Why do so many people persist on using classifications with no bases in reality whatsoever?

Question

E.g. the borders of countries:

They are formed by arbitrary "rules": Sometimes rivers and coasts, but mostly due wars and other weird, historical stuff that doesn't really exist in a reality outside of the ideological concept of our imagined self-importance (at least they seem so to me: Nothing in reality ever stops at a border from one country to another, let it be disease or just animals walking around or mountains going through or...). They do not have any basis in reality (contrair to concepts like "humid" and "arid"), they do not give any more value than a more-or-less-random guess, and still, people, all around the world, persist on using these "systems" to "measure" things (e.g. racism, xenophobia, but also "the [xyz-land] culture").

Why is that so? Why do humans create arbitrary systems with no basis in reality just to use these systems do to things with it that again have no better chance in succeeding than random chance (as you might have witnessed yourself if anyone talks about foreigners being stupid, lazy and so on or people belonging to the "race" x being ... and people belonging to the "race" y being totally different).

I really don't quite get that.

Answer 1

They do not have any basis in reality

Sometimes, acting as if there is a distinction creates the distinction. If you've ever contrasted your average Frenchman to your average German, you'll see that there exists a very strong distinction. Minds have the ability to create distinctions where previously there was none. They essentially create worlds, in which the rules they create seem arbitrary but nonetheless manifest as 'real'—especially over time when momentum builds up.

Above and beyond artificial distinctions, we don't always know what distinctions to make when doing science. So we try things, until the distinction shows promise of being a natural kind. Sometimes it takes a while to find a natural kind, so people flounder around trying various distinctions and living by them even if they are baloney. It can take a lot of searching to discover true laws of nature/mind.

Answer 2

The Psychology/Sociology of Fear and Survival

To me this question is less about physical reality (why is a line drawn here?), and more about human psychology and the sociology that emerges from day to day living, which creates a perceived necessity for lines.

With foundations in Darwin and Maslow, there is broad consensus that human's worry innately about their survival and their membership in a group, and the fear of not surviving and/or not belonging has led, over time, to the creation of artificial boundaries. Inevitibly, these become physical ones: fences, walls, even fortified neutral zones (aka DMZ's). Less physical, but none the less real: cliques, classes, castes, nations, etc.

You are right that the boundaries often lack a practical basis, other than creating virtual containers for a tribe or culture to develop an identity.

The example by @labreur re: French/German differences reinforces this.

But to me, it's not that the borders lack physical cause. That is true. Beneath your question is an important implication: that the human psyche, compounded by complex interaction with other humans, creates virtual boundaries that emerge into a variety of emotional, social, and (shall we confess?) political realities. I believe these are the forces that form the basis of culture, nationalism, and sociology more generally.