How we change what others think, feel, believe and do
Groups have common purposes or interests, which they will seek. Unsurprisingly, these are similar to the interests of individuals, who may well join the group to better achieve these goals.
One of the principles of evolution is that any organism will seek to survive by any means at its disposal. Humans are different from other species in their understanding of death and extinction. Others may naturally fear it, but we conceptualize and complexify it. Yet our instinct for survival is still remarkably powerful and we will grasp at the last seconds of life.
Groups are likewise driven to survive and many of the rituals and processes have a strong purpose in sustaining the culture and continuation of the members' lives together. Groups that once had a very practical purpose persist as social organisations (for example the freemasons).
One way of surviving, particularly in a competitive world is to constantly fight for growth. When predatory tribes may decimate smaller groups, there is a distinct advantage in size.
Whilst growth allows greater goals to be achieved, growth can also become a purpose in itself. Success gets measured in the relative change in size rather than achievement of other, perhaps more socially meaningful goals.
Not all groups seek growth. Growth can bring may problems, from the need to move premises to the potential dilution of the original culture and subversion of its purpose. There is comfort in familiar faces and there can be threat in those whose truth is not yet known.
A benefit of belonging to a group is where everyone believes that the group has a higher and more noble position that others. Religious groups can be like this, taking the moral high ground and looking down on their wicked neighbors. Other status variables include money and power.
When we agree with others and care about one another, then we can achieve a state of mutual and pleasant harmony. In a harmonious group we know we can approach others without worrying about whether they will act aggressively towards us. When everyone seeks harmony, there is no threat.
Some cultures (such as Japan) place particular emphasis on this, such that harmony is a fundamental aspect of many decisions. Groups also have a tendency to seek internal harmony and can fall into a state of groupthink, where dissenters are hushed with subtle words and even threats.
Harmony supports survival but may conflict with growth. Growth implies change which can disrupt harmony. If there is a balance and effort is applied to both, then growth can be achieved more successfully.
Just as we all seek meaning in life (and it has been said that the meaning of life is to find meaning), so also do groups seek a common meaning by which they can create their identity.
Groups may be held together by pre-defined meaning, as happens with many religions. Technical groups also use meaning as a cohering principle, where systems are imbued with certain qualities and jargon is used much as a religious code.