Simone de Beauvoir's feminist philosophy was significantly influenced by her personal experiences and relationships, particularly with existentialist philosopher Jean-Paul Sartre. Her upbringing in a traditional French family highlighted the restrictive nature of gender roles, inspiring her to challenge societal norms. Beauvoir's exploration of female identity and freedom is encapsulated in her seminal work, "The Second Sex," where she articulates women as "the other." Her lived experiences, including her education and interactions with intellectual circles, shaped her advocacy for women's rights and helped lay the foundation for modern feminist thought.