I've thought of a perspective that works for me, and might work for others here - the way I see it, it explains a lot in human history, though it is a teleological theory (i.e. everything is seen as moving towards an aim), and so metaphysics sort of need to be constructed along the way, but a cross between Darwinism and Will to Power as first philosophy exists in this.
All existing life works towards its own survival, enhancement and expansion. Living beings do this by breeding, to be sure to pass on their own genes - instincts have their roots in chemical processes, which are determined by genes, and of course animals are made of their forms (form = bodily incarnation), which is determined by genes - passing on more than 100% of one's genes by breeding and creating more than three offspring provides 150% of your genes are passed on.
This is also a root for altruism - helping those who are genetically related to yourself - and so you're more likely to die for one of your children than you are one of your cousins, and so it seems this provides a rather loose foundation for European Nationalism, except for the excellect addition that humans aren't simply built on genes, but values as well.
Values are defined as things that people love, people cherish, people believe in. People create their own values, and a culture is a social group sharing common values and identity. Values within a culture are built by the cultural aristocracy (core element in my personal philosophy), which produces art, literature, science and philosophical beliefs that provides the identity and helps define the general spirit of the cultural group. Culture is always founded on a genetically similar group because otherwise, for the abovementioned reasons (individual pursuit of genetic immoratality, rules out any long term stability in a multiracial society), and is defined by a cultural aristocracy. Which is sort of what we're doing here.
The human person is made of two things - his values and his form (body) - both of which can be transferred from generation to generation, the values through communication and shared experiences, the body through offspring and breeding. Rationalism positions subjective consciousness as a super-special thing, but as all humans have it, and possibly animals too, the idea of free will isn't such an awesome thing as some people think and subjective consciousness isn't the greatest either - personal identity is built on form and values, and values are formed through social and individual experience and thought.
Humans can willingly compromise with each other on issues and values provided they share the same core beliefs - and this, I suggest, is Culture, in the Spenglerian sense. A Frenchman can compromise with an Englishman, a German can compromise with an (unculture distorted) American, while it is more difficult by far for a German to compromise with a Chinaman or an Englishman to compromise with an Arab.
Nationalism is built on more than just blood, it is built on culture too - and a European Nationalism demands a European culture, which has always existed. Looking into yourself and finding out who you are is a rewarding experience - the core idea is to never compromise on the basic identity on which all else is built on, to ensure that at least those values, along with one's own genes, are passed on. Survival, enhancement and expansion towards immortality in this modern world cannot exist, for white European man, without the European Nation as the core ideal - the European Nation covers his genes and his values absolutely, and subjective consciousness is temporary. For the European culture is what we are built out of, it is our foundations of who we are - "stay true to yourself" has quite possibly never had such a deep meaning.
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