Your book spans five decades of racist ideas. Please start with your own definition: What is a racist idea?

It is clearly one of the most controversial ideas. I wanted to simplify and clarify it as much as possible. I have defined a racist idea as any idea that suggests that a racial group is superior or inferior to any other racial group in any way.

You use five "tour guides" to lead us through different eras of thought - how hard was it to choose these individuals, i.e.: Cotton Mather, Thomas Jefferson, William Lloyd Garrison, Du Bois, and Angela Davies?

I had to find people whose lives were interesting and who I could tell this larger story through. Throughout the book there are fascinating ideas about these people. Like Cotton Mather, the first major character, basically urging black people to be Christianised because he believed that once people became Christians their soul became white. Or Thomas Jefferson who was simultaneously against slavery and against abolitionists, so I ended up describing him as this anti-slavery-anti-abolitionist. Or William Lloyd Garrison who somehow believed that slavery literally made black people into sub-humans, brutes who needed to be civilised. So I tried to describe these quite fascinating and oftentimes racist ideas.

Were you surprised at your findings?

I was surprised about the depth of their commitment to sustain discriminatory policies and how they used racist ideas to do that. Most surprising about these powerful figures is that they weren’t creating racist ideas because they were somehow ignorant and hateful, but that they were producing these ideas to defend discriminatory policies which were somehow benefiting them.

Did the project prompt you to reconsider your own attitudes?

Well I think that the racist ideas are extremely pervasive and widespread in American society - and they are consumed by people no matter their skin colour, including black people. Black people are consumed by racist ideas about black people: That’s how seductive and widespread these ideas are. In writing and researching this book, before I could identify and chronicle anyone else’s racist ideas about black people, I first had to confront my own.

Could you give an example of this?

I think one of the more pervasive ideas which exists in America and which I believed, was that black neighbourhoods are more dangerous. I think that is a global idea: We’ve been lead to believe that there is more crime in those neighbourhoods.

When I looked at the data on the U.S. communities which are considered high in crime, they are considered such because they have higher arrest and incarceration rates. We draw a straight line from crime rates or the amount of crime occurring in a neighbourhood to the amount of arrests and people being incarcerated. But we all know that people commit crimes and they are not arrested.

For us to assume that because a lot of people are arrested in a particular neighbourhood, they have more crime than another neighbourhood simply does not make any sense. That is especially the case in an environment in which people assume that black people are more criminal like, meaning they are more likely to be suspected and more likely to be arrested. Because people identify higher levels of violent crime in these neighbourhoods, they assume that the level of crime comes from the blackness of the people. But we know that there is no relationship between blackness and violent crime: That’s why in the United States you have middle income black neighbourhoods with far lower levels of violent crime than poor black neighbourhoods.

We also know that there actually is a relationship between unemployment rates and poverty and violent crime, no matter the racial group. So instead of us considering a neighbourhood a dangerous black neighbourhood, we should consider it a dangerous unemployed neighbourhood.

Very few people admit to being racist. What strategies help racists camouflage their prejudices and why have these strategies been so successful for so long?

Every racist idea has been like a post-racial idea, meaning that throughout American modern history, what racist ideas have done is say that social problems in our society are not discriminatory policies –but rather that the problem is people.

That is precisely what is happening now. People have been lead to believe that the very real problems they are facing are due to black people, or other groups.

At the start of your book you explain that a young black man was 21 times more likely to be killed by police than a young white man between 2010 and 2012. How does your history illuminate the current fraught chapter of race relations in the United States?

The Trump administration has not stated that racial discrimination exists. From his standpoint – and that of people who think like him - we are living in a post racial time. That means that the racial inequity in our country today is the result of black inferiority.

Then you have other forces like Black Lives Matter activists who refuse notions of a post racial society and thereby notions of black inferiority to explain racial inequality. They say that the inequities and the continuous shooting of black lives, with black people disproportionately killed by police, are as the result of racial discrimination. Assimilationists are saying that it's both, arguing that there is the problem of black people who are too criminal like, and the problem of racial discrimination.

You say racist ideas are secondary to racist political policy. Does the current U.S. administration use racist ideas to defend its political positions?

Sure and that has been so ever since black people have had the right to vote in this country. When black men were getting the right to vote in the reconstruction era their right to vote was crushed, not only by the Ku Klux Klan in the 1870s and 1880s, but also by the idea that black voters and the politicians they elected were corrupt and fraudulent.

In our political environment, that idea of the corrupt black voter has resurfaced to yet again oppress black voters. Republican politicians have passed a series of voter ID laws which they say are to eliminate voter fraud. When we show them that cases of voter fraud are nearly non-existent, they continue to ascertain that there are cases of voter fraud. If anything, they say, voter fraud is worse than we thought. Three to five million people voted illegally in the 2016 election, Trump has stated.

What I’m saying is that ultimately they passed these voter ID laws because they are recognising that the demographics of the country are shifting away from them.

Your book shakes up the reputation of key historical figures, attributing racist approaches to some of those credited with American abolitionism and civil rights activists. How was that received by readers?

You have people who read history to get a more sophisticated understanding of the world because they are reading with an open mind. Then you have people who read history to substantiate what they already believe or to further worship some hero that they feel is without fault.

Certainly those people who read history with a closed mind and who are keen to continue worshiping people that they love, they certainly had problems with the book. But then open-minded people who wanted a better understanding of the past and even more importantly, the world we are living in, they gained a better understanding of how we would become a nation that would elect Donald Trump.

And how can we cultivate anti-racist thinking?

To recognise that the racial groups are equal. There is nothing wrong with any racial group of people.