Firestone wrote the most uncompromising book of second-wave feminism at twenty-five, helped found three of its central organizations, and then left the movement entirely.
The Dialectic of Sex (1970) applies a materialist method to a base Marx had not considered. Class analysis, she argued, had located the fundamental division in the relations of production; the deeper division is in the relations of reproduction — the biological fact that women bear children and are made dependent during it, from which the family, and through the family every subsequent hierarchy, is modeled. Her conclusion is that no redistribution of social roles reaches the root, because the root is biological, and that liberation therefore requires the technological abolition of the reproductive difference itself: artificial gestation, the dissolution of the biological family, and the end of childhood as a separate dependent condition.
It is a genuinely radical argument in the literal sense and was controversial inside feminism immediately, both for conceding that biology is the foundation — which many thought handed the case to opponents — and for the coldness of the remedy. Later feminist theory largely moved to social construction and away from her; the rise of reproductive technology has made her look less eccentric than she did.
She was a founder of New York Radical Women, Redstockings and New York Radical Feminists, which put her at the organizational center of the movement's most productive years. She then withdrew, spent decades in and out of psychiatric hospitals, and published almost nothing further; Airless Spaces (1998) is a short, bleak set of sketches of institutional life. She died alone in her apartment in 2012.