Primary Sources – Philosophy During and Around the 20th Century

The Life of the Mind by Hannah Arendt

Language, Truth, and Logic by A.J. Ayer

The Problem of Knowledge by A.J. Ayer

Selected Writings of Jean Baudrillard

The Ethics of Ambiguity by Simone de Beauvoir

An Introduction to Metaphysics by Henri Bergson

Matter and Memory by Henri Bergson

Time and Free Will by Henri Bergson

I and Thou by Martin Buber

The Myth of Sisyphus and Other Essays by Albert Camus

The Rebel by Albert Camus

Language and Mind by Noam Chomsky

The God Delusion by Richard Dawkins

Nietzsche and Philosophy by Gilles Deleuze

What is Philosophy? by Gilles Deleuze & Félix Guattari

Consciousness Explained by Daniel Dennett

Darwin’s Dangerous Idea by Daniel Dennett

The Intentional Stance by Daniel Dennett

Speech and Phenomena & Other Essays by Jacques Derrida

Dissemination by Jacques Derrida

Of Grammatology by Jacques Derrida

Against Method by Paul Feyerabend

The Archaeology of Knowledge & The Discourse on Language by Michel Foucault

The Order of Things by Michel Foucault

Selected Writings of Mahatma Gandhi

The End of Faith by Sam Harris

The Moral Landscape by Sam Harris

The Condition of Postmodernity by David Harvey

God is Not Great by Christopher Hitchens

Logical Investigations by Edmund Husserl

Does Consciousness Exist? by William James

What Pragmatism Means by William James

The Varieties of Religious Experience by William James

The Will to Believe by William James

Reason and Existenz by Karl Jaspers

Last Writings: Nothingness and the Religious Worldview by Nishida Kitarō

We Have Never Been Modern by Bruno Latour

The Levinas Reader edited by Sáun Hand

The Self-Overcoming of Nihilism by Keiji Nishitani

Philosophical Explanations by Robert Nozick

Man Has No Nature by José Ortega y Gasset

The Language Instinct by Steven Pinker

Word and Object by W.V. Quine

The Virtue of Selfishness by Ayn Rand

Contingency, Irony, and Solidarity by Richard Rorty

Philosophy and the Mirror of Nature by Richard Rorty

In Praise of Idleness by Bertrand Russell

Mysticism and Logic: And Other Essays by Bertrand Russell

On Denoting by Bertrand Russell

The Problems of Philosophy by Bertrand Russell

The Concept of Mind by Gilbert Ryle

Being and Nothingness by Jean-Paul Sartre

Critique of Dialectical Reason: Volume I by Jean-Paul Sartre

Critique of Dialectical Reason: Volume II (Unfinished) by Jean-Paul Sartre

Existentialism is a Humanism by Jean-Paul Sartre

My View of the World (Excerpt) by Erwin Schrödinger

Athens and Jerusalem by Lev Shestov

The Ego and His Own by Max Stirner

The Courage to Be by Paul Tillich

The Eternal Now by Paul Tillich

Weak Thought edited by Gianni Vattimo and Pier Aldo Rovatti

The Wisdom of Insecurity by Alan Watts

Process and Reality by Alfred North Whitehead

Philosophical Investigations by Ludwig Wittgenstein

Tractatus Logico-Philosophicus by Ludwig Wittgenstein

Note: You can find 135 free philosophy e-books and free online philosophy courses at Open CultureProject Gutenberg and Internet Archive both host vast libraries of e-books for free to the public.