As I recall, Katrina Forrester’s In the Shadow of Justice gives externalist explanations of various developments in Rawls’s thought, i.e. explanations in terms of events in the larger political world post-WW II. And there could a more general “sociology of Rawls,” one that tries to explain the utter dominance of his ideas in so much of political philosophy for so many decades. (And no, this wasn’t just because of the quality of the ideas.) There’s first the matter of timing, i.e. A Theory of Justice came out at arguably the perfect time, both within philosophy and in the larger political world (e.g. student protests), to have its greatest impact. There’s Rawls’s position at Harvard, his apparently immense influence on his students, and their ability to find — or his ability to find them — influential positions at other top universities. Also the fact that Philosophy and Public Affairs was for a time essentially a Rawlsian house journal, and doubtless more. There just seems a lot of scope for at least partly externalist explanation of this familiar fact of recent philosophical history.

Forgive what is perhaps a naive question…but aren’t these “external explanations” just historical or sociological explanations? They are certainly not new. If, indeed, the new phenomenon is philosophers taking them more seriously, then: on the one hand, that’s great–philosophers, particularly anglo-american analytic philosophers (of which I am one), have generally been too ignorant of the larger historical, social, and intellectual context of philosophy. On the other hand, here lies a danger: these historical explanations should not be confused for evidence or reasons that a certain philosophical view is true or false, justified or unjustified. It might be the case that, say, Rawlsian liberal political philosophy was a response to the Cold War political situation in the US. But can that tell us anything about what we should think of Rawls’ arguments? Not really. The question of whether his arguments are good or not depends on the arguments themselves. Their historical, social, and intellectual context can gives us really valuable *clues* for where to look for possible weaknesses or deficiences of his arguments, but it cannot act as evidence against them or reasons to reject them, on their own. No more than we could use the fact that, say, Plato came from a well-to-do family to reject the theory of Forms.

Three thoughts. First, the notion of external and internal explanations bears some resemblance to Brandom’s reading of Hegel’s Phenomenology in A Spirit of Trust. For Hegel, it’s always possible to give a niedertraechtig or pusilanimous rational reconstruction of some intellectual development (or really any event), explaining it by way of factors external to the rational details of the ideas and the high-minded intentions of the agents — cf. the hermeneutics of suspicion. At the same time, it’s also always possible to give an edelmeutig or magnanimous rational reconstruction, which ascribes explanatory power to those reasons and intentions. It’s just in the nature of the kinds of beings we are, and the richness of the world, that such readings are both always available. For Brandom, trust results from a judicious application of these two attitudes, finding a way to ascribe sincerity to an actor’s stated intentions, and explanatory significance to what they say they were up to.

Second, regarding the sociology of analytic philosophy in the U.S., interested parties might look to Joel Katzav and Krist Vaesan’s work on the journal capture that took place at The Journal of Philosophy, Mind, and The Philosophical Review in the middle of the 20th century, shifting those journals from a pragmatist-inflected pluralism toward analytic philosophy. From p.774 of their “On the Emergence of American Analytic Philosophy”:

[This essay] suggests that analytic philosophy emerged in America at a time characterized by philosophical pluralism and a widespread commitment to addressing meta-philosophical issues related to such pluralism. It also suggests that analytic philosophy came to dominate American philosophy partly by analytical philosophers taking control of key institutions within academic philosophy and using these to promote analytic philosophy, and that crucial steps in the direction of such control occurred before 1950. The reason for the growing dominance of analytic philosophy appears to have been, at least in part, the suppression, by institutional means, of existing diversity and, possibly, the exploitation of American pluralism.

Finally, one place where an externalist explanation seems to me ripe is in the dominance of so-called “intensional semantics” downstream from Carnap’s appropriation of Leibniz’s term “intension” as an Ersatz for Frege’s notion of Sinn, and especially the work done at UCLA in the late 1960s, which at the time was home to Rudolph Carnap, Alonzo Church, Keith Donnellan, Donald Kalish, Hans Kamp, David Kaplan, David Lewis, Richard Montague, and Barbara Partee. Much of the work done in philosophy, linguistics, and cognitive science since that time has been blinkered by an exclusively denotational conception of meaning, at the expense of a properly intralinguistic or connotational one. The “hyperintensional revolution”, for instance, is largely an artifact of Carnap’s terminology, and the research programs devoted to the study of hyperintensions work within the conceptual space delimited by Carnap’s notion of intension as a function from state descriptions (an early analogue to possible worlds, minus the accessibility relations) to extensions.

I’m not sure how to give the edelmuetig compelment to that niedertraechtic externalist explanation for the dominance of Carnapian notions of intensionality in Anglophone analytic philosophy today, but I suspect it will come by way of an appreciation of Rorty’s anti-representationalist stance, and its influence on people like Brandom.

The impact of WWI on western philosophy. Before the War, it was normal for many British philosophers to study in Germany. That practice diminished after the War. It wasn’t all at once, but interaction between the two philosophical communities fell off. Tom Akehurst has written about the War’s impact (esp. in his book The Cultural Politics of Analytic Philosophy: Britishness and the Spectre of Europe).

In French philosophy journals from WWI, I found articles or letters in which French philosophers called for French philosophy to become pure, or truly French (viz., no more German influence). But German influence was stronger than in the UK partly because of Alsace-Lorraine (e.g., Jean Hering at Strasbourg) and because more Russian refugees moved to France. Some of these refugees had studied philosophy in Germany (e.g., Gurwitsch, Levinas, Koyré, Kojève). So, Husserl’s post-WWI talks in the UK met largely with polite indifference and his talks in France weren’t attended by many of the leading French philosophers, but they were channeled into French philosophy by Hering’s students and emigre Russians (see Ekaterina Shashlova’s paper “Russian philosophers in France in the interwar period: a review of the studies of emigrant philosophers”).

That’s not a complete explanation of why France remained more engaged with German philosophy than did the UK, but I think it’s essential to any full account. Major wars and large population migrations influenced 20th-Century philosophy.  

Also, the sheer number of promising young German philosophers who were lost in WWI. The Germans had to reach deeper into their male population to find enough soldiers, so many 30- and 40-something philosophers were on the front lines. Several British philosophers served in WWI, but mainly in the intelligence services. It’s harder to find any early or mid-career British philosophers who were killed in that War.

Focusing on or worrying about “externalist” explanations has been a common theme through much of the history of philosophy, as many have noted in the other comments. On this point, I would like to add Hume to the list. At the very least, Hume’s commentators now tend to agree that one of his core contributions is a well-developed view on the limits of efforts at belief change through philosophical argumentation. Some of his interest with skepticism just is an interest in why some arguments (namely, the “skeptical” ones) lack lasting purchase on the beliefs we form/have/keep. A more radical interpretation that I have been working to motivate lately is that Hume holds that our belief formation processes in philosophy are fundamentally the same kind as those which we use in the rest of our lives and, strikingly, they are those by which we reason causally. In a sense, this is the interpretation that Hume holds that philosophy must be “externalist” all the way down, given human nature as it is. (Drafts available upon request.)