A
- A Priori and A Posteriori
- Abelard, Peter
- Abortion
- Academy, The
- Active Powers
- Addams, Jane
- Adorno, Theodor
- Advaita Vedānta
- Aenesidemus
- Aesthetics
- Aesthetic Attitude
- Aesthetics of Popular Music
- Aesthetics, Medieval Theories of
- Agamben, Giorgio
- Alexander Polyhistor
- Alexander, Samuel
- Altruism and Group Selection
- American Enlightenment Thought
- American Philosophy
- American Transcendentalism
- Analytic Philosophy
- Anaxagoras
- Anaxarchus
- Anaximander
- Anaximenes
- Ancient Greek Philosophy
- Ancient Greek Skepticism
- Animal Minds
- Animals and Ethics
- Anomalous Monism, Mind and
- Anscombe, G.E.M.
- Anselm of Canterbury
- Antisthenes
- Aquinas, Thomas
- Aquinas: Ethics
- Aquinas: Metaphysics
- Aquinas: Politics
- Aquinas: Theology
- Arcesilaus
- Arendt, Hannah
- Argument
- Aristippus
- Aristotle
- Aristotle: Biology
- Aristotle: Ethics
- Aristotle: Logic
- Aristotle: Metaphysics
- Aristotle: Motion and its Place in Nature
- Aristotle: Poetics
- Aristotle: Politics
- Arnauld, Agnes
- Arnauld, Angélique
- Art and Epistemology
- Art, Ethical Criticism of
- Artificial Intelligence
- Astrology, Hellenistic
- Atheism
- Augustine
- Augustine’s Social and Political Philosophy
- Aurelius, Marcus
- Autism
- Autonomy
- Autonomy: Normative
- Averroes (Ibn Rushd)
- Avicenna (Ibn Sina)
- Aztec Philosophy