Race is a socially constructed category. The idea that someone is a different "race" just because they look different is not supported by biology. In all metrics there is more variation within a group than between groups. So the "tenets of racism" have been decisively disproven many times over.
The problem with defeating these in the marketplace of ideas, so to speak, is that their propagation has nothing to do with logic. People who believe them would find a way to dismiss any logical counterargument. The only way to squash it, arguably, is to prevent it.
Not to mention the fact that people who are targeted by these ideas, which deny their humanity, are going to feel hurt and excluded in any space that allows it. So preventing that from happening is a real-time, concrete concern.
The problem with defeating these in the marketplace of ideas, so to speak, is that their propagation has nothing to do with logic. People who believe them would find a way to dismiss any logical counterargument. The only way to squash it, arguably, is to prevent it.
Not to mention the fact that people who are targeted by these ideas, which deny their humanity, are going to feel hurt and excluded in any space that allows it. So preventing that from happening is a real-time, concrete concern.