In general, human beings readily commit to factions and then engage in very predictable behavior: they regard their own factions as right, good and truthful while casting opposing factions as wrong, evil and deceitful. While the best known factions tend to be political or religious, people can form factions around almost anything, ranging from sports teams to video game consoles.
While there can be rational reasons to form and support a faction, factionalism tends to be fed and watered by cognitive biases and fallacies. The core cognitive bias of factionalism is what is commonly known as in group bias. This is the psychology tendency to easily form negative views of those outside of the faction. For example, Democrats often regard Republicans in negative terms, casting them as uncaring, sexist, racist and fixated on money. In turn, Republcians typically look at Democrats in negative terms and regard them as fixated on abortion, obsessed with race, eager to take from the rich, and desiring to punish success. This obviously occurs outside of politics as well, with competing religious groups regarding each other as heretics or infidels. It even extends to games and sports, as the battle of #gamergate serving as a nice illustration.
The flip side of this bias is that members of a faction regard their fellows and themselves in a positive light and are thus inclined to attribute to themselves positive qualities. For example, Democrats see themselves as caring about the environment and being concerned about social good. As another example, Tea Party folks cast themselves as true Americans who get what the founding fathers really meant.
This bias is often expressed in terms of and fuelled by stereotypes. For example, critics of the sexist aspects of gaming will make use of the worst stereotypes of male gamers (dateless, pale misogynists who spew their rage around a mouthful of Cheetos). As another example, Democrats will sometimes cast the rich as being uncaring and out of touch plutocrats. These stereotypes are sometimes taken the extreme of demonizing: presenting the other faction members as not merely wrong or bad but evil to the extreme.
Such stereotypes are easy to accept and many are based on another bias, known as a fundamental attribution error. This is a psychological tendency to fail to realize that the behavior of other people is as much limited by circumstances as our behavior would be if we were in their shoes. For example, a person who was born into a well off family and enjoyed many advantages in life might fail to realize the challenges faced by people who were not so lucky in their birth. Because of this, she might demonize those who are unsuccessful and attribute their failure to pure laziness.
Factionalism is also strengthened by various common fallacies. The most obvious of these is the appeal to group identity. This fallacy occurs when a person accepts her pride in being in a group as evidence that a claim is true. Roughly put, a person believes it because her faction accepts it as true. The claim might actually be true, the mistake is that the basis of the belief is not rational. For example, a devoted environmentalist might believe in climate change because of her membership in that faction rather than on the basis of evidence (which actually does show that climate change is occurring). This method of belief “protects” group members from evidence and arguments because such beliefs are based on group identity rather than evidence and arguments. While a person can overcome this fallacy, faction-based beliefs tend to only change when the faction changes or if the person leaves the faction.
The above-mentioned biases also tend to lean people towards fallacious reasoning. The negative biases tend to motivate people to accept straw man reasoning, which is when a when a person simply ignores a person’s actual position and substitutes a distorted, exaggerated or misrepresented version of that position. Politicians routinely make straw men out of the views they oppose and their faction members typically embrace these. The negative biases also make ad hominem fallacies common. An ad homimen is a general category of fallacies in which a claim or argument is rejected on the basis of some irrelevant fact about the author of or the person presenting the claim or argument. Typically, this fallacy involves two steps. First, an attack against the character of person making the claim, her circumstances, or her actions is made (or the character, circumstances, or actions of the person reporting the claim). Second, this attack is taken to be evidence against the claim or argument the person in question is making (or presenting). For example, opponents of a feminist critic of gaming might reject her claims by claiming that she is only engaged in the criticism so as to become famous and make money. While it might be true that she is doing just that, this does not disprove her claims. The guilt by association fallacy, in which a person rejects a claim simply because it is pointed out that people she dislikes accept the claim, both arises from and contributes to factionalism.
The negative views and stereotypes are also often fed by fallacies that involve poor generalizations. One is misleading vividness, a fallacy in which a very small number of particularly dramatic events are taken to outweigh a significant amount of statistical evidence. For example, a person in a faction holding that gamers are violent misogynists might point to the recent death threats against a famous critic of sexism in games as evidence that most gamers are violent misogynists. Misleading vividness is, of course, closely related to hasty generalization, a fallacy in which a person draws a conclusion about a population based on a sample that is not large enough to justify that conclusion. For example, a Democrat might believe that all corporations are bad based on the behavior of BP and Wal-Mart. Biased generalizations also occur, which is a fallacy that is committed when a person draws a conclusion about a population based on a sample that is biased or prejudiced in some manner. This tends to be fed by the confirmation bias—the tendency people have to seek and accept evidence for their view while avoiding or ignoring evidence against their view. For example, a person might hold that his view that the poor want free stuff for nothing from visits to web sites that feature Youtube videos selected to show poor people expressing that view.
The positive biases also contribute to fallacious reasoning, often taking the form of a positive ad hominem. A positive ad hominem occurs when a claim is accepted on the basis of some irrelevant fact about the author or person presenting the claim or argument. Typically, this fallacy involves two steps. First, something positive (but irrelevant) about the character of person making the claim, her circumstances, or her actions is made. Second, this is taken to be evidence for the claim in question. For example, a Democrat might accept what Bill Clinton says as being true, just because he really likes Bill.
Nor surprisingly, factionalism is also supported by faction variations on appeals to belief (it is true/right because my faction believes it is so), appeal to common practice (it is right because my faction does it), and appeal to tradition (it is right because my faction has “always done this”).
Factionalism is both fed by and contributes to such biases and poor reasoning. This is not to say that group membership is a bad thing, just that it is wise to be on guard against the corrupting influence of factionalism.