It cannot be easy having a 1981 thesis being read by professional historians decades later. But there appears to be universal consent that her work holds up remarkably well:

On the whole, Kagan writes without evident bias, analyzing quite evenhandedly the riftswhich at times she suggests were doomed to be insurmountablebetween the revolutionary and reformist camps in the Socialist Party as well as in the International Ladies Garment Workers' Union. If anything, Kagan seems to have more sympathy for the centrist "constructivist" leadership than do many historians who write about labor and radicalism. Her overall point, made without stridency, is that sectarianism, caused mainly by misguided revolutionary hopes, should ultimately bear the burden for the party's demise. Socialists, she seemed to say with some sadness and frustration, have often been their own worst enemies. In places, her tone even implies that she may consider this an ongoing characteristic of the American left. "Radicals have often succumbed to the devastating bane of sectarianism," she wrote; "it is easier, after all, to fight one's fellows than it is to battle an entrenched and powerful foe." In any case, there is no question that Kagan wrote not a propagandistic celebration of socialism's heyday but a judicious account of its self-destructionwith the hope that the left might learn from past mistakes.

There can be few doubts about her intellectual abilities.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.