The plan of this work was born of the conviction that many of the most vehement controversies in the social sciences are now ripe for resolution. The work was first conceived more than 15 years ago; but to carry it out, careful preparation was required; the publications cited in the notes will provide some information about this. Aside from the investigative goal of securing the grounds for that conviction, I also had a didactic goal in mind, to convey to the social scientist concerned with more abstract problems, and to the advanced student, an insight into the way problems of social theory have been intertwined with those of the general theory of knowledge and of sciences apparently remote from social theory; together with that, it was also my hope to eradicate a series of deeply rooted prejudices, which stand in the way of understanding the structure and significance [Sinn] of social science research, and of its undisturbed development.