The consequences of ideology are important because ideologically-motivated behavior often diverges from what is truthful--ideology taken to an extreme can become authoritarianism or totalitarians. Examples are Hitler, Mussolini, Stalin, Pol Pot, and the various Mid-East leaders who are the targets of the recent demonstration (some of whom exploited ideology to attain power or maintain it). One example of how ideology works is from Hamilton (2009; http://alturl.com/ifdd7): higher education among "strong" Democrats (in the U.S.) is associated with belief in higher risk in climate change, but higher education in "strong" Republicans is associated with belief in lower risk of climate change (Fig. 3). Higher self-rated knowledge of climate change follows the same, diverging results (Fig 2).
Regardless of who is correct in an ideological debate, ideology will drive a large group of people to make bad decisions while they rationalize their actions to fit their ideology. My view of the Hamilton study is that a large group of people (conservatives), without access to data and without the skills to analyze it, implicitly claim insight into vastly complex phenomena--they assume that their gut feelings are precise enough to refute scientific data and analysis. In my experience, ideologues do not admit reliance on gut feelings but instead interpret selected pieces of information using their intuition to judge how that piece of information can refute an entire body of evidence (e.g., some claims against global warming are judged as sufficient to invalidated a large body of scientific evidence without integrating that piece of information into a coherent climate prediction model). On the other side are people with little alternative then relying on reports of scientific findings as proxies for understanding truth directly (and theoretically some powerful lobby could manipulate this evidence). Many people on both sides rely on what I am calling intuitionism--belief that their intuitions lead them to truthful insights into complex realities.
In the Tea Party example (a libertarian political movement in the U.S.), a common theme is a belief in inalienable rights to liberty combined with a long list of more specific rules and principles that derive from that general rule. I see this reliance on inalienable rights as a deontological approach that both derives from intuitionism and reinforces it. In contrast, consequentialism can facilitate a more grounded approach that forces people to at least look at evidence. It is evidence that is the enemy of ideological fanaticism. (Note that I am not associating the Tea Party with right-wing authoritarianism, but the TP often employs deontology and intuitionism, which started this thread).
Here are some of my thoughts on the manifestation of ideologically-motivated behavior:
1) The vast majority of humans rely on intuition for many of the decisions that they make every day. This includes seemingly trivial things like choosing clothes to wear, and extends to other things like choosing a profession, choosing activities that might or might not adversely affect others or the environment, communicating with others via non-violent communication or violence (where intuition is at least a substantial part of the decisions).
2) Humans lack the quantitative skills to answer many of the important questions that affect their daily lives, so reliance on intuition, biological or psychological predispositions, trust, or other non-rational processes often drive behavior. In other words, I do not have all the skills needed to make scientific choices about everything I do even if there are thousands of people who each have great skill in one particular area.
3) Humans exhibit a variety of cognitive biases that lead them to accumulate beliefs that are consistent with (a) their predispositions and (b) their existing beliefs. Examples are belief bias, selective exposure to information, selective scrutiny, selective recall, and appeal to Moorean facts. In other words, we distort our exposure to and interpretation of knowledge to suit what we already believe (Google 'cognitive bias').
4) Humans exhibit individual differences in psychological characteristics that reflect differences in motivations for behavior (e.g., aggression, need for power, need for security, openness to new experience, neuroticism, empathic concern, egoistic concern—often phrased as differences in personality or values). Clusters of these differences are associated with ideological stances (Adorno et al., 1950; Mavor, Louis, & Sibley, 2010; Schwartz, 1992, 1994; Schwartz & Bilsky, 1990).
5) Other: social influences of parents, peers, culture, subculture, and advertising.
The process: humans in different ideological groups might begin life with approximately equal philosophical short-comings (items 1-3 above), but their psychological dispositions take them in different directions. Some people feel aggression, a need for power, a need for people to be submit to authority, and these traits are clustered on the opposite side of a dimension for openness to new experience, beneficence, and similar traits that I correlate with empathic concern (see Schwartz, 1992, 1994; Schwartz & Bilsky, 1990; Mavor et al., 2010). Individual differences in empathic concern (especially when the opposite end of the dimension is need for power and authority) reflects a fundamental (implicit?) philosophy: empathy is a connection with others while need for power is (implicitly) opposition to others (others must obey authority). Various cognitive biases lead people to strengthen their ideological stance, with some people having motivation to continue to develop the ideology.
The empathic disposition (a disposition to have empathy or otherwise care for others or the environment) would seem to lead to consideration of evidence of how others are affected by action, and the authoritarian approach would (philosophically) seem less attached to the need for evidence. A person who, perhaps implicitly, adopts an intuitionist approach and also has the personality trait-cluster of strong conservatism or authoritarianism could easily associate their need for power with an ultimate truth. In other words, intuitionist are inclined to believe that ideas in their heads are ultimately correct despite lack of (legitimate) evidence, and if biological, psychological, and social forces lead people to feel a need for power and obedience, then they will be inclined to think that this is the correct way for the universe to be (once again, without feeling a need to assess evidence to confirm the beliefs). To the deontological/intuitionist/ideological conservative, people who oppose the acquisition of power are not to be considered as negative utility, but are instead to be considered obstacles to the higher need (which is power). When a higher need (power, or maybe even liberty) is held above the need to assess consequences according to how living organisms are affected, ideological tragedy can follow.
(Note that ideology can also lead to the opposite extremism, as in eco-defense terrorism, but this has historically been less prevalent and has resulted in less loss of life than totalitarianism or authoritarianism. Perhaps the different observed prevalence of the two supports my speculation about the links between deontology, intuitionism, and right-wing authoritarianism).
Adorno, T. W., Frenkel-Brunswik, E., Levinson, D. J., Betty Aron, R. N. S. with, Hertz-Levinson, M., & Morrow, W. (1950). The authoritarian personality (Vol. 1). New York, NY: Science Editions.
Mavor, K. I., Louis, W. R., & Sibley, C. G. (2010). A bias-corrected exploratory and confirmatory factor analysis of right-wing authoritarianism: Support for a three-factor structure. Personality and Individual Differences, 48, 28–33. DOI: 10.1016/j.paid.2009.08.006
Schwartz, S. H. (1992). Universals in the content and structure of values: Theoretical advances and empirical tests in 20 countries. In M. P. Zanna (Ed.), Advances in experimental social psychology (Vol. 25, pp. 1–62). San Diego: Academic Press.
Schwartz, S. H. (1994). Are there universal aspects in the structure and contents of human values? Journal of Social Issues, 50(4), 19–45.
Schwartz, S. H., & Bilsky, W. (1990). Toward a theory of the universal content and structure of values: Extensions and cross-cultural replications. Journal of Personality and Social Psychology, 58(5), 878–891.