If you’ve found yourself debating liberal friends on Facebook about Hillary Clinton’s email scandal recently, you’ve probably noticed that they are clueless.

They don’t know what Clinton did, and how she lied about what she did. They don’t know the basic law under which she was investigated, which is part of the Espionage Act. More interestingly, when shown the facts, most seem unable to admit she did something wrong, and that they are voting for her anyway, for other reasons. They are in denial.

There are a few reasons for their willful ignorance — some of which are specific to the political left, and some of which have to do with the nature of social media itself.

First, let us stipulate that there is some amount of ignorance on both sides, even — and sometimes especially — among otherwise well-informed people. We tend to filter out information that reflects badly on a candidate we have already chosen to support, and to focus on information that reflects badly on a candidate whom we oppose.

But the political left filters out more information than the political right. That is because the left, more than the right, tends to punish people who have the “wrong” views by marginalizing them.

In recent years, for example, college campuses — which lean heavily to the left — have increasingly “disinvited” controversial speakers, who are almost always conservative. If you worry that your friends might abandon you, you are less likely to consider facts that could lead you to contrarian conclusions.

Also, people on the left are less likely to be exposed to right-wing views than people on the right are likely to be exposed to left-wing views. That is because there are more liberal news outlets than conservative ones — even if individual conservative sources (like Breitbart) often are more successful.

On Facebook, the problem is particularly acute, because there is evidence that Facebook has deliberately suppressed news from conservative sources. The left-wing media bubble is simply thicker.

Yet part of the problem is simply the nature of social media, which is increasingly where Americans obtain their news.

Social media should theoretically make it easier for us to communicate with, and understand, one another. In practice, social media makes it easier to talk to people who already agree with us, and ignore or attack those who disagree. (The divisions among Republicans over Trump, for example, are probably far worse than they would have been in the absence of social media.)

There is, paradoxically, a narcissistic quality to social media. When people share baby pictures on Facebook, for example (as I do almost daily), they are not only communicating with distant relatives, but also admiring the pictures themselves. The same applies, especially, to “selfies.” People are more self-aware when they share personal information on social media.

And the same is true when they share news or opinion articles: they tend to share what makes them feel good about themselves.

Companies that produce social media content understand that, and so they shape articles (like this one, for example) so that the headlines and descriptions flatter the pre-existing views of their readers — which they, in turn, also shape and reinforce. Liberal websites like Buzzfeed and Huffington Post — which have explicit anti-Trump editorial policies — do it, and so do conservative sites like Breitbart.

What is different about the Clinton email scandal is there is literally nothing good about it. There are only two options: either Clinton committed a crime, or she was careless with national security. And either way, she lied shamelessly.

None of those alternatives makes Clinton supporters feel good. In theory, it should be possible for them to say: “You’re right — she lied, she was extremely careless, but I still support her” for whatever reason.

A Clinton supporter might say that face-to-face. But it’s like a frowny baby picture — understandable, perhaps, but not flattering. Denial is the much easier option.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. His new book, See No Evil: 19 Hard Truths the Left Can’t Handle, will be published by Regnery on July 25 and is available for pre-order through Amazon. Follow him on Twitter at @joelpollak.