historically specific phenomenon, and why alternative forms of love — including non-monogamous love — are genuinely possible.

Jenkins’s account has political implications: if romantic love has a social nature that is shaped by institutions, then transforming those institutions (including marriage and norms of monogamy) can transform what kinds of love are available to people.

Chapter 9: Love, Friendship, and Moral Life

9.1 Aristotle on Friendship and Its Varieties

Aristotle’s account of philia (友愛/愛) in the Nicomachean Ethics (Books VIII–IX) provides the starting point for philosophical discussion of friendship and love. Aristotle distinguishes three kinds of friendship based on their ground:

9.1.1 The Limits of Aristotelian Friendship

Aristotle’s account of virtue friendship has been criticized on several grounds. First, Aristotle appears to hold that full friendship requires similarity in virtue — we can only be friends with those who are, roughly, our equals in character. This raises questions about whether and how friendship is possible across significant differences of power, class, gender, or race.

Second, Aristotle’s conception of philia is broader than the English “friendship” and includes family bonds and civic relationships. Contemporary philosophers have asked whether the deep mutual concern characteristic of Aristotelian friendship is compatible with the wider impartiality demanded by morality.

9.2 Partiality and Impartiality

The moral life requires both particular attachments and general impartiality. We have special obligations to friends, family, and lovers that we do not have to strangers; yet morality also demands that we give equal weight to the interests of all. This generates a potential tension: can love and friendship survive the demand for impartiality?

Bernard Williams famously argued in “Persons, Character, and Morality” that demanding a man to give impartial justification for saving his drowning wife rather than a stranger is a demand “one thought too many.” The thought reveals a failure of genuine love: the man who loves his wife acts from that love directly, not from a calculation that love-based partiality is impartially justified.

9.3 Love and Moral Development

Some philosophers argue that love and friendship are not merely compatible with morality but are central to moral development. Nel Noddings’s ethics of care (關懷倫理學), developed in the tradition of feminist philosophy, holds that caring relationships — paradigmatically those between mothers and children — are the foundation of ethical life. Morality is not primarily a matter of adhering to universal principles but of maintaining and deepening relationships of care.

Nussbaum’s work similarly emphasizes that emotions — including love — are not mere noise in the moral signal but are themselves forms of moral perception. To love someone is to notice morally relevant features of their situation — their vulnerability, their specific needs, their particular history — that impartial calculation might miss.

Chapter 10: Promising to Love — Commitment and Fidelity

10.1 Can Love Be Promised?

Marriage and committed partnership typically involve promises — vows to love, honor, and remain faithful to a partner. But can love be promised? Love is not obviously under voluntary control in the way that many actions are. Can one sincerely promise to feel something that may or may not persist regardless of one’s will?

10.1.1 The Voluntariness Problem

Michael Bratman and others in the philosophy of intention distinguish between actions, which are under direct voluntary control, and states, which may be only indirectly controllable. Emotions and feelings typically fall into the latter category. I can promise to act lovingly — to show up, care for, and support my partner — but can I promise to feel love?

One response is that wedding vows are best interpreted not as promises to feel love but as commitments to act lovingly (以愛的方式行動) regardless of the vicissitudes of feeling. This is a defensible interpretation, but it raises the question of whether such action-commitments capture what we care about in romantic love.

10.2 Fidelity and its Grounds

Fidelity (忠誠) — commitment to a particular partner, typically including sexual exclusivity — is widely regarded as a virtue of committed romantic relationships. But what grounds fidelity? Three main accounts are available:

10.2.1 The Ethics of Infidelity

Philosophical analysis of infidelity (不忠) must distinguish several different wrongs it may involve: promise-breaking, deception (which is present whenever infidelity is concealed), betrayal of trust, harm to the partner’s interests, and the dignity-violation involved in using the partner as a means. These wrongs may not all be present in every case of infidelity, and their relative severity varies.

10.3 Long-Term Love and the Transformation of Desire

A recurring philosophical question about committed long-term relationships concerns whether the passion characteristic of early romantic love is compatible with the stability of lasting commitment. Some philosophers argue that mature love is fundamentally different from early romantic love — less passionate but deeper, less about excitement and more about attachment, care, and the integration of lives.

Aaron Ben-Ze’ev distinguishes between romantic intensity and romantic profundity: intensity refers to the heightened, often tumultuous quality of early love; profundity refers to the depth of understanding, acceptance, and interwovenness that can develop over long periods. On his view, a life spent in pursuit of romantic intensity is likely to be one of repeated beginnings rather than sustained love.

Chapter 11: Marriage — History, Politics, Philosophy

11.1 The Institution of Marriage

Marriage (婚姻) is among the most philosophically rich social institutions. It combines elements of contract, status, sacrament, and political institution. Its history across cultures and eras is enormously varied; what counts as marriage, who can marry, and what marriage entails have been subjects of ongoing legal, cultural, and philosophical contestation.

11.1.1 Historical Overview

In Western history, marriage has served at least three distinct functions: (1) economic — organizing property, inheritance, and household labor; (2) reproductive — establishing legitimate paternity and structuring child-rearing; (3) relational — providing a framework for intimate companionship and mutual support. These functions have historically been bundled together in the institution of marriage, but contemporary philosophers have asked whether this bundling is necessary or desirable.

