Ten years ago, American President Donald Trump descended an escalator and began his first campaign for President. Since that day, his rhetoric and policies have dramatically changed the American Overton Window – the range of what is politically acceptable. But Mr. Trump hasn’t merely shifted the Overton Window; he has dramatically degraded the quality of discourse and the standards by which Americans judge their political leaders.

That’s because Mr. Trump is corrosive.

In the ten years since he descended that escalator, Mr. Trump has corroded political and social norms, eroded institutions, and trampled on the rule of law. He has singlehandedly, systematically dismantled nearly a quarter millennium of American democratic cultural traditions. Our politics have gone from being merely divisive to being a zero-sum game in which even an iota of bipartisanship is seen as betrayal.

During Mr. Trump’s first term in office, the news cycle was driven by the outrageous things he proclaimed. The erraticism and chaos associated with Mr. Trump were notorious, but the damage he did was caused primarily by his words, rather than his policies. Mr. Trump was first impeached after he verbally blackmailed Ukrainian President Volodymyr Zelenskyy. He was impeached the second time when he verbally encouraged a mob to storm the U.S. Capitol Building and overturn his election loss. It was spur-of-the-moment verbal order by Mr. Trump that led to the infamous dispersion of protesters in Lafayette Square.

Despite Mr. Trump’s inflammatory rhetoric, his administration achieved policy victories well within the G.O.P. mainstream: the 2017 Tax Cuts and Jobs Act, the renegotiation of international mail, the Abraham Accords, the NAFTA renegotiation, and Operation Warp Speed all come to mind. On the international stage, Mr. Trump’s erratic and bombastic style even proved useful; White House aides were able to present themselves as beleaguered yet helpful allies working for a mercurial boss.

In the few places where Mr. Trump violated G.O.P. opinion, such as with family separation at the border, he backtracked. Although he was to the right of the Party, the Party constrained him. One of the great shifts in Mr. Trump’s second term is that the Republican Party can no longer fulfill that task.

Starting in 2015, Mr. Trump systematically corroded the Republican Party. For years, Mr. Trump called out the Republican politicians who were most strident in their opposition to him, catalyzing their own constituents to primary them out of elected office.

Mr. Trump exerted his corrosive influence over the G.O.P. even while he was out of office. Mr. Trump’s Big Lie about the 2020 election results, his claim that the January 6 rioters working to overturn the results of the election were patriots, his increasingly violent rhetoric, all became litmus tests for his fellow party members. One could loudly support Mr. Trump, choose not to say anything, or speak out. That latter group was small, and its members: Representatives Liz Cheney and Adam Kinzinger, among others, are now by and large out of office.

With a few exceptions, Mr. Trump is no longer calling out Republican politicians for being insufficiently loyal. That’s not because he’s changed, but because the Party has. There is no longer space in the Republican Party to publicly oppose Mr. Trump’s policies.

But Mr. Trump hasn’t only corroded our politics; he hasn’t only corroded the Republican Party, he has corroded himself.

Mr. Trump has surrounded himself with yes-men who don’t merely comply to his demands unthinkingly; his administration escalates and intensifies his whims into substantive policy. As Mr. Trump and his administration shift the Overton Window, Mr. Trump remains eternally on the Window’s rightmost flank. There is no end to Mr. Trump’s revanchist vision for the United States; merely an intensification of the reactionary policies he has already espoused.

Shortly after he was elected, political commentators rushed to discuss what Mr. Trump might do. For many, a consensus emerged: he would say a lot of uncouth things, but, like his first term, he would ultimately prove incapable of doing much permanent damage.

Boy were they wrong.

In the weeks since he took office, Mr. Trump has dramatically weakened his country’s position on the world stage. The collapse of U.S.A.I.D., the elimination of research grants, the end of R.F.E./R.L., and since rescinded plans to reduce military spending are all indicative of a United States which is turning inwards.

While Mr. Trump’s work signals that the United States is a less reliable international partner, his transformation of the United States’ internal politics is perhaps even more dramatic. Through threats, legal actions, and the incarceration and deportation of those who criticize him, he has caused self-censorship to spread across the nation. Many major media outlets are hurriedly instituting new norms intended to make the criticism of Mr. Trump’s administration more difficult. When Mr. Trump brings frivolous libel lawsuits against legacy media outlets, they now often choose simply to settle. Those who would once have been perfectly happy to be quoted criticizing Mr. Trump ask to be left anonymous, fearing retribution. Lawyers and law firms are intimidated by federal policy. Immigrants whose political speech is seen as inconvenient face deportation, sometimes to prison camps in Guantanamo Bay or El Salvador.

It is not surprising that the United States Congress, dysfunctional for years, has been unable to check Mr. Trump as he dismantles Congressionally-created agencies and tramples on the rule of law. But it is disturbing, if not surprising, that Mr. Trump has apparently defied a court order so early in his term. As I wrote before, Mr. Trump corrodes the standards of our discourse. Right now, it is seen as anomalous that Mr. Trump’s administration defied a court order; if the administration makes a regular habit of it, however, it will quickly become seen as the new normal.

Democracies don’t become autocracies overnight. They experience a shift of norms and of discourse. A corrosion, if you will. In the United States, it is becoming increasingly apparent that Mr. Trump is that corrosion.

The question is no longer: “Will President Trump try to criminalize speech he doesn’t like?” He’s already done that. The question is no longer “Will President Trump make the media give him more flattering coverage?” He’s already done that. The question is no longer “Will President Trump defy the courts?” He’s already done that. The question is: “Will anyone do anything about it?”