| Below is a list of some of the more notable philosophers of science. Please bear in mind that it is sometimes extremely difficult to say where philosophy ends and science begins, and so create a hard and fast rule as to who constitutes a 'philosopher of science'. As a rule of thumb, I've included those philosophers who have turned their attentions to the thing commonly called 'science', and those scientists who have attempted to take a step back from their work and question its validity in the grander scheme of things. That is, those scientists who have attempted to look at their work philosophically.
Annotations are intended to arouse your interests, not to satisfy them. As such, they are necessarily incomplete (have you tried explaining the importance of Descartes in fifteen words?). For more information, visit the nodes themselves, many of which contain truly excellent writing.
Aristotle
(384-322 B.C.) One of the all-time greats, Aristotle is included here for his application of philosophy to the practical, physical world, particularly in the area of biology. He arguably got science out of the forum and into the field.
A.J. Ayer
(1910-1989) British Logical Positivist, and originator of the verifiability principle.
Francis Bacon
(1561-1626) A true renaissance man, Bacon is included here for his application of inductive reasoning, which formed the basis of subsequent scientific work.
Niels Bohr
(1885-1962) Danish physicist and philosopher, particularly noted for his principle of complementarity.
Rudolf Carnap
(1891-1970) Member of the Vienna Circle and a Logical Positivist, Carnap did a lot of work on what constitutes a scientific theory, and also what can be considered a 'fact'. He was one of the main supporters of the verification principle.
Auguste Comte
(1798-1857) French philosopher and the father of modern sociology. Scientifically, he is mainly remembered for his role in establishing positivism (the precursor to logical positivism).
René Descartes
(1596-1650) The father of modern philosophy, Descartes was arguably the first to seek scientific justification for his philosophical beliefs.
Paul Feyerabend
(1924-94) Advocate of epistemological anarchy, an attempt to criticise the cosy, institutionalised world of modern science.
Michel Foucault
(1926-1984) Although perhaps more of a philosopher of the social sciences, Foucault's work sheds light on the relationship between power and truth, which is obviously significant within the field of science.
Bas van Fraassen
(1941-....) American logician and philosopher of science, working at Princeton University, who's work attempts to find a middle ground between Carnap and Putnam
Gottlob Frege
(1848-1925) The founder of modern logic. Despite numerous criticisms from Russell and others, Frege's work is still the root of most philosophy of mathematics, set theory and logic.
Martin Heidegger
(1889-1976) German phenomenologist. Although not primarily a philosopher of science, he is included here for his work connecting modern science to enlightenment modes of thinking, particularly in the paper 'What is a thing?'
Werner Heisenberg
(1901-1976) German physicist, responsible for the Uncertainty Principle.
Douglas Hofstadter
(1945-....) American mathematician and philosopher, included here largely for his mathematical approach to the philosophy of mind, and his contributions to the excellent anthology The Mind's I.
David Hume
(1711-1776) Scottish philosopher famed both for his strongly atheist views and his arguments against causality, which still cause problems for philosophers of science today.
Immanuel Kant
(1724-1804) German philosopher. Among the most influential philosophers of all time, Kant's divisions of 'synthetic' vs. 'analytic' and 'noumenal' vs. 'phenomenal' have kept scientists and philosophers alike busy for many years.
Philip Kitcher
(1947-....) Contemporary British philosopher of science currently lecturing at Columbia University. His interests include the apparent conflict between science and religion.
Thomas Kuhn
(1922-1996) One of the most important modern philosophers of science, he came up with a model to explain how scientific beliefs changed over time, and coined the phrase 'paradigm shift'.
Imre Lakatos
(1922-1974) Hungarian mathematician and logician, who attempted to refine and improve Popper's work.
Bruno Latour
(1947-....) Contemporary French writer, described in cabin fever's excellent write-up as a 'sociologist of science'.
Blaise Pascal
(1623-1662) French mathematician, who also turned his scientific eye towards more philosophical issues, resulting in his famous wager.
Karl Popper
(1902-1994) One of the most influential philosophers of science, his work (especially his belief that, in order to qualify as scientific, a theory must be fasifiable) is closely related to logical positivism.
Pythagoras
(approx. 570 B.C. to 480 B.C.) Greek mathematician and philosopher. Although little is known about his work, it seems that he was among the first people to believe that nature followed mathematical laws. Obviously, this is a central tenet of modern science, and so his arguments could perhaps be considered the first philosophy of science.
Willard Van Orman Quine
(1908-2000) American philosopher of science (and almost everything else). His philosophy of science was holistic, and as such refuted the work of Popper. The idea of ontological relativity also poses some interesting questions concerning the truth.
Bertrand Russell
(1872-1970) British philosopher, most famous for his vocal political opinions, but he also did some very important work in the philosophy of mathematics earlier in his career.
C. P. Snow
(1905-1980) British writer and scientist, who's main contribution to the philosophy of science was the distinction between 'The Two Cultures' of the humanities and the sciences.
Ludwig Wittgenstein
(1889-1951) Usually considered a philosopher of language (which is, in fact, incorrect. /msg me if you care to argue the point...), Wittgenstein's later work contained his arguments against Logical Positivism. The logical positivists themselves claimed Wittgenstein as their founding father, so his refutations proved a trifle embarrasing.
This list is far from complete. Please /msg me if you have further philosophers of science to add, or if I have made any mistakes in the annotation.
With thanks to E2Science, ataraxia, cabin fever, Glowing Fish, JerboaKolinowski and Oolong. | 
