These are rounded to the nearest 100. I tried to find all post-WWII philosophy books with at least 5,000 citations. Clearly, cross-disciplinary interest causes the cite count to surge (contrast, e.g., David Lewis with Alasdair MacIntyre). You can post additions or corrections in the comments, which are open below.
1-10
Thomas Kuhn, The Structure of Scientific Revolutions (1962) (89,500)
John Rawls, A Theory of Justice (1971) (65,000)
J.L. Austin, How to Do Things with Words (1962) (35,200)
John Searle, Speech Acts (1969) (23,100)
Alasdair MacIntyre, After Virtue (1981) (21,400)
John Rawls, Political Liberalism (1993) (17,000)
Robert Nozick, Anarchy, State & Utopia (1973) (16,800)
Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge (1963) (15,700)
Ronald Dworkin, Taking Rights Seriously (1978) (15,400)
Gilbert Ryle, The Concept of Mind (1949) (15,200)
11-20
H.L.A. Hart, The Concept of Law (1961) (13,400)
Charles Taylor, Multiculturalism and the Politics of Recognition (1994) (13,100)
Richard Rorty, Philosophy and the Mirror of Nature (1979) (12,900)
Jerry Fodor, The Modularity of Mind (1983) (12,800)
Saul Kripke, Naming and Necessity (1980) (11,400)
Daniel Dennett, Consciousness Explained (1991) (11,100)
W.V.O. Quine, Word and Object (1960) (10,300)
Richard Rorty, Contingency, Irony and Solidarity (1989) (10,300)
Charles Taylor, Sources of the Self (1989) (10,300)
Karl Popper, Objective Knowledge: An Evolutionary Approach (1972) (10,100)
21-30
Paul Feyerabend, Against Method (1975) (9,900)
Karl Popper, The Open Society and Its Enemies (1945) (9,500)
John Searle, The Construction of Social Reality (1995) (8,400)
Derek Parfit, Reasons and Persons (1984) (8,200)
David Chalmers, The Conscious Mind (1996) (7,400)
Jerry Fodor, The Language of Thought (1975) (7,300)
Daniel Dennett, Darwin's Dangerous Idea (1995) (7,000)
Martha Nussbaum, Women and Human Development: The Capabilities Approach (2001) (6,900)
Hubert Dreyfus, Stuart Dreyfus & T. Athanasiou, Mind over Machine (2000) (6.800)
John Searle, Intentionality (1983) (6,500)
31-47
Daniel Dennett, The Intentional Stance (1987) (6,400)
Carl Hempel, Aspects of Scientific Explanation (1965) (6,300)
Hubert Dreyfus & Paul Rabinow, Michel Foucault: Beyond Structuralism and Hermeneutics (1983) (6,200)
John Rawls, The Law of Peoples (2001) (6,200)
John Rawls, Justice as Fairness: A Restatement (2001) (6,100)
Susanne Langer, Philosophy in a New Key (1951) (6,000)
Ronald Dworkin, Law's Empire (1986) (5,900)
David Lewis, Convention (1969) (5,900)
Nelson Goodman, Languages of Art (1968) (5,800)
Thomas Nagel, The View from Nowhere (1986) (5,800)
Bas van Fraassen, The Scientific Image (1980) (5,800)
David Lewis, Counterfactuals (1973) (5,400)
Peter Spirtes, Clark Glymour & Richard Scheines, Causation, Prediction and Search (2000) (5,300)
John Finnis, Natural Law and Natural Rights (1980) (5,200)
John Searle, Minds, Brains & Programs (1980) (5,200)
David Lewis, On the Plurality of Worlds (1986) (5,100)
Joseph Raz, The Morality of Freedom (1986) (5,100)
