Professor Sheila Jasanoff, the Pforzheimer Professor of Science and Technology Studies at the Harvard Kennedy School, delivers the Gifford Lecture entitled "Cosmopolitan Visions: Science and Reason in a World of Difference". Recorded on Thursday 3 March 2016 at the University of Edinburgh's Playfair Library. Lecture abstract: The Enlightenment ideal of humanity united in a common vision of the good, based on growing scientific knowledge and understanding, lies in tatters. Around the world, some deny evidence that we are changing the climate to our peril, that chemicals and genetic modification may threaten biodiversity, that research on pathogens could pose pandemic risks, and even that human beings evolved from earlier forms of life. These disagreements have prompted others to suggest that the fault lies in our own imperfect brains, and that human minds are incapable of grasping knowledge that seems new, unfamiliar, or fearful. What these arguments and counterarguments overlook is that science’s role in public life is not simply to provide facts and truths but to help create meaning. The facts of science have to make sense in lived contexts in order for them to carry moral weight, as truths to live by. Reason, not science, is the vehicle through which communities around the world seek to integrate knowledge and values, and societies differ in the ways they judge what counts as good reason. Shifting our attention from science to reason in public debates might allow us to break through recent stalemates, enabling productive cosmopolitanism in place of stale debates about facts and counter-facts. Drawing on the history of science studies in Edinburgh, I will argue that we are due for a second Enlightenment, one that respects ethical difference while embracing knowledge and truth.