Professional sociology positively undertaken in the spirit of the Enlightenment imagines that knowledge can be secured on true foundations and thus serve as the basis of progressive change in society. The change takes the form of piecemeal social engineering, otherwise known as liberal reform. Those sociologies making the interpretative turn do not so much doubt that the house of knowledge has stable foundations as question just what it is that the foundations are made of. Male sociology and society, and instead of electing to separate themselves from both male theory and practice, postmodern feminism opts for transgressing the boundaries of the dual gender categories that feminism posited in the first place. Queer theory is heavily indebted to Michel Foucault, himself gay, who is regarded as the poststructuralist whose work has had the greatest effect on sociology. Michel Foucault's argument concerning homosexuality mirrors his earlier analyses of mental illness and crime.