Abstract: Modern public administration,grounded in scientific rationality,has developed a technology-centered governance paradigm based on specialized expertise and expert dominance.However,the recent emergence of increasingly complex and controversial technological risk issues reveals that scientific uncertainty remains pervasive.This uncertainty highlights the limitations of scientific rationality,which may undermine or even dissolve the rational foundation of public administration,thereby creating a knowledge dilemma in practices reliant on scientific rationality.In contexts of scientific uncertainty,issues such as administrative officials' ignorance and "organized irresponsibility",along with declining public trust in experts and government,may precipitate a serious legitimacy crisis in public administration.Nevertheless,the recognition of scientific uncertainty also offers new opportunities for reconstructing the rationality of public administration.Critical reflection on scientific rationality has given rise to new scientific paradigms and knowledge production models,such as post-normal science and the democratization of science.Accordingly,public administration under scientific uncertainty should evolve toward a new model of democratic administration based on "knowledge democracy",reconciling scientific rationality with democratic values to achieve rational reconstruction and paradigm transformation.

Key words: science, scientific uncertainty, scientific rationality, public administration, knowledge dilemma, technology-centered governance