Racism is one of the most difficult subjects you can write about. What lies at the heart of racism? Is there ever a single cause? Can it be understood rationally? And if so, is there an answer to it?
The first obvious impulse that could lie behind it is a sense of differentness. A minority race can look, or act, differently to the majority, and this can lead to non-understanding, and in non-understanding we find fear.

normality

A majority is what is seen as ‘normal’. Anything that does not seem to fit this ideal will cause an impulse towards marginalization. As well as showing what is ‘wrong’ with such a minority, this also confirms what is ‘right’ about the majority. In this way, concepts such as good and evil are born.
This leads to racism as an intellectual pursuit. First seen in various religious theologies, such intellectual racism was given a boost by evolution theory. This allowed a different race to be seen as being of a lesser evolutionary stage than a majority. The science and discipline of eugenics was born from such an ideal.

intelligence

A predominant culture can add to the problem. Intelligence is more than your ability to be wise. It is also an ability to relate to your culture in a way that can be seen as intelligent. People not of a predominant culture cannot relate in the same way, so can be incorrectly seen as intellectually inferior.
As such, if a society has a predominant idea about itself, it cannot be anything other than racist. However, this is a form of racism based not on hatred, but simply the way humanity works.

multi-culturalism

Some see the answer in diluting culture. Known as multi-culturalism, it subverts a predominant culture. This is a bad idea. It is contrary to free speech, and it takes away any hope of shared values. The result is a cauldron of multiple racial hatreds.
The answer, I’m sure, is to work towards an over-culture with shared values. This MUST include meaning identified by the predominant race, but taking into account differentness by including a spirit of compromise, toleration, moderation and manners.

pogroms

At times these natural differences can boil over. A classic case is poverty. At such times, natural differences become extreme, and it is here that a pernicious hatred arises which can lead to pogroms, even genocide.
It begins with an ideal based on bigotry. An extreme form of politics will arise, and at the heart of it will be a form of scapegoating. The society is actually crumbling because of faults in the majority culture, but those faults will be placed on a minority. After all, an angry society never blames itself.

psychology

A concept arises that can best be called ‘psychological distancing’. It takes intuited differences and makes them fundamental. Assisted by extreme intellectual racism, the scapegoated minority becomes sub-human. In being sub-human, this removes moral restraint, and atrocity becomes ‘acceptable’.
Transference has then occurred. By this, I mean all the angst and failures of a predominant culture become symbolized in a stereotypical minority form. A minority no longer consists of people, but is a concept which must be eradicated.
Of course, this is just a quick look at racism. In it, I’ve tried to show there are degrees. At the lowest level, it is a natural condition, and no amount of denial will change it. Accept it and we may learn how to live with it. Then, at the extreme, we have the stuff of nightmares. Yet I think the best way to understand this form of racism is as a form of social virus. Maybe if we thought of it as an illness, we can work on a cure.