Thing I wrote. It started as a response on other thread, but got kind of long and preachy. Figured I'd dump it here:
Traditional liberals believe that a diversity of opinions is vitally important, because no man, ideology, religion, etc. has a monopoly on truth. Everyone is fallible. Ideas we agree with, or even strongly support, are done a disservice when not confronted by worthy criticism. No idea is beyond reproach, and even the best ideas can be improved by addressing challenges. This can be generalized beyond abstract ideas to habits, cultures, heuristics, norms, and so on. Traditional liberals celebrate tolerance and abhor bigotry, at least in part, because of a spirit of epistmic humility. However strongly you may feel about an idea, you should never cross that line into denying people a right to believe and speak freely. Ultimately, such repression and censorship cuts off the very feeback and criticism we need to make progress, and it creates an orthodoxy untethered to reality and open to abuse.
One of the ways that the modern progressivism has jettisoned this liberal ideal is by embracing an explanation of evil, i.e. racism, where great harm is done by people even privately disagreeing with it.
Legal rights were equalized long ago, various forms of affirmative action and institutionalized pivileges were introduced for previously oppressed groups, and meanwhile the attitudes and values of the general populace have changed dramatically. The media, academia, and political class all resoutely and uniformly condemn racism, and ordinary people can be fired from their jobs for just saying something that a white supremacist might say when trying to hide his opinions. Most examples of intolerable racism highlighted by the meda are wild exaggerations, mere supposition, anonymous trolls, or outrigt frabrications. Actual honest-to-God white supremacists are rare, scattered, and have little or no institutional influence or power. To the extent that any white nationalist is popularly known, like Richard Spencer, it is mostly because he is fun to hate-on rather than because he enjoys much earnest support.
However, despite everything, various racial discrepencies and gaps still persist. This wasn't supposed to be. Sure, things have gotten marginally better, but the relative standing of blacks, in particular, has changed little. Practically every major institution appears to have undergone radical change to eliminate he scourge of racism, and more people than ever are not only explicity anti-racist, but are eagerly taking part in social movements to stamp out any residual racism. This residual racial animus that still exists, then, must now bear a great explanatory burden, because it must, somehow be responsible for the persisting discrepencies and gaps that are regarded as intolerable racial injustices.
It turns out that racism is a more subtle and pernicious evil than anyone previously expected, because it still exerts a near undiminished influence even from its secret underground hideout under an old shed the middle of nowhere. The causes of racial injustice have narrowed to unconscious biases, instances of micro-racism, and invisible systemc forces that have become ever more ethereal and metaphysical. The process of determining what is to be racist each week is looking more and more like crowd-sourced tea leaf reading. So we've eliminated the racist polices and most of the racist speech (and then some), we've fired the racists and continue to purge any sympathizes, but it hasn't and still isn't working. Slowly, we've honed in on what must be the final cause of racial injustice--dissenting speech and ideas.
The private speech and opinions of doubters and dissenters are all that is left to explain the great evil of the suposed white supremacy. The open dissenters may be few, their words often censored, their preferred social policies verboten, but they still have opportunities in their day to day lives to act on their opinions. Perhaps they exhibit insufficient deference to the lived experience of a minority, or maybe they avoid passing through black communities because they stereotype them as having a crime problem. There are innumerable small ways in which dissenters from the progressivism can exercise their personal freedom to perpetuate racial injustice. It is a moral imperative to stop them, since their actions are doing measurable harm to minority groups.
The old liberal ideal is inoperable in this circumstance, because too much is at stake. We cannot tolerate dissenting speech and opinions when they are themselves the only remaining explanation for the evil we see around us (epistemic humility notwithstanding). This is no longer room to agree to disagree. If you dissent, then you are actively contributing to white supremacy. Once someone has internalized this lesson, it becomes very difficult to have a productive debate, because the act of dissenting is itself a kind of stochastic violence. Contrary opinions, even when they have negligible practical influence, are the root cause of a terrible social ill, and to give them voice is morally irresponsible.
In place of the old liberal safegaurds against creating an orthodxy untethered to reality and open to abuse, we must depend on the fact that progressives are just good, well-meaning, and compassionate people who just want to make the world a better place. In Twitter we trust.