In the early 50's a man named Solomon Asch did an experiment that essentially proved that people in groups on average believe what the majority of the group believes, no matter how illogical. This was more than peer pressure, this was actual belief.
The experiment went like this. A person was ushered into a room along with a group of other test subjects. The other test subjects were all plants so this person was the only person actually being tested though she/he wasn't aware of this. The people in the room were shown a drawing with one line on one side and a number of lines on the other side of varying lengths. Each 'subject' in the room was asked to announce which of the lines matched the first line on the drawing. The fake subjects (all going before the real subject) announced an obvious incorrect answer. When it came to the test subject, a number of the times they announced the same answer. In some cases it was found that the subjects had done more than just go along with the crowd, they had actually believed the lines were the same length!
On the web I've seen a number of reports on the experiment like this one, this one and this one, all have varying statistics so I don't know which to trust.. however the gyst is always the same, people follow the group and sometimes for non-obvious reasons. It's interesting to see that this phenominon exists and has been proven. Now think about it on a larger scale. Think about how it influences our society and our beliefs and our values. Think for a moment how someone manuipulating the group thoughts can gain a huge amount of power. Think about the BWH fear mantras. Think about the Right Wing talking points..
Most of all, try, and try hard to think for yourself. Challenge what the group thinks once and a while, you may find that the group is wrong.