In his State of the Union speech on Tuesday night, President Trump delivered what was superficially the most "presidential" speech since he recited the oath of office. He took credit for a booming economy and a genuinely laudable effort at criminal justice reform, made numerous call-outs to appealing guests in the chamber, denounced socialism, (dishonestly) claimed to favor higher rates of legal immigration, talked tough about Venezuela and Iran, promised to plow money into building infrastructure, praised women, and even came out in favor of paid family leave.

If the speech had been limited to these items, and if the president himself were capable of following through on his most popular proposals, his administration might not be as impotent as it is. Moreover, Trump himself might not be stuck 10-15 percentage points under water in his approval ratings. But he is — and the content of the speech, no less than the manipulation that took place in the hours leading up to it, explains why.

Like all presidents going all the way back to George Washington, Trump claimed to want unity, to speak for and to all Americans, regardless of party. That's what presidents always do. In the most famous and moving example, Abraham Lincoln talked in his second inaugural address about the collective sins of the entire nation, North and South alike, while the Civil War still raged.

But the trick no longer works like it used to. The country is too divided now. Not as violently divided as we were in the 1860s, but more than divided enough for partisans to speak different ideological languages, and sometimes to inhabit entirely distinct conceptual (and even factual) universes. The area of overlap is shrinking, which means that the number of common appeals that can actually manage to reach us is rapidly dwindling.

The last president who managed to be heard by all Americans was George W. Bush in the months immediately following the 9/11 terrorist attacks. But then the Iraq War buildup began, followed by the invasion and insurgency, and then Bush's re-election campaign, which took base mobilization in a general election contest to new heights. The result was sharp division, and as a country we've never looked back.

Barack Obama burst on the national political scene with a speech that spoke of a higher America beyond partisan division, and he never abandoned that classically presidential aspiration. But it was paired with remarks on the campaign trail about Republican voters that infuriated them. ("They get bitter, they cling to guns or religion or antipathy to people who aren't like them or anti-immigrant sentiment or anti-trade sentiment as a way to explain their frustrations.") And as president, Obama used the same lofty rhetoric to advance policies that his ideological opponents found just as antagonizing. That had the unintended effect of cheapening the words, and sowing a cynicism that Trump and the gutter faction of the GOP weaponized to great effect during the 2016 election.

As it did a year ago, Trump's communications team made it clear to the press in the days leading up to the State of the Union that he would make an effort to bring the nation together, to foster unity, with his remarks. Yet as he also did a year ago, Trump spoke to members of the press on the day of speech and made lacerating remarks that he must have known would end up being leaked. (They were.) That pleased the president's base and "triggered the libs" while also giving him an occasion to bash the press for its dishonesty.

That was the immediate backdrop for Trump's "unifying" speech — along with, of course, the record-breaking government shutdown over funding for the president's border wall, which is strongly supported only by a right-wing faction of his own party. The State of the Union included a strong pitch for that wall, as well as a promise that he would build it.

The speech also referred to "the Democrat Party," a childish shortening of the word "Democratic" that Republicans employ purely to annoy their ideological opponents. And suggested that "partisan investigations" of his own administration's corruption (including allegations of collusion between the 2016 Trump campaign and Russian intelligence) would jeopardize the country's peace and prosperity. He also attacked the Affordable Care Act, the signature domestic policy achievement of the Obama administration. And he bragged about scuttling the Iran nuclear deal, the singular foreign policy achievement of the Obama administration. And he laid into the North American Free Trade Agreement, one of the major achievements of the Clinton administration. And so on and so forth.

It was a sharply partisan speech interwoven with weak (and sometimes imaginary) rhetorical gestures toward bipartisanship and unity. In another era, it might have been possible for a president to pull that off. But in 2019, deep into an age of polarization, it is impossible. Not least because Trump himself has no idea how to follow through on such gestures. He is a man of combat and animus. Even when he claims to be bringing us together, he tries to conquer by dividing.