According to Wilfred Bion
We are now in a better position to define the ‘good group spirit’ that has been our aim. It is as hard to define as is the concept of good health in an individual, but some of its qualities appear to be associated with:
1) A common purpose, whether that be overcoming an enemy or defending and fostering an ideal or a creative construction in the field of social relationships or in physical amenities.
2) Common recognition by members of the group of the ‘boundaries’ of the group and their position and function in relation to those larger units or groups.
3) The capacity to absorb new members and to lose members without fear of losing group individuality – i.e. ‘group character’ must be flexible.
4) Freedom from internal subgroups having rigid (i.e. exclusive) boundaries. If a subgroup is present, it must not be centred on any of its members nor on itself – treating other members of the main group as if they did not belong within the main group barrier – and the value of the subgroup to the function of the main group must be generally recognized.
5) Each individual member is valued for his contribution to the group and has free movement within it, his freedom of locomotion being limited only by the generally accepted conditions devised and imposed by the group.
6) The group must have the capacity to face discontent within the group and must have means to cope with discontent.
7) The minimum size of the group is three. Two members have personal relationships; with three or more, there is a change of quality (interpersonal relationship).
Excerpt from W. R. Bion’s Experiences in Groups, 1961.