Liberals find President Trump's corruption, ignorance, atrocious judgment, and authoritarian instincts self-evidently appalling, just as they are instinctually disgusted by the undisguised cruelty of the administration's proposed federal budget and the health-care bill passed by the Republican majority in the House. That's my reaction, too.

But too many liberals also assume that this reaction will be automatically shared by everyone, if only the facts are presented to them.

This assumption is false. It's an outgrowth of the deeply rooted liberal belief in progress. Most liberals really do believe, sometimes deep down but often right on the surface, that they are bound to prevail, inevitably, in the fullness of time, and quite likely very soon, just around the corner, despite minor setbacks like the election of Donald Trump.

This isn't an empirical claim. It's a confession of faith — one that liberals desperately need to rein in and check if they hope to make gains in upcoming election cycles.

But that is unlikely to happen if liberals keep listening to the likes of political scientist Ruy Teixeira.

No personal offense to Teixeira intended. He's clearly very smart, and he seems like a nice guy. But he's also the co-author of The Emerging Democratic Majority, the 2002 book that did more than any other to convince liberals that the future would be theirs if only they waited for it to land in their laps. Demography is destiny, after all, and demographic groups that vote Democratic (mainly minorities) are growing while those that vote Republican (mostly whites) are shrinking. The result? A future that's bound to belong to liberals.

It would be one thing if the inevitable Democratic triumph appeared merely to be stalled — or if Teixeira responded to recent discouraging election results by changing his incorrigibly optimistic tune. But neither is the case. The "emerging Democratic majority" hasn't just been delayed; it's been reversed at every level of government (federal, state, local), with the party left (as one prominent pundit put it in the immediate aftermath of the 2016 election) a "smoking pile of rubble." (The premises of the original demographic thesis have also been called into question.)

As for rethinking, Teixeira shows no signs of backing down from his happy talk. Back in April, he took to Vox to spell out "7 reasons why today's left should be optimistic." (Reason #5: "The left's coalition is growing while the right's is declining.") And now he's back to tell us that, according to polls, liberalism is "surging." (Vox should consider embedding an audio player queued up with "Oh, What a Beautiful Morning" the next time Teixeira files a piece, to put readers in the proper mood.)

Do some polls show liberal gains since the election that delivered the White House to Trump? Yes, they do. And it's certainly possible that the full-court dysfunction, putrid odor of scandal, and outright brutality on flamboyant display in Republican Washington might be enough all on its own to deliver power to Democrats across the country in 2018 and 2020.

But nothing at all in recent political history gives liberals reason to think that they'll benefit by complacently waiting around for the other party to self-destruct. Because his optimism inspires such complacency, Teixeira is a dangerous man for Democrats to have around.

Consider the disaster of the Hillary Clinton campaign. The candidate and her team were thrilled to be facing Trump in the general election. What a gift! Clinton's opponent was so self-evidently awful that she might not even have to campaign that hard!

How do we know that this was their reaction? Because … Clinton didn't campaign that hard! From the end of July (just after the Democratic convention) until the eve of the first debate on Sept. 26, Clinton stayed largely out of the public eye. And in the crucial last six weeks of the campaign, she devoted an inordinate (utterly unprecedented) amount of time, energy, and resources to highlighting Trump's extremely well-known dreadful behavior (which was already receiving wall-to-wall coverage in the media).

What she didn't do was articulate a compelling contrary vision of her own that would respond more positively and productively than Trump himself to the discontent that propelled him to his party's nomination (and also fired the surprisingly formidable primary campaign of Bernie Sanders). She thought standing there, pointing, and looking appalled at the Republican candidate would be sufficient.

It wasn't then. It isn't now. And it won't be in the future.

What liberals need is not optimism, which can easily breed arrogance and cockiness as much as complacency. They need passion (fueled by anger at Republicans), a compelling alternative vision of the country's future, and a commitment to persuading voters to support it. And they need to press the fight, relentlessly, at all levels of government.

Hearing from Teixeira and other Panglossian pundits that the effort is bound to prevail can make for a nice pep talk, but it's also likely to make liberals less hungry, less focused on the need to fight for every square inch of ideological territory against a ruthless opponent.

If a Democratic majority really is going to emerge, liberals will need to work for it, hard. Telling them they're bound to enjoy the fruits of victory no matter what they do runs the considerable risk of sabotaging that very outcome. Which is a very good reason to avoid telling them any such thing.