During Andrew Selee's interview with Milton Friesen, he explains the appeal of think tanks:
You work with people ... to think not just, "What does legislation need to look like?" or "What is the best kind of program that should be enacted?" but actually, "What are the assumptions about how we see the world that then will affect what we think should be done?" It's less immediate but it's ultimately powerful because it can change the direction of where the world goes on a specific issue.
Listen to the rest of their conversation: