“It is the tension between creativity and skepticism that has produced the stunning and unexpected findings of science.”

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

How to Understand Politics: What the Humanities Can Say to Science (2007)
Context: The simplified notion of self-interest used by our political and social science cannot tolerate the tension between one’s own and the good, for that tension leaves human behavior unpredictable. One cannot penetrate into every individual’s private thoughts, and there is no clear way to judge among different conceptions of the good. So in order to overcome the tension, science tries to combine one’s own and the good in such a way as to preserve neither. It generalizes one’s own as the interest of an average or, better to say, predictable individual who lives his life quantifiably so as to make its study easier for the social scientist. And for the same purpose it vulgarizes the good by eliminating the high and the mighty in our souls (not to mention the low and vicious), transforming our aspiration to nobility and truth into personal preferences of whose value science is incognizant, to which it is indifferent.

Source: Faith vs. Fact (2015), p. 89

Attributed

Introduction to the Enlarged Edition
1940s, Foundations of Economic Analysis (1947; 1983)

The Temptation to Exist (1956)

2009, Nobel Prize acceptance speech (December 2009)
Context: There has long been a tension between those who describe themselves as realists or idealists — a tension that suggests a stark choice between the narrow pursuit of interests or an endless campaign to impose our values around the world.
I reject these choices. I believe that peace is unstable where citizens are denied the right to speak freely or worship as they please; choose their own leaders or assemble without fear. Pent-up grievances fester, and the suppression of tribal and religious identity can lead to violence. We also know that the opposite is true. Only when Europe became free did it finally find peace. America has never fought a war against a democracy, and our closest friends are governments that protect the rights of their citizens. No matter how callously defined, neither America's interests — nor the world's — are served by the denial of human aspirations.

Librarians and Information Systems (1995)

Charlie Rose: An Interview with Carl Sagan http://www.charlierose.com/guest/view/4553, May 27, 1996.
Context: Science is [... ] a way of skeptically interrogating the universe with a fine understanding of human fallibility. If we are not able to ask skeptical questions, to interrogate those who tell us that something is true, to be skeptical of those in authority, then we’re up for grabs for the next charlatan, political or religious, who comes ambling along.