Dogma may be defined as established opinion, a doctrine put forth without evidence, or as a body of doctrines supported authoritatively by a church. But when you consider a combination of all three--an established opinion without evidence, supported by the authority of supernatural beliefs--you have a summation of everything that the JREF is opposed to. As it so happens, religion is the largest central distributor of dogma, but you can find it within other circles of opinion as well.
Theology is defined as "faith justified by reason." But this is another way of saying "A conclusion in search of a justification." This was the dominant philosophical approach of the dark ages, and it was this habit that kept them in the dark. Beliefs were fortified and communicated, supported only by citations of other beliefs, forming a circle of opinion with no means of objective correction. Theology remained a circle jerk, somewhat like partisan bloggers, who reinforce their mutual preconceptions by echoing them back and forth, referencing each other, accepting only what evidence confirms their beliefs and ignoring the rest (when they reference evidence at all.) This is the modus operendi of dogmatists, and it can become a prison which is difficult escape. This is what made science impossible in the dark ages, and it was only when a central dogmatic authority of the Catholic Church was shattered that science and philosophy could flourish.
This same hermetically sealed community of belief can also be found amongst political ideologues, proponents of various pseudo-sciences and occult dogmas, and amongst conspiracy theorists. Conspiracy theorists are notorious for this tendency to form communities of the deluded, for in their case the opinions they hold are often so outrageously wrong that conspiracists often appear genuinely insane. The internet has been instrumental in the rise of new conspiracy theories because it provides the opportunity to form the kind of closed, circular, and mutually reinforcing groupthink which was previously available only to close knit religious communities or tightly structured political groups. This means that conspiracists should be properly considered as a species of dogmatic believer similar to members of a religious sect.
Religious and political philosophies, however, may incorporate valid ethical and social observations, which may attract followers with different motivations, diluting the purely dogmatic elements. Consumers of pseudo-science make common cognitive mistakes which requires research to dispel; many may simply have not taken the time to know better, and may not have much at stake (those who pay thousands to psychics and faith healers are another matter). Their entertainment of nonsense may be casual and not a central feature of their personality; when the stakes are high, they go to a doctor, not a homeopath. Conspiracy theorists, on the other hand, are usually quite dedicated and quite vociferous in what they believe. But most importantly, conspiracists are barking mad--pure dogmatists. Examination of conspiracists will throw light on the nature and habits of purely dogmatic believers of all kinds.
Conspiracists share in common with other dogmatic believers the following traits:
1) Epistemological Incompetence. Conspiracists lack basic tools of comprehension concerning the way the world works. These include a poor understanding of logic, science, and human nature. They have little or no grasp of what James Flynn calls shorthand abstractions (SHA's). SHA's include the concepts of the market, percentage, natural selection, random samples, control groups, the naturalistic fallacy, the charisma effect, placebo effect, falsifiability and tautology, and the tolerance school fallacy. Some of these you may recognize by name, and I'm not going to go into a full explanation of all of them. Flynn's work is stellar. He is best known for the Flynn effect, the measured gradual rise in IQ over the last century. His conception of the SHA's is a must read; Flynn believes that the acceptance of scientific ways of thinking is responsible for the Flynn effect. You can find it
here. This is where he lists and describes the SHA's and several anti-SHA's, the latter being common misperceptions leading to false conclusions.
The important point is that these are tools needed to understand the modern world. Without them, conspiracists literally do not understand how the world works. This is the root cause of all of their other problems. The conspiracy theory not only exploits this weakness, but reinforces it. Acceptance of conspiracy theories may in the long term actually impair the ability for critical thinking. One conspiracy theory leads to another, and all seem to lead, eventually, to the moral and cognitive black hole of anti-semitism.
2) Epistemological Relativism. Since conspiracists do not understand the methods for reaching a correct conclusion, all conclusions are equal and based solely upon the weight of authority. In short, there is no truth, only opinion. It is a sad fact that someone can acquire a scientific or technical degree without ever fully understanding the scientific method. It is possible to take the results of science as received wisdom, and parrot it back successfully on exams, without understanding how it was derived. Dogmas are conclusions, cues to stop thinking, rather than means of arriving at conclusions. There are some that will learn science in this way, and never move beyond the dogmatic mindset.
3) Confirmation Bias. Conspiracists disregard arguments that refute their thesis, usually by relying on the Genetic Fallacy--the source is in on the conspiracy, and therefore cannot be trusted. There is no truth, only opinion, and only the right opinion is acceptable. The Grand Cabal "got to them", or their interests are somehow served by the conspiracy. Their motives are therefore impure, and nothing they say can be considered worthy to discredit the conspiracy theory. Since conspiracists consider all arguments to be arguments from authority, the choice is not between correct methodologies, but correct authority.
4) Selective Bias. Conspiracists emphasize only those snippets of fact that confirm their beliefs, and disregard or dismiss the bulk of evidence which refutes their thesis. A common practice is quote mining, where a single statement (or even a portion of a statement) is quoted out of context as evidence for the theory. When the original source objects to the interpretation of the quote, the conspiracists fall back on the Genetic Fallacy, claiming that the source has been compromised since the original statement. Conspiracy theories are therefore unfalsifiable.
5) Exceptionalism. Conspiracists grant their own theories exception from logical or methodological principles that they routinely apply in the rest of their lives. Occam's Razor is a good example of an abandoned principle; it is hard to believe that a qualified engineer would not be familiar with this logical tool, yet there are many engineers amongst "Truthers", whose theories concerning the events of 9/11 multiply entities on a grand scale while the real explanation is remarkably simple.
6) 'Gaps' Arguments. Rather than provide a comprehensive argument, backed by evidence, conspiracists rely on a false dichotomy, attempting to argue that there are inconsistencies in the accepted explanation, and then presenting their own as the only alternative. When these gaps are filled the conspiracists pretend not to hear the new evidence, and continue to point to gaps that have in fact been filled. Since this new information contradicts their claims, it will not appear in discussions amongst the conspiracists, and will be blithely ignored when presented by someone else. This additional information is, in their mind, intended to refute what they have already decided is true and therefore obviously ideologically based and not worthy of consideration.