Rawlsian idea of public reason refers to the boundaries on political justification of coercive laws and public policies that have wide impact on lives of citizens. The boundaries of public reason means that political justification should be based on reasons we can expect every citizen can reasonably accept independently of any comprehensive religious, philosophical or moral doctrine to which she adhere. In modern liberal democracies characterized by reasonable pluralism of comprehensive doctrines it is unjustified for political argumentation to be based (...) on claims that many citizens can not accept. As I understand it, the point of idea of public reason is to strengthen the relationship of civic trust or civic friendship that can ensure inherent stability of just political regime. An important part of the idea of public reason is how it incorporates scientific claims in political argumentation. Rawls writes that citizens are to base their public justification on „presently accepted general beliefs and forms of reasoning found in common sense, and the methods and conclusions of science when those are not controversial.“ If the idea of public reason is the source of political stability it is necessary to answer what it means that conclusions of science are controversial in political and social context? First, scientific controversy is different from controversy of comprehensive doctrines. Science stands outside of comprehensive doctrines so conclusions of science will not be controversial because they clash with comprehensive beliefs, but they will be controversial if they rely on comprehensive beliefs. Second, if conclusions of science are controversial within scientific community, if there are some expert witness disputing its validity, then maybe value-judgments can enter to set standards for certification of the scientific claim. If potential consequences of scientific claim are bad for welfare of some group in society than standards of evidence that will certify this claim must go up. Finally, even if some scientific claim has been certified it still can be controversial as a premise in political justification. The reason can be that certification has not been transparent and many citizens do not realize that this claim is part of scientific consensus. Again, the criterion for controversy of scientific conclusions in political context is connected to the notion of trust and not to the validity of scientific claim or supportive evidence by itself. (shrink)