Harvard University's John F. Kennedy School of Government published a new study in 2008 that discredited the then current idea that terrorists are rational people who weigh the effectiveness of alternative modes of protest or persuasion and choose terrorism because the other options are undervalued in light of costs and goal effectiveness. It is this paradigm model placing individual psychology (cognition + affect) in the forefront of motive analysis that led to the policy of "no concessions."
The Harvard study points out that this paradigm and its policy conclusions had never previously been studied. Harvard is now positing that the motive for terrorists is strongly tied in with sociological factors such that terrorists use terrorism to advance ties among terrorists. This new paradigm states that terrorists are rational people motivated by sociological factors that enhance, strengthen, perhaps even broaden terrorist group ties.