Research literature on causational factors and diverse goals that drives people to resort to carry out terrorist acts is inconclusive. How these two are connected can be a matter of debate: are researched causes derived from terrorists' manifestos, implicitly or explicitly worded goals, or are living conditions perceived as unjust and not decent and therefore its goals may be inferred, or a mere conjecture? Multiple reasons are listed here, of which some seem to be more applicable than others, and some others tend to go together for identification of more or less convincing causational factors.
Probably the most contested cause of terrorism is an aggrieved group resorting to violence for nationalist or separatist reasons; depending on one's point of view, this can be considered as resistance against an (external) oppressor. Thus far, only Mahatma Gandhi and his followers of the freedom movement have managed to liberate themselves from foreign occupation by peaceful means (Freewoman, 2001), whereas in most other (previously) colonized states "nationalism movements commonly turned to terrorism", it being "the resort of an extremist faction of this broader movement" within an ethnic minority (Crenshaw, 1981:383). Williams (1994) provides an overview on the relation between ethnic minorities and the likelihood of conflict, for example to establish or assert language rights, religious beliefs and symbols (1994:59), but he also includes factors like "civil and political rights and privileges, ..., regional-ethnic parity in the economy... What then generates perceptions of unfairness is competition/rivalry when an ethnic is subordinated or disadvantaged in economic opportunity, social status, political voice and rights, or cultural expressions." (Williams, 1994:59) However, the cited factors are not unique for ethnic minorities. To generalize it further, ethnic conflict arises from a "complex combination" of class, inequality, political opportunity, mobilization resources and "ethnic strength" (Williams, 1994:49). How can 'ethnic strength' be measured, and to what extend is ethnicity (and related nationalist separatist movements) a constructed concept? (Nevertheless, the idea works for mobilizing people). One note of caution on the importance of ethnic conflict is appropriate. Fear on and Latin (1996) assessed the ratio of actual versus potential communal violence in Africa from independence through 1979, ranging from 0.0005 for actual ethnic violence to 0.0028 (or 0.28%) for ethnic civil war, thereby claiming that incidence of ethnic conflict is hugely overestimated due to research bias. Worded more positively: most ethnic groups live in peace with each other.
Poverty and economic disadvantage, globalization
A more important factor may be the social stratification Williams is referring to and inequalities in the distribution of scarce resources. Extensive contemporary media and literature simplify this to the poverty argument (e.g. Murphy (2001) and Kristi (2002)): when a group is absolutely or relatively deprived they rebel. A comprehensive evaluation of the extant literature on the validity of this argument, the Economic Inequality - Political Conflict (EI-PC) hypothesis, has been carried out by Lichgate (1989), who came to the conclusion that "EI-PC studies have produced an equivocal answer about the EI-PC nexus" (p440) regardless the research angle (statistics, rational actor and deprived actor paradigms). Problems Lichgate identified were notions on the lack of exactly defined economic factors influencing the decision to resort to political conflict and the "tolerance for inequality" (p452), according to the Rational Actor (RA) approach shifting to behavioral dissent only when absolute poverty is present, the Deprived Actor (DA) scientific research program's undefined additional "intermediate psychological processes" (p459), and another...