Controversy is a state of prolonged public dispute or debate, usually concerning a matter of conflicting opinion or point of view. The word was coined from the Latin controversia, as a composite of controversus – "turned in an opposite direction," from contra – "against" – and vertere – to turn, or versus (see verse), hence, "to turn against."
The most applicable or well known controversial subjects, topics or areas are politics, religion and sex. Other areas of controversy include history and philosophy. Other minor yet prominent areas of controversy are economics, science, finances, culture, education, the military, society, celebrities, organisation, the media, age, gender, and race. Controversy in matters of theology has traditionally been particularly heated, giving rise to the phrase odium theologicum. Controversial issues are held as potentially divisive in a given society, because they can lead to tension and ill will, as a result they are often taboo to be discussed in the light of company in many cultures.
Legal controversy 
For example, the Case or Controversy Clause of Article Three of the United States Constitution (Section 2, Clause 1) states that "the judicial Power shall extend ... to Controversies to which the United States shall be a Party". This clause has been deemed to impose a requirement that United States federal courts are not permitted to hear cases that do not pose an actual controversy—that is, an actual dispute between adverse parties which is capable of being resolved by the [court]. In addition to setting out the scope of the jurisdiction of the federal judiciary, it also prohibits courts from issuing advisory opinions, or from hearing cases that are either unripe, meaning that the controversy has not arisen yet, or moot, meaning that the controversy has already been resolved.
Benford's law of controversy 
Benford's law of controversy, as expressed by science fiction author Gregory Benford in 1980, states: Passion is inversely proportional to the amount of real (true) information available. In other words, the fewer facts are known to and agreed on by the participants, the more controversy there is, and the more is known the less controversy there is. Thus, for example, controversies in physics are limited to subject-areas where experiments cannot be carried out yet, whereas Benford's Law implies that controversy is inherent to politics, where communities must frequently decide on courses of action based on insufficient information.
Psychological bases of controversy 
Controversies are frequently thought to be a result of a lack of confidence on the part of the disputants - as in Benford's law of controversy. For example, in the political controversy over anthropogenic climate change that is prevalent in the United States - it has been thought that those who are opposed to the scientific consensus did so because of a lack of evidence. A study of 1540 US adults found instead that levels of scientific literacy were correlated with the strength of opinion on climate change, but not on which side of the debate that they stood.
The puzzling phenomenon of two individuals being exposed to the same evidence and being able to reach different conclusions, has been frequently explained (particularly by Daniel Kahneman) by reference to a 'bounded rationality' - that is most judgments are made by fast acting heuristics (system 1) that work well in every day situations, but are not amenable to decision making about complex subjects such as climate change. Anchoring has been particularly identified as relevant in climate change controversies  as individuals are found to be more positively inclined to believe in climate change if the outside temperature is higher, if they have been primed to think about heat, and if they are primed with higher temperatures when thinking about the future temperature increases from climate change.
In other controversies - such as that around the HPV vaccine, the same evidence seemed to license inference to radically different conclusions. Kahan et al. explained this by the cognitive biases of biased assimilation and a credibility heuristic.
Similar effects on reasoning are also seen in non-scientific controversies, for example in the gun control debate in the United States. As with other controversies, it has been suggested that exposure to empirical facts would be sufficient to resolve the debate once and for all. In computer simulations of cultural communities, beliefs were found to polarize within isolated sub-groups, based on the mistaken belief of the community's unhindered access to ground truth. Such confidence in the group to find the ground truth is explicable through the success of wisdom of the crowd based inferences, however, if there is no access to the ground truth, as there was not in this model, the method will fail.
Bayesian decision theory allows these failures of rationality to be described as part of a statistically optimized system for decision making. Experiments and computational models in multimodal integration have shown that sensory input from different senses is integrated in a statistically optimal way, in addition, it appears that the kind of inferences used to infer single sources for multiple sensory inputs uses a Bayesian inference about the causal origin of the sensory stimuli. As such, it appears neurobiologically plausible that the brain implements decision-making procedures that are close to optimal for Bayesian inference.
Brocas and Carrillo propose a model to make decisions based on noisy sensory inputs, beliefs about the state of the world are modified by Bayesian updating, and then decisions are made based on beliefs passing a threshold. They show that this model, when optimized for single-step decision making, produces belief anchoring and polarization of opinions - exactly as described in the global warming controversy context - in spite of identical evidence presented, the pre-existing beliefs (or evidence presented first) has an overwhelming effect on the beliefs formed. In addition, the preferences of the agent (the particular rewards that they value) also cause the beliefs formed to change - this explains the biased assimilation (also known as confirmation bias) shown above. This model allows the production of controversy to be seen as a consequence of a decision maker optimized for single-step decision making, rather than as a result of limited reasoning in the bounded rationality of Daniel Kahneman.
See also 
|Look up controversy in Wiktionary, the free dictionary.|
|Wikiquote has a collection of quotations related to: Controversy|
- Bayesian inference
- Dental amalgam controversy
- Pensée unique
- Recuperation (politics)
- U.S. News & World Report, Volume 117, Issues 10-17, 1994 quotation:
Perhaps that was inevitable, since abortion touches on three of the most contentious subjects in human discourse: religion, sex and politics.
- Kenneth L. Karst (1995) Law's Promise, Law's Expression p.137 quotation:
Religion, sex and politics: in my younger days, these were the subjects you weren't supposed to discuss at the dinner table.
- Susan Spencer, Margo Collins, Albert J. Rivero (2004) The eighteenth-century novel: Volume 4 p.6
...the expiration of the Printing Act in 1695 swelled the number of licensed printers, while the relaxation of censorship under the Restoration opened once-guarded topics, especially religion, sex, and politics, for public discussion
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