Post normal science and rationality of scientific work: the study of the role of values in "post normal age"

In 20th century, a large part of science became a strategic tool for policy action. increasing Public trust in science created an expectation for providing adequate responses to global (or local) problems, such as environmental crises, pandemics, and... Normal Science, as Thomas Kuhn described, do not seems to be able to solve the problems.“Post Normal Science"(PNS) refers to a new puzzle solving system in which Global problems i.e.the problems with high uncertainty, disputed values, high stakeholders, and urgent decision-making are discussed. The quality of scientific activities in post normal science is assured by an extended peer community, i.e. a large community which consists of not only local scientific experts, but also publics and the experts in different scientific areas. The claim is that in post normal science the relationship between fact and value is reversed, and it is facts that changed in accord with values.In the paper, by describing post normal science and analyzing the concept, it will be argued that the boundary between normal science and post normal science, can be clarified by decrease in interest in activities based on instrumental rationality i.e. the rationality in which the logic of science is working as a means for achieving to a pre-determined purpose. the proposed alternative to instrumental rationality is the one in which the goal of science will be achieved through a procedure based on public understanding.