But these rules and constraints are exactly what I mean (if I got you right). I believe that really every group implies such constraints to individuals. Even the happiest and most open society in a pub has its limits. When I join, I obviously should not smell, I should not randomly insult other people because of my tourette syndrome, ... What I'm thinking is very basic and theoretical. If resources are restricted, it is even more obvious, then I have to sacrifice part of my personal profit for the sake of others or there will be conflict with the group members. That's very basic game theory. A group is an environment, and like any environment it demands adaptation. I believe that a 100% tolerant group is an oxymoron. That being said I also believe that a group can be more-or-less tolerant.
I'm not sure, it seems exaggerated to me. I'll try to dissect a bit by using some examples:
First - negative reason for self-ostracism: Self ostracism in prison has a reason (my guess is fear or awareness of threat), and I wonder if this fear is the true reason for the clinical depression. That's an open question. I don't know all details about solitary confinement, but I also believe that there is not only deprivation from social activitiy but also deprivation from any activity. I guess there are no books, no paper to write or paint, no tools to make stuff, no sports, no hobby, no distraction, poor environment in general. Perhaps that's another open question.
Second - positive reason for self-ostracism: There have been monks who have sworn to never talk a word to anybody and there have been voluntary eremites. I think the point is whether the eremites are tolerated or not. For religious reasons they certainly have been tolerated in the past. If not, then the eremite knows he is outlawed and he will suffer much more from fear than from lonelyness. In this case he is either not self-ostracised or he is exceptionally self-confident.
Third - imposed ostracism (after imposed collectivation): Take school for instance. If you are obliged to go to school everyday you are obliged to fit in, which represents a challenge. Ostracism is the attested failure to handle this challenge and promises further trouble ahead. I dare again to claim that the resulting feeling is painful not because of lonelyness but because of insight into the consequences: failure and trouble. But what if you are not forced to go to school but are tought by your parents instead? No challenge - no failure.
Fourth - ???
Indeed every group will have rules or rituals particular to that group, I am in agreement with this ElHorsto.
And I also agree with what you describe as the basic game theory. Each person in the group will know the rules [even if they find them restricting] and will have accepted them and agreed to keep by them [in general]. The pay-off, if you like, is the protection and social inclusion of the group
Some groups will be more tolerant than others, yes.
But, my aim here, is regarding the effects that being ostracised from the group, can have on a person. And the reasons why we do it, apart from punishment.
Yes, you conclude correctly. Some prisoners who use self ostracism, do it thinking it may offer a degree of safety. By becoming as invisible as possible and disconnecting themselves from any social inter-action as they can. However, in some extreme cases, some can show symptoms really quite similar to clinical depression. [When I can, I will try to post a study link]
Regarding the solitary confinement, some aspects will differ depending on the place. Are you aware of the hunger strikes and the media coverage regarding Pelican Bay Prison in California. I have a link but I cannot post it. If you do a google search ElHorsto, this is in the news at present, give it a read.
Yes, ostracism can be a positive thing. We already spoke regarding the cause for it in early societies.
The monk could be considered as a positive side of self imposed ostracism, I suppose. His reasons for doing so have not been for self preservation but rather religious dedication.
Imposed ostracism 3. But what of the student who follows the set rules, is not smelly, does not randomly offend because of his tourettes, seems as bright as his peers and shows willingness to inter-act, yet still finds himself ostracised by the larger group of buddies. Why has he been treated in this manner, how can we make sense of this, if to all purposes he is no threat to the group. Who has failed in this instance?