You’re making the incorrect assumption that racists are arguing in good faith and are willing to change their minds after a well thought out intellectual, level-headed discussion. But history has shown us this almost never happens. The majority of them are basing their hatred on emotion and not rationality.
Instead, racists use their platforms to intimidate at-risk minority groups and intimidate them into silence. White supremacists are actively trying to silence those they disagree with, often with violence, not trying to have an intellectually honest and open discussion.
Read about Karl Popper and The Paradox of Tolerance.
There’s no such thing as anti-white racism. Racism is prejudice or discrimination backed by institutional, structural power.
Therefore, a black person prejudiced against white people (as an example) is meaningless because black Americans have historically had very little power in the United States.
Racism by white americans has historically been backed up by the power of every institution in the United States, which often has meant state-sponsored violence against people of color.
I think most people recognize that this is the "new definition" of racism, or sometimes people refer to it as structural racism. But when people use the term racism, they usually mean the standard dictionary definition, which is about being prejudice against someone because of their race.
It's probably better if people used "structural racism" to define what you mean here. Similar to how "sex" retained the original definition of sex, and "gender" was used for the social construct. If people tried to say "There is no such thing as being born with a binary sex, because sex is a social construct" then it would be equally confusing.
The "old" definition of racism was something like "having an opinion about someone based on their race" and was essentially indistinguishable from the concept of stereotyping, where someone "judges a book by its cover" and makes assumptions based on what someone looks like.
Today we understand that that kind of stereotyping is a universal attribute of human cognition and therefore not explanatory. That is, you can't get from that definition of "racism" to the society we see around us today. Every human does it--everyone is "racist" by that definition--yes, including black people. And yet black people are still far worse off, on average, than whites in American society.
So that definition of racism is useless. It doesn't explain why things are the way they are, and we can't change the way our brain works at such a fundamental level anyway. It has even become a joke--see Stephen Colbert's riffs on "I don't see color."
So yes, the concept of racism has evolved to include power. Without power, stereotypes don't have an opportunity to cause actual harm. You have to consider power to understand why American society, on average, treats white people and black people so differently.
What counts as "changing the meaning of a word" and what counts as higher, more complex, and more abstract understanding of (originally) lay concepts? For example, if the common conception is that "math" means something like arithmetic, and mathematicians point out that it has a much broader, abstract, complex, and encompassing definition within their field of study, are the mathematicians engaging in Orwellien redefinition of language?
The academic feeling among people who study these topics (socioloists, anthropologists, philosophers) is much closer to what GP defined as racism than the definition you (probably) had in mind.
How many of said academics do you honestly, seriously, truly think don't have leftist political tendencies? You seriously expect to get a completely unbiased opinion out of them? Come on. No matter your political leanings, surely you are willing to admit socialist beliefs prevail in non-STEM academia?
By this definition, if Adolf Hitler had gone to live in Israel, a majority Jewish democracy, he would no longer be a racist, because his “prejudice” was no longer “backed by institutional, structural power” - have I got that right?
No, it's not like that, GP has the wrong conception of the topic. Racism is the thought or ideology alone. This means that the hypothetical Hitler in Israel still fulfils the definition.
Conflating racism with the power to put the supremacist wishes and ideas into practice is somewhere between pointless and negligently dangerous.
As a foreigner, and frequent traveler to the US for some 20 years, find it hard to believe it is still present in any other way than marginally at the US's institutions. Can you point me to some examples?
One example is how the police are far more likely to shoot and kill unarmed people of color in the US[1].
Another example is how people of color in the US are far more likely to be incarcerated than white people are, especially for non-violent offenses.[2]
There's a reason the George Floyd protests have been so intense: His death was no isolated incident, but a pattern of continuing discrimination against people of color in America by those who control the power structures.
Some contemporary evidence would make this argument stronger. (I say contemporary because I guess we all understand what Hitler did.)
My feeling is that a "platform" on Twitter where you abuse and troll people is very different from a platform where you have to step up in public, make a speech, have people challenge your points and so on.
Instead, racists use their platforms to intimidate at-risk minority groups and intimidate them into silence. White supremacists are actively trying to silence those they disagree with, often with violence, not trying to have an intellectually honest and open discussion.
Read about Karl Popper and The Paradox of Tolerance.