Two psychological views of terrorism are described, approaching it as a “syndrome” and as a “tool” respectively. Research thus far found little support for the syndrome view. The heterogeneity of terrorism's users is consistent with the tool view, affording an analysis of terrorism in terms of goal–means psychology.
Kruglanski, Arie W., and Shira Fishman. 2006. "Terrorism Between 'Syndrome' and 'Tool'." Current Directions in Psychological Science (February): 44-48. http://cdp.sagepub.com/content/15/1/45.full.pdf+html