UPDATE: Elena Kagan's thesis does not seem to have brought any clarity of thought. Interpretations of it seem to depend on whether the phrase "those who" (in "those who, more than half a century after socialism's decline, still wish to change America [in a radical way]") means "people like my advisor Sean Wilentz and my brother" or "people like my advisor and my brother and me."

I believe it is much more likely than not that "those who" carries the first meaning. Remember, she was crafting the thesis to resonate with those who would grade it--with Sean Wilentz and his colleagues. I think it highly probable that if she had placed herself among "those who" she would have used a different phrase: "we who."

I think that her takeaway from her thesis was Clintonian (and Obamaian): radicals in America need to shut up, take their place at an oar, and row like hell for minor reformist victories.

The thesis is, I believe, mostly an argument against Glenn Greenwald and his fears that Elena Kagan is really John Roberts in disguise...

From the introduction:

Ever since Werner Sombart first posed the question in 1905, countless historians have tried to explain why there is no socialism in America. For the most part, this work has focused on external factors--on features of American society rather than of American socialist movements. Socialists and non-socialists alike have discussed the importance of the frontier... the fluidity of class lines... the American labor force's peculiarly heterogeneous character, which made concerted class action more difficult than it might otherwise have been. In short, most historians have looked everywhere but to the American socialist movement itself for explanations of U.S. socialism's failure. Such external explanations are not unimportant but neither do they tell the full story. They ignore or overlook one supremely important fact: Socialism has indeed existed in the United States.... The Socialist Party increased its membership from a scanty 10,000 in 1902 to a respectable 109,000 in the early months of 1919... a party press that included over three hundred publications with an aggregate circulation of approximately two million.... The success of the socialists in establishing a viable--if minor--political party in the early twentieth century suggests that historians must examine not only external but also internal factors if they hope to explain the absence of socialism from contemporary American politics. The effects of the frontier, of class mobility, of an ethnically divided working class may explicate why the Socialist Party did not gain an immediate mass following; they cannot explain why the growing and confident American socialist movement collapsed.... We are, then, left with three ultimately inadequate explanations of the sudden demise of a growing socialist movement. The otherworldliness of the socialists, the expulsion of Haywood in 1912, the Russian Revolution of 1917--none will satisfactorily explain the death of social- ism in America. What, then, was responsible? In attempting to answer this question, this thesis will focus almost exclusively on the history of the New York City local of the Socialist Party.... The collapse of New York socialism, although sudden, had deep roots indeed. From its first days, the New York SF was both divided within itself and estranged from many of its trade-union followers. Among the party's members, a right-left cleavage arose early--a cleavage based not on the minutiae of dogma but on the very fundamentals of socialism itself. What was the proper class composition of a socialist party? What trade-union and electoral policies should the party follow? What attitude should the party take toward distinctly non-radical reform measures?... At the end of 1918, old disputes quickly reappeared, but this time in even fiercer form. For years, large numbers of the SP's members and large blocs of its trade-union support had expressed deep dissatisfaction with socialist leadership. Now, the Russian Revolution set the spark... and the Socialist Party burst into flames. In 1919, the SP split into two.... Intra-party sectarianism had previously weakened the socialist movement; inter-party sectarianism now finished the job...

And from the conclusion: