This paper proposes an explanation in terms of three kinds of freedom, first for the special efficacy of science in general and then for why such efficacy has been more impressive in the natural than the social sciences. This explanation thus complements "post-positivist" interpretations of science which argue that science's effectiveness cannot be accounted for by fundamental epistemic differences from other kinds of discourse. My explanation tries to say what is responsible for science's effectiveness, in purely nonepistemic, sociological terms. All (...) of the three kinds of freedom have so far been denied to most other forums, including in particular nations' populations taken overall. And one of these freedoms, while now allowed to the natural sciences, is still denied to the social sciences. (shrink)