Policy decisions of democratic government are subject to an imperative of justification. This claim is not only the hallmark of liberal and deliberative political theory, but arguably also underpins the argumentative turn in policy studies. At the same time, this turn has entailed a conception of political judgement as an essentially practical activity. Policy decisions are taken in inherently unstable environments. By implication, their rationality cannot be reduced to the application of theoretical knowledge. This raises the question of where the practice of democratic policy making finds the stability that its justification necessarily demands. The paper argues that one such source of stability are scientifically generated theories. Rather than providing a method for the unambiguous identification of political truths, science is seen here as a social context specialized in investing its semantic offer with a relatively high degree of coherence, thanks to which scientific argumentations are attractive foundations for the justification of policy decisions. Insofar as justification is a necessary condition of persuasive policy making in a democracy, it weds to the notion of policy rhetoric elements of a prototypically scientific rationality. The rhetorical attraction of scientific arguments is, however, premised on a homology of the evaluative standards that define modes of democratic justification and basic varieties of scientific theory. In other words, the persuasive potential of scientific theories is selective (rhetorically not neutral) and rooted in their own axioms. For the study of the respective affinities the paper proposes an analytic taxonomy and commensurate interpretative research strategy, which is illustrated with material from a case study on employment policy making.
