"Us Versus Them."
Identifying in groups, thinking one's group good, regarding others suspiciously, prepared for hostility. A problem in this day and age? Simplistic thinking? More like natural. More like tribal, like a blood deep animal instinct. The territorial/extended familial instinct. The instinct of loyalty for and protectiveness of one's tribe. It's actually not even a problem!
The problem is when it's misapplied. The problem is when you do not know your tribe. Racism. Nationalism. These are expressions of a false tribal loyalty.
Nationalism teaches us to grossly distend and misapply the strongly felt loyalties that homo sapiens felt for tribe, extended families, for people one knew and with whom we worked in intimate cooperation: to carve out a niche for survival, to live and thrive within the bounds of our known world.
The known world was a small place, then - a garden. Hundreds of thousands of years of this living bred into us the value of such strongly-felt loyalties. Bonds of automatic trust for the members of one's positive bias group. It bred into us a concomitant wariness of, often hostility towards any out-groups one came in contact with. Naturally. Contact then often meant conflict, but usually at least competition. Us versus them was not only perfectly natural, it made good sense.
Still is. Still does. The problem is you, if you think your tribe encompasses millions of strangers. The problem is you do not know your tribe.
When writing began to make words that could stay, words that could fly, bridge long distances, bring news and values, it acquired power to unite vast stretches of land in culture, in civilization. Shared language accompanied conquest. Shared language was itself conquest. Soon, members of wide territories were exhorting each other to stretch and extend natural feelings of tribal loyalty to one's "countrymen." Bonds that had grown from shared experience in shared land, that were felt towards the families and people one actually knew, were now being stretched and distended beyond all sense. Likewise the out-group bias, the sensible wariness and preparedness for hostility towards any outsiders who actually showed up in our land - this too was perverted and misapplied.
Hordes of people we didn't know and had never met were to be treated as if they were our tribe. Hordes of other people we didn't know and had never met were to be marked out for hatred sight-unseen. We were to be prepared to war upon them.
This false tribal bias is powerful indeed. War used to be a fairly local phenomenon, but as media united wider and wider areas under culture it couldn't stay such. Once local tribes, clans and families began to ally themselves into nations, there proved to be no stopping them. Any territories occupied by tribes that had not so united their strength would be conquered by the nations that had. Disunited tribes would be swept aside, their territory divvied up and annexed. The tribes themselves could flee to further territories - a temporary solution at best, as war and conquest would not stop. Tribes that refused to flee would fare no better: conquered, subjugated, enslaved or assimilated - solutions considerably more final.
Racism is very like nationalism. Please note by "racism" I mean here race-based bigotry, such that anyone might feel. Any one of any race can have a race-based bias. Even though there are other far more complex definitions, additional senses invented to convey other ideas, the irreducible core of racism is race-based bigotry. As with nationalism, the positive group bias - the part where we are to treat millions of strangers as if we love them - is perhaps not so bad! We wouldn't call it racism if positive bias towards the in-group were the extent of it, we'd call it racial pride. For nationalism, if positive bias towards the in-group were its extent, we'd call it patriotism. Our high regard for a stranger based on some grouping we share with them may prove misguided, but as long as we are giving them the benefit of our ignorance and not the detriment of it, we don't call it bigotry even though it is bias. Positive bias, we don't call bad.
It is when we teach ourselves to regard millions of strangers we don't know as if their group makes them bad that we call bias bad. We call it prejudice, to treat or regard people as bad when we don't know who they are. When we know only one limited aspect of what they are, when we judge the person bad because of how we view their group - we call that bigotry.
Tribal bias was perfectly good, healthy and natural. Working on the scale of the local, of those one knows, tribal bias was kept in check by human encounter and real experience. As neighboring tribes came into contact, initial distrust would lead to clashes. But assuming neither tribe was strong enough to drive the other out, continued sharing of the same territory would breed a distaste for misery - ours and theirs. As we each evolved little accommodations to reduce conflict, our efforts would erode the initial cautious (and mostly beneficial) distrust. Otherness would be supplanted by acquaintance. True cooperation would spring from mutual benefit to be gained in trade, in exchange of knowledge, and soon enough, exchange of mates. Over hundreds of years of such contact and exchange, tribes become tribe - enriched and strengthened.
Nationalism and racism are based on false tribe, but the feelings they give rise to are powerful and real. When huge group divisions encompassing millions of strangers are used to bring down one's hate and contempt upon the other side - also comprised of millions of strangers - the check of personal encounter and cooperation is nowhere to be found. Distance breeds demons. Worse, the demon bred at a distance will be treated as one, once you meet it in person. False tribal loyalty is real enough to take lives, to make wars, and to set in place blood debts of hatred that - without the check of intimate cooperation and encounter to temper it and teach each group that the other is as human as we are - will endure down the centuries: an inheritance of hate.
Us vs. Them. It's natural. A survival mechanism. It's never going to go away. Grouping together and aligning in solidarity is too powerful, is too beneficial. We will not do away with it, and nor should we. Tribal loyalty remains a good and useful thing, limited to what tribe always was: those who we actually live among, encounter and experience. Then as now, it's sensible to be cautious of those whose ways we don't know. Then as now, it's sensible, understandable and human to affiliate strongly with those whose ways we do. All of this is nothing to fight.
What we must be on guard against is not bias, and not even negative bias, but ignorant bias. In a global age, people group along increasingly vast lines, and we're not going to stop this powerful alignment from happening. But we can prevent our own thinking to be contaminated with irrational distortions and false loyalties. We can keep our loyalties based in life experience, at our own human scale. It's insane, inhuman, to consider our tribe to be a group that includes millions of strangers. It's ignorant and diabolical to decide there are millions of other strangers we're not prepared to regard, encounter, or experience as equal in human dignity to ourselves. It is when we let our loyalties be ruled by abstractions that we allow strangers to be branded enemies, all based on the dictates of a false tribe. We make demons of others in our own minds, and we stand ready to do worse: to be demons ourselves. To treat the other inhumanly, if ever we should meet. All because you we do not know our tribe.
Know your tribe. If you don't know your tribe, you don't have a tribe. If your tribe includes millions of strangers - you don't have a tribe.
Humanity is not your tribe. You do not know them. Media has made it possible for you to know, and live, and love, and be in communion with - so many humans, a great deal farther-flung from you than was ever possible in past times! But possibility is not life. Life is human-scale. Life is not made of abstract people.
If you do not know the person, if you do not live in their life and they in yours, if you do not love them and share their love, whatever some media connection could somehow possibly let you be to each other gives no power, makes no connection, makes no difference. You don't know them.
Who do you know? Work with? Live with? Love? Who are you in communion with? Who is your community?
These are the people you know. These are the people it is natural for you to be biased towards. It is even good! You know them, and they know you. You love what is good in them - and love always makes bias. These people are your in-group. They are your tribe. It is as good to be cautious towards outsiders. You don't know them. You don't know them, yet. And as you chance to encounter them, you will have a chance to come to know them, person by person. You will have this chance for every person you may ever meet.
You will only have it so long as you haven't poisoned yourself against them, by placing yourself in one false tribe - and them in another.