Groups divide by whether inclusion or exclusion is their default principle

Evidence

We note here the distinction of two principles, which clearly indicate a basic differentiation of the sociological significance of groups generally, no matter how much practice may mix them and make the difference lose some of its sharpness. On the one hand, there is the principle of including everybody who is not explicitly excluded; and, on the other, there is the principle of excluding everybody who is not explicitly included. — Georg Simmel, The Sociology of Georg Simmel, 8903

Categorization

• DEFINE: A clean conceptual axis for classifying group boundary logic: default-inclusion vs. default-exclusion.
• XREF: Echoes the openness/closeness dialectic in Information Society readings on network boundaries.