This book, first published in 1969, examines the 'philosophies of existence' or Existentialism and the field's leading philosophers. These philosophers, the book argues, wished to distinguish themselves from other philosophies in their structure and approach - and it is that structure that this book takes care to analyse.

1. Generalities 2. The Traditions Leading to the Philosophies of Existence 3. The Traditions to which the Philosophies of Existence are Opposed 4. General Evolution of the Philosophies of Existence 5. The First Triad: Existence, Being, Transcendence 6. The Second Triad: Possibility and Project, Origin, Now/Situation/Instant 7. The Third Triad: Choice and Freedom, Nothingness and Dread, Authenticity 8. The Unique, the Other, Communication 9. Truth-Subjectivity, Truth-Being, Multiplicity of Truths 10. Paradox, Tension, Ambiguity 11. Comprehensive View 12. The Ultimate Problems of the Philosophies of Existence