Groups, Tribes, Systems, and Broken Systems
Here's a quick overview of terms, so we're all operating on the same playing field. Some of these terms are actual sociological terms; others are more informally worded ones that I've adopted to make it easier to engage with a very complicated subject.
A group is, well, any established, formally or informally defined, coherent group of people. Usually the people in the group identify as being part of that group. The body of Christians universal is a group, and so is the Southern Baptist Convention (SBC), and so is the local little bitty sorta-Baptist nondenominational church, and so is the choir of that little bitty church. People can belong to lots of different groups at once, and can switch between their self-conceptions constantly. In some contexts they'll be "members of their school's graduating class;" in others they'll think of themselves more as "workers of this certain company;" in still others they'll present themselves as "citizens of this country/state they live in."
A tribe is a group that's taken their group affiliation way too far and begun doing harmful and unpleasant things to everyone possible--both in and out of the group. They consider their group superior to all other groups, thereby considering everyone outside the group inferior (or worse, maybe not even fully human). Members of tribes usually put their membership in that particular group above all of their other affiliations, and advance their group's system before even considering doing so for the other groups they might belong to. Abusive behavior abounds here, both toward lower-ranking members of their own tribe and toward non-tribemates.
A system is a group's ideology, tactics, and recommended behaviors that the group's leaders expect members to follow. That system could be a weight-loss or bodybuilding regimen, a political worldview that members must agree with, or a recommended type of activism. Some systems are way more demanding than others; tribes often establish systems that isolate members from non-members and severely punish dissent of any kind.
The system is supposed to help achieve the group's stated goal, which might take the form of a formal mission statement or catchphrase. When someone asks the group's members what they're trying to accomplish through their group's system, their immediate response will take the form of their group's stated goal.
If the system creates way more harm than good and results in heartbreak more often than fulfillment, if it creates and feeds hunger for power, and particularly if the system shields abusers and predators, thereby making it way easier for such people to find and exploit victims, then that system is broken, which makes the group dysfunctional. A dysfunctional group produces drama and conflict for everyone who comes into contact with it.
Often a dysfunctional group will have a second set of goals that are totally unstated. When their system doesn't match their stated goal, look instead to see what it's producing. That actual result is going to be the group's unstated goal. That unstated goal isn't normally very pretty, which is why the group keeps it on the down-low.
Science NetLinks: Lesson plan for learning about groups.
The Atlantic: Discussion about the term "tribal."
Neat Article: People prefer belonging to groups that can punish "freeloaders."