What is the theme in Gender Trouble: Feminism and the Subversion of Identity by Judith Butler?

The main thesis of Gender Trouble is that feminist politics can dispense with feminist identity, but the reader will not find much discussion of political tactics, political programs, the history of social movements involving women and so on. Butler's book is not primarily about analyzing the feminist political movement. Instead, she aims to argue that the very idea of a concrete feminine identity has flaws in order to convince the women's movement to move off of a concrete feminine identity. The argument is primarily conceptual, not pragmatic (although many postmodernist, post-structuralist philosophers like Butler will reject this distinction).