In 1999, philosopher Douglas Lackey asked thousands of philosophers to name what they considered to be the 5 most important books and the 5 most important articles in 20th century philosophy. The most-cited books were:

1. Wittgenstein, Philosophical Investigations [179 citations]
2. Heidegger, Being and Time [134]
3. Rawls, A Theory of Justice [131]
4. Wittgenstein, Tractatus Logico-Philosophicus [77]
5. Russell & Whitehead, Principia Mathematica [64]
6. Quine, Word and Object [63]
7. Kripke, Naming and Necessity [56]
8. Kuhn, The Structure of Scientific Revolutions [51]
9. Sartre, Being and Nothingness [38]
10. Whitehead, Process and Reality [34]
11. Ayer, Language, Truth, and Logic [30]
12. Dewey, Experience and Nature [25]
13. Merleau-Ponty, Phenomenology of Perception [23]
14. Moore, Principia Ethica [19]
15. James, Pragmatism [18]
16. MacIntyre, After Virtue [18]
17. Husserl, Logical Investigations [17]
18. Husserl, Ideas [17]
19. de Beauvoir, The Second Sex [17]
20. Hart, The Concept of Law [14]
21. Ryle, The Concept of Mind [14]
22. Goodman, Fact, Fiction, and Forecast [13]
23. Gadamer, Truth and Method [12]
24. Parfit, Reasons and Persons [12]
25. Russell, The Problems of Philosophy [11]
26. Quine, From a Logical Point of View [11]
27. Popper, Logic of Scientific Discovery [11]