A lot of thoughts come up for me in this topic. The loudest one at this point is that our identities are constructed out of the stories we tell ourselves, which reaches into history and therefore the entire legacy of society itself, in the myriad ways it has existed. Particular stories we tell ourselves can be empowering or disempowering, and set up expectations and customs for how we conduct ourselves and treat others. If you read the Illiad for example, you have a very different outlook on life and your position in the world than reading, say, Mark.
Humans have a diversity of moral tastebuds (a la
Jonathan Haidt's work). One of these is "Ingroup Loyalty," which causes a person to emotionally adhere to an ingroup member's case over an outgroup member's case. From the perspective of other moral tastebuds or instincts, it can be seen as irrational, but vice versa also applies). Sometimes I don't know what to make of this from an intelligent design perspective. Ideally all the DNA works together properly to accomplish a function, but due to mutations and all sorts of hybridization and genetic drift people can have conflicting moral values at times, where someone who looks very different from you can make you less empathetic toward them at first blush (purely a clinical description here, not judging it since it's an instantaneous unconscious process), yet they may have babies that have big eyes and all the other things that stimulate our "care" instinct. But the more you speak and get to know one another and share stories you and "the alien" see you have overlapping understandings of things and a shared sense of reality in some respects, so empathy and limbic resonance increases. Maybe you don't share the same metaphysics or sports team loyalties, but those are a type of difference people (in liberal societies at least) are accustomed to dealing with, and are often fully aware of how to make space for both to coexist (the old addage of never discussing religion and politics comes to mind).
Looking into the past, people tended to be very tribalistic, but the divisions more often than not were not between different racial groups, but between different groups of people who spoke different languages. And this is what we would expect, when identity is constructed out of stories mediated by languages. It doesn't matter if Achilles was an Achaean or you an Englishman. If the story is translated you can read it, and develop understanding and see into the mind of Achilles and how he thought about things. . If you could time travel you could commiserate with him about his mistreatment by Agamemnon.
This coming together in mutual understanding is the core nature and purpose of (capital S) Society, period.
Collingwood has a lot of insightful things to say on this topic of societies, which is quite relevant because in various ways he was writing in response to the political science climate of the 30's and 40's. He defines a society as a community of free agents who decide to act collectively to fulfill an Aim. We form societies and achieve understanding together to accomplish the task of living together on this planet. The problem with any racially-based consciousness is that it is a development of the loyalty moral tastebud, but of all possible developments and implementations of this tastebud, it is unnecessarily limiting. The idea of "huights" coming together to fulfill a collective interest may be a better idea than some forms of tribal collectivism (such as a gang loyalty), but still worse than others, for a number of reasons.
If you intend to ask me for the reasons, I'd need you to explain exactly what this white identity is, what its stories are, and how those stories entitle its believers to treat themselves and the others mentioned in said stories).
The nice thing about language is that you can learn these, and so other people's stories, if there is some wisdom in what is said, become your stories for empowerment. Different organizations engaged in the work have a sense of their own identity and mission, and set high standards of behavior and do some very tight policing around now allowing pathological individuals or people who lack knowledge and awareness to disrupt them. So in theory there is tight policing of a boundary and there are people closer to the margins than others (in Work terms this would be the esoteric, mesoteric, and esoteric circles). Fundamentally though such an identity is a product of our decisions as individuals to engage in the formation of a society with a particular mutual understanding of our role in the universe.
I totally agree with some of the pathological material coming out these days about how people, because of their race, are taught (or learn passively through cultural osmosis) to be discouraged, demoralized, and so on. Those stories more often than not are the product of certain traumatic holding patterns,
which we can move beyond. Nobody here feels like anybody should feel guilty or responsible for an action over which they had no control, or in any sense disempowered because of false black-and-white constructs of reality.
To exclude someone from a Society just based on their race, despite being something someone cannot control and despite being perfectly capable of contributing in some capacity to the society, is to shrink the talent pool for accomplishing the mission your society is set out to accomplish. A similar, smaller scale form of this exclusion is nepotism and cronyism in businesses. This behavior is well studied and is shown to negatively impact the performance of a given firm or corporation, for reasons that are quite obvious.
This is not to say that I think people should have no right to freely associate with whomever they want. But people have always been able to do so for less-than-rational reasons.