Beauvoir opens her analysis by posing a foundational question: what exactly is a woman?

Beauvoir argues women are 'the Other' — defined only in relation to men, not as autonomous beings in their own right.

Beauvoir examines biological science and concludes that women's reproductive biology alone cannot explain their global subordination to men.

Beauvoir critiques psychoanalysis for defining female sexuality entirely through women's relationships with their parents rather than independently.

Beauvoir critiques Engels's theory, arguing that the rise of private property alone cannot fully account for women's oppression.

Beauvoir argues that even in prehistoric societies, women held only spiritual and advisory roles and were never genuinely politically powerful.

Beauvoir argues the rise of private property transformed women from mystical figures into subordinate servants belonging to men.

Beauvoir argues Christianity worsened women's condition by associating women with sexual temptation, earthly sin, and the devil.

Beauvoir argues that the Industrial Revolution and growing access to birth control began transforming women's social and economic condition.

Beauvoir introduces the myths surrounding women, describing them as ambiguous and contradictory — casting women as both wholly good and evil.

Beauvoir opens Volume II by outlining the life of an archetypal woman, traced from early childhood through old age.

Beauvoir argues that girls are indoctrinated into femininity from early childhood through their upbringing, education, fairy tales, and religion.

Beauvoir argues that marriage confines women to the domestic sphere and makes them economically dependent on their husbands.

Beauvoir argues that motherhood, when not freely chosen, strips women of their remaining freedom and demands submission to husbands.

Beauvoir concludes that women's true emancipation requires economic independence, reproductive freedom, and deep moral, social, and cultural transformation.

Beauvoir opens The Second Sex by asking what a woman fundamentally is, then argues that women are not defined in their own right but only in relation to men — they are 'the Other.' She systematically examines and rejects biology, psychoanalysis, and Marxist history as complete explanations for women's subordination, finding each insufficient on its own. Her historical survey shows that women were never truly politically powerful, not even in prehistoric or matriarchal societies, and that forces like private property and Christianity progressively worsened their condition. Beauvoir then identifies the myths surrounding women as a powerful cultural force that perpetuates oppression across all of society. In Volume II, she traces the arc of a typical woman's life, showing how femininity is imposed through childhood, marriage, and motherhood. She concludes that only economic independence, reproductive freedom, and a sweeping cultural transformation can bring about women's genuine emancipation.

The core argument: how women became the Other

Beauvoir notes that modern science has undermined the belief that groups like women, Jews, and Black people have innate defining traits.

Beauvoir observes that female mammals after giving birth sacrifice their individual freedom to the demands of the species, unlike males.

Beauvoir argues the human woman is the most biologically alienated female mammal yet also resists that alienation most fiercely.

Beauvoir rejects the theory that ancient matriarchal societies represented a genuine reign of women with true political dominance.

Beauvoir cites the Babylonian myth of Tiamat, a primordial goddess slain by the god Marduk, as reflecting male domination over female nature.

Beauvoir argues women fared better in societies like ancient Sparta, where strong central government limited the independent authority of individual families.

Beauvoir argues the French Revolution failed to extend its promises of liberty and equality to women.

Beauvoir describes how Napoleon's legal regime stripped women of rights to become lawyers, obtain divorces, and maintain various other freedoms.

Beauvoir argues that writers like Montherlant portray women as 'night, disorder, and immanence,' reinforcing ancient myths of female nature.

Beauvoir praises Stendhal as the only major male writer who presents women simply as human beings, free of feminine mythology.

Beauvoir argues adolescent girls develop a narcissistic 'cult of the self,' expressed through diary-writing, to privately assert their individuality.

Beauvoir argues that women's first sexual experience typically transforms them into a 'carnal object,' regardless of the partner's behavior.

Beauvoir argues the institution of marriage is 'perverted at its base,' meaning the structural problem goes beyond individual unhappy couples.

Beauvoir argues older women discover freedom once domestic duties no longer define their lives, but can find nothing meaningful to do with it.

Beauvoir argues societal restrictions prevent women in creative fields from ever producing figures comparable to Kafka or Van Gogh.

Beauvoir builds her argument with a series of significant observations spanning science, history, literature, and lived experience. She begins by noting how modern science had already undermined beliefs in innate group characteristics, while also observing that female biology creates a unique alienation that women resist fiercely. Moving through history, she challenges the romance of prehistoric matriarchies, illustrates how ancient myths encoded male dominance over female nature, and shows how Sparta and Rome offered women better conditions than most societies managed. She traces the failure of the French Revolution and Napoleon's legal rollbacks to demonstrate how political progress repeatedly bypassed women entirely. Beauvoir then analyzes male writers from Montherlant to Stendhal, revealing how even acclaimed literature either reinforces or occasionally defies feminine myths. Finally, she follows a woman's life through adolescent narcissism, traumatic sexual initiation, a marriage structurally flawed at its foundation, into an old age where freedom arrives too late and creative ambition has already been permanently stunted.

Significant arguments behind the central thesis

Beauvoir rejects personal happiness as the measure of women's emancipation, proposing instead the existentialist concepts of transcendence and immanence.

Beauvoir reveals that men require women as the Other to define themselves, since Nature is too abstract and other men too identical.

Beauvoir argues myths place women between opposites like Eve and the Virgin Mary, serving men's psychological needs rather than reflecting reality.

Beauvoir argues that myths about women do not just shape male behavior — they block women's own roads to transcendence from within.

Beauvoir opens Volume II by declaring that women are beginning to affirm their independence concretely but still struggle to live freely.

Beauvoir introduces the claim that 'one is not born, but rather becomes, woman,' as the foundation of her analysis of childhood.

Beauvoir argues lesbianism is 'an attitude chosen in situation' — not simply a fear of men or a rejection of femininity.

Beauvoir argues that wives who take lovers or form close female friendships still cannot break the fundamental constraints of marriage.

Beauvoir argues sex workers suffer deplorable material conditions rather than moral failure, yet remain just as dependent on men as wives.

Beauvoir argues that women themselves actively uphold the masculine world, having been thoroughly conditioned to accept their own helplessness.

Beauvoir argues women resist male dominance through 'contrariness' — refusing to play the game because they know the dice are loaded.

Beauvoir argues narcissism traps women in alienation, making the self an absolute end and preventing authentic engagement with the wider world.

Beauvoir argues genuine love between women and men is only possible when women can love from strength rather than weakness or resignation.

Beauvoir points to the Soviet Union as the nation that came closest to her vision by legalizing abortion and promoting women's employment.

Beauvoir declares 'the free woman is just being born,' expressing confidence that full female emancipation is imminent but not yet achieved.

Beauvoir's most pivotal intellectual moves reveal the deeper mechanisms of women's oppression and the precise conditions required for their freedom. She establishes at the outset that transcendence — not happiness — is the true measure of liberation, then later uncovers why men psychologically require women as the Other to define themselves at all. The myths she describes are shown to operate on women from the inside, blocking their own roads to self-understanding, not merely shaping how men perceive them. In Volume II, Beauvoir reveals that becoming a woman is never natural but always socially constructed, and shows how seemingly defiant choices — lesbianism, adultery, sex work — still leave women fundamentally defined by their relationship to men. She traces how women internalize their own subordination, resist it through indirect and symbolic means, and trap themselves in narcissism or religious devotion as substitutes for genuine freedom. The book closes with cautious optimism: genuine love, Soviet-style economic reform, and the emerging independent woman suggest that real emancipation, though not yet achieved, is finally on the horizon.