11.2 Brake’s Minimizing Marriage

Elizabeth Brake’s Minimizing Marriage offers the most systematic contemporary philosophical analysis of marriage as a political and legal institution. Brake argues that the state’s interest in regulating marriage must be grounded in liberal principles — primarily in supporting networks of care and the conditions for human flourishing.

11.2.1 The Liberal Critique of Marriage

Brake’s argument reflects a broader liberal skepticism about state involvement in intimate life. The liberal tradition — from John Stuart Mill onward — holds that the state should remain neutral between different conceptions of the good life. Privileging the romantic dyad as the paradigmatic form of intimate association is, on this view, an illegitimate imposition of a particular cultural ideal.

Critics of this liberal approach argue that marriage serves important social functions — particularly the raising of children — that the state has legitimate interests in supporting. The conservative view holds that the traditional institution of marriage is not merely one lifestyle choice among others but a crucial social technology for organizing reproduction and child-rearing.

11.2.2 Same-Sex Marriage

The philosophical debate about same-sex marriage (同性婚姻) intersects with broader debates about the nature and purpose of marriage. Those who define marriage in terms of its procreative function (often following natural law theory) have argued that same-sex marriage is not genuine marriage. Brake and most contemporary liberal philosophers reject this position: if the state’s interest is in supporting caring relationships and the conditions for human flourishing, there is no principled basis for excluding same-sex couples.

11.3 Marriage, Gender, and Power

Feminist philosophers have long argued that the institution of marriage, as historically practiced, is a mechanism for the oppression of women. The legal coverture doctrine — which until the nineteenth century merged a wife’s legal identity with her husband’s, eliminating her capacity to own property, enter contracts, or sue — is an extreme example, but feminists argue that subtler patterns of gender inequality persist in contemporary marriage.

Iris Marion Young’s critique of marriage focuses on the way it channels women’s care labor — child-rearing, domestic work, emotional labor — into a private sphere that receives no social recognition or compensation. Susan Okin’s Justice, Gender, and the Family (1989) argues that the family is a site of significant injustice that liberal political philosophy has systematically ignored.

Chapter 12: Polyamory and Non-Monogamy

12.1 What is Polyamory?

Polyamory (多元愛) is the practice of engaging in multiple simultaneous romantic or sexual relationships with the knowledge and consent of all parties involved. It is distinguished from infidelity by its commitment to transparency and from other forms of non-monogamy (such as swinging) by its emphasis on emotional intimacy as well as sexual involvement.

12.2 Philosophical Arguments For and Against Polyamory

12.2.1 Arguments For

Several philosophical arguments support the moral permissibility, and perhaps even the value, of polyamory:

The Autonomy Argument: Consenting adults should be free to structure their intimate lives as they choose. If multiple partners consent to a polyamorous arrangement, there is no victim and no harm to justify prohibition or social disapproval.

The Love-Scarcity Objection Refuted: A common objection to polyamory is that love is a finite resource — loving multiple people necessarily means loving each less. Defenders of polyamory argue this is false: parental love for multiple children does not diminish with each additional child. The analogy to multiple romantic loves is imperfect but suggestive.

Jenkins’s Dual Nature Theory: If romantic love has a social nature that is shaped by norms and institutions, then the norm of monogamy is itself a social construction that may not represent the only or best way to organize loving relationships. Jenkins herself has written about polyamory as one of the alternative relationship structures that her dual nature theory opens up philosophical space for.

12.2.2 Arguments Against

Critics of polyamory offer several arguments:

The Depth Argument: The union and merger theorists (Nozick, Solomon) may hold that genuine romantic love requires a kind of full mutual investment — a “we” — that is incompatible with multiple simultaneous romantic attachments. If love involves the formation of a new shared identity, having multiple such relationships may be structurally impossible or self-undermining.

The Jealousy Objection: While polyamory advocates often present jealousy as a social construction that can be “unlearned,” critics argue that jealousy reflects genuine attachment and concern for the exclusivity that deep intimacy seems to require. The ideal of compersion (喜他所喜), while admirable, may be psychologically unrealistic for most people.

Feminist Concerns: Some feminist philosophers have raised concerns that polyamory, in practice, often reproduces gender inequalities — with men having more latitude to pursue multiple relationships while women bear disproportionate emotional labor costs. Whether this is an objection to polyamory in principle or an objection to its current social practice is contested.

12.3 Non-Monogamy, Marriage Law, and Pluralism

Brake’s minimal marriage argument has natural implications for plural relationships: if the state’s interest is in supporting networks of care without privileging any particular configuration, there is no principled basis for restricting marriage to dyadic arrangements. Brake stops short of advocating polygamous marriage but argues that the state should recognize care networks of various configurations.

12.4 Love, Commitment, and Alternative Futures

The study of polyamory and non-monogamy raises the broadest philosophical questions about the future of love and commitment. If romantic love has a social dimension that is culturally malleable (Jenkins), if marriage is a political institution that can be reformed (Brake), and if consent and well-being are the relevant moral criteria (Wertheimer, Nussbaum), then the forms that love and commitment take are genuinely open to reconstruction.

This does not mean that any configuration is equally valuable. The philosophical task is to identify the conditions — of autonomy, mutual recognition, care, honesty, and equity — under which intimate relationships of whatever configuration can be genuinely flourishing rather than merely formally consensual.