"It’s surprising to think of racial bias as not just a state or habit of mind, nor even a widespread cultural norm, but as a process that’s also part of the ebbs and flows of the body’s physiology." This startling article from Aeon reveals how racial prejudice is connected to biological functions, and thus is more difficult to overcome than our Enlightenment-based rational hopes imagined.  

Please read the article.  Here is the conclusion:

On the one hand, this is a reason for optimism: if we can better understand the neurological mechanisms behind racial bias, then perhaps we’ll be in a better position to correct it. But there is a grim side to the analysis, too. The structures of oppression that shape who we are also shape our bodies, and perhaps our most fundamental perceptions. Maybe we do not ‘misread’ the phone as a gun; we might we actually see a gun, rather than a phone. Racism might not be something that societies can simply overcome with fresh narratives and progressive political messages. It might require a more radical form of physiological retraining, to bring our embodied realities into line with our stated beliefs.

This raises an important question in political liberalism.  Mill believed that society should not be overly involved in the effort to morally shape people, instead allowing them the liberty to develop on their own.  His initial radical left-wing idea now sounds closer to libertarianism.  It also sounds naiive, as we've learned that issues like racial justice cannot be solved by simple education of the reason.  

So I think about a variety of inputs--Michael Sandel's arguments in Justice that society must discuss the purpose of what it means to be human, Jonathan Haidt's research into the psychological impulses behind our political views, or Martha Nussbaum's book on how a democratic society must engage in moral education of its citizens by using the emotions.  These ideas run up against the ideas of Mill, which initially sound lovely, but flounder on the rock of reality.

See this earlier post on the liberal paradox.