I know that Russell was a great ambassador, but where exactly was he influential as a philosopher? Putting him in the Top 10 based on his role as a spokesman would be like putting Carl Sagan in the Top 10 of a Greatest Physicists list. If he is that influential though, I'd replace Chomsky with him.
Is he really that much more influential than Kierkegaard, who influenced practically every philosopher after him in some way? Yes, existentialism isn't in nearly as much favor as it used to be, but it still appears in some postmodern and surreal works and quite a bit of people still have that kind of a philosophy.
What would your revised, Top 10-20 look like?
Russell's influence in philosophy of mathematics is staggering (think of the Principia Mathematica
). He is still routinely cited in arguments by atheists (see Russell's teapot, for one). His work in philosophy of language provided a jumping off point for the early Wittgenstein, and also the logical positivists. He was a staunch defender of the correspondence theory of truth (against various others, such as pragmatists like Dewey). He was a key figure in counter-acting Kantian epistemology.
Many of Russell's arguments and positions have largely been superseded, but were essential in getting philosophy to where it is now. It's not just that he's the field's greatest ambassador—he is that and
one of its greatest practitioners.
And, while Kierkegaard is hugely influential in philosophy of religion, existentialism, and many strains of "continental" philosophy, his influence on "analytic" philosophy is much smaller. What does he have to say to a Dennett or a Searle? He is certainly tremendously influential and a reasonable top ten candidate, but to say he's influenced "almost every" subsequent philosopher is stretching it. I think Russell's influence in more analytic philosophy is comparable to Kierkegaard's in continental (these distinctions are crude, but reasonably useful for my purposes, I think), and probably greater simply because Russell's breadth is far greater than Kierkegaard's.
Here's a revised, but still very rough top 10.
3. Immanuel Kant (I could see him at either 2 or 3, really)
4. Friedrich Nietzsche
5. Thomas Aquinas
6. David Hume
7. Rene Descartes (he could move down slightly simply because basically none of his arguments are accepted anymore, even though he deserves a high spot for marking the start of modern philosophy)
8. Bertrand Russell
9. Soren Kierkegaard
10. St. Augustine
No order yet, but some I think could potentially be in the top 20 (questionable ones marked with ???):
Georg Hegel (potentially top 10, I might move him in instead of Descartes)
Ludwig Wittgenstein (at the forefront of two of the major trends in 20th century philosophy, definitely high up)
John Dewey (??? - probably near the bottom of the top 20 if in at all)
Martin Heidegger (??? - same as Dewey)
John Rawls (definitely a top 20 inclusion)
Thomas Kuhn (probably low top 20, but he should probably be the highest philosopher of science)
Gottlob Frege (??? - I'm not too sure about precisely how important he is)
Karl Popper (??? - Definitely hugely influential, but his basic project is generally considered a failure now)
Michel Foucault (really unsure about him)
St. Anselm (??? - just not sure how big he is compared to Aquinas and Augustine)
Noam Chomsky (??? - not sure how important he is to philosophy specifically, compared to linguistics and political science, which are related subjects, of course, but not strictly philosophy)
John Locke (a top 20 lock, I think, for his influence on empiricism and his continuing huge influence on political philosophy, including the actual implementation of political philosophy in countries such as the U.S.)
John Stuart Mill (major contributions to logic and ethical philosophy, influence on American pragmatism, continuing influence to today, another top 20 lock)
Ralph Waldo Emerson (??? - more of a popular influence and impact than within academic philosophy, not sure how to weight that)
Karl Marx (??? - because his main contributions are to economics and history, as I understand it, even though many philosophers draw on him)