One example of this is the failed 1975 prophecy by the Jehovah's Witnesses. Despite the complete failure of Jesus to return on that date, and despite a large amount of people leaving the movement as a result, quite a lot of people remained in the faith. Why?
Traditionally the explanation has been "cognitive dissonance", the ability of the group to keep a strong influence upon individuals within the group who are beginning to doubt. This no doubt provides some explanation.
However, in an interesting article entitled Evaporative Cooling of Group Beliefs, blogger Eliezer Yudkowsky has come up with an alternative explanation - or at least one that can fit neatly alongside cognitive dissonance.
It's a really strange idea since it takes into account the scientific process of examining how evaporative cooling works - yet it applies very well to the group situation.
Let me start off by quickly explaining how evaporative cooling works.
Basically, when a surface is covered with water (like human skin with sweat), the evaporation of this water from the surface causes it to cool down. In other words, the heating process of evaporation of something small results in the cooling of something big.
Now let's apply this to a group - say a religious cult with prophecies. Members of this group are not all equal in their adherence to the faith. Some are complete wackos, while some have the semblence of objective thinking. Altogether they represent the cult group. Now let's say that the prophecy passes without being fulfilled. What happens then? Well, all the objective, thinking group members leave, while all the wackos remain. Because the percentage of wackos in the group increases, the effect of the unfulfilled prophecy results in stronger belief amongst those who remain faithful, or at least giving the group a chance to exhibit cognitive dissonance, thus making it difficult for others to leave the group.
In other words, "heat" is applied to the group, and those who "heat up" end up leaving, while the ones left behind get "cooler".
It's a fascinating idea, and one which can also be applied to the Iraq War.
Back in 2003, the majority of Americans wanted to invade Iraq. A noisy minority protested, but the majority essentially gave Bush the impetus to invade. Years later, however, and the "heat" has been applied. The WMDs have not been found, statistical studies are now estimating the death toll at over 1 million Iraqis, and US troops are in harm's way without any real military objective except to shoot those who shoot at them.
You'd think that things like facts would change people's minds. Of course, facts have changed people's minds - just not all of them. As the majority of Americans slowly realised that the Iraq War was the wrong thing to do, they began to no longer support the war - "heat" was applied. With dwindling numbers, the pro-war side becomes even more committed to their cause - they begin to "cool" as they become smaller.
And, of course, "wackos" are less likely to use things like reasonable arguments to back up their cause. Instead they begin to use "ad hom" attacks upon their opponents, and even lie about them in order to keep their side "strong".
Interestingly, the same sort of thing is happening in the world of environmental science - specifically regarding global warming. Strangely enough it is not the global warming "believers" who are ending up being the wackos but the global warming deniers. Again, this is because of the evaporative effect. As more and more people begin to believe in the science of global warming, those who remain behind become more "wacko" in their denials and begin to "cherry pick" evidence, while at the same time accusing their opponents as being "wackos" who "cherry pick" evidence, thus exhibiting Psychological projection - seeing in other people their own faults and behaviour.
Depending upon the "faith" that these people have put their trust in, it is quite reasonable to expect that a minority of people will continually remain true to the "faith". Just as Southerners in the Civil War have been able to transfer their misguided feelings of injustice upon their descendants (who make up the Neo-Nazis and Ku Klux Klan of today), so will there be people in decades to come who will still think that the Iraq war was justified and Bush was the greatest president ever. Global warming deniers will probably change their minds in the future, but only when evidence goes against them and only if it suits them. They may say "Yes it is undeniable that the world is heating up and that millions of people have now lost their lives, and I also agree that previous attempts at explaining global warming were incorrect (that is, theories which said that is merely cyclical or based upon sunspots), but I would still argue that it is not due to CO2 based human activity but to something else yet to be determined by science."