His preference for "piecemeal social engineering" (small, reversible changes) over "utopian social engineering" (radical, wholesale societal shifts).
The criterion for distinguishing scientific statements from non-scientific ones.
The rejection of the idea that history follows predetermined laws or paths.
This was a major ideological conflict in German sociology during the 1960s. It primarily featured a confrontation "with Popper" (sa Poperom) and Hans Albert on one side (critical rationalism) against Theodor Adorno and Jürgen Habermas of the Frankfurt School (critical theory) on the other. You can find detailed academic papers on this debate through repositories like Scribd .