The 17 thinkers who have contributed to this new collection of essays come down firmly on all sides of its central question: is the United States destined to become an authoritarian state? Multiple points of view are expressed by the book’s editor, Cass Sunstein, alone.

In his introduction, Sunstein writes: “My own summary of this book: Absolutely. It has happened before. It will happen again. To many Americans something like it is happening now.”

And yet 56 pages later, speaking only for himself, he says the opposite: “In my view, it really can’t.”

In another collection, such a contradiction might be a problem. Here, it isn’t. The medley of viewpoints expressed suggests something much closer to intellectual honesty than scholarly sloppiness. The truth is, no one can be certain. But whether you are an optimist, a pessimist or an idealist without illusions (John F Kennedy’s self-reverential description), this book bombards you with all the reasons that anyone who treasures democracy needs to be terrified by the current state of our republic.

It is, of course, the presence of Donald Trump in the White House that gives so many a sense of emergency. But like many other recent books, this one argues that the Trump catastrophe is really just the culmination of 50 years of constitutional decay, rather than some sudden, unpredictable event.

The Yale law professor Jack Balkin calls Trump a demagogue out of central casting, “unruly, uncouth, mendacious, dishonest and cunning”, his presidency a “symptom of constitutional rot and … dysfunction”. Balkin argues that the rise of American oligarchy is central to the steady decline of democracy.

He attributes the growth of oligarchy to changes in how political campaigns are financed (allowing gigantic amounts of dark money), basic changes in the structure of mass media which have “encouraged political distrust”, and the merger of “politics with entertainment”.

“The central goal of the Republican agenda,” Balkin writes, “… is to deliver benefits to the donor class”. Republicans have “no scruples about acting in an entirely shameless manner, as long as the interests of its masters are well served”. Trump’s populism is just a shameless “Potemkin village”.

Whether or not fascism is coming to America, it is undeniable that the internet has put more in place to make it possible than there has ever been before. Its infrastructure has enabled an almost complete (and barely protested) disappearance of privacy, and the near-disappearance of the very concept of truth.

In a particularly well-focused essay about how Russia is contributing to the rise of fascism, the former ambassador to the United Nations Samantha Power – Sunstein’s wife – says the current “media environment” gives “propaganda and falsehoods” unprecedented power.

Power provides extremely useful history on Russian efforts to interfere with US elections, which go back at least to 1984, when the KGB secretly campaigned against Ronald Reagan’s re-election. Just as they did during the 2016 election, the Russians spread all kinds of false stories, including the idea the CIA was plotting to give nuclear weapons to apartheid South Africa.

Then Power pinpoints why the Russians were so much less effective back then: “During the Cold War the vast majority of Americans received their news … via mediated platforms.” This meant that what they read or saw on television “had to get by professional gatekeepers”.

As far as the dissemination of news is concerned, that is the crucial difference between the pre- and post-internet worlds: the gatekeepers have disappeared.

Add to that the fact that bots accounted for 3.8m tweets in the final weeks of the 2016 election and that 38m false stories were shared on Facebook in the last three months of the campaign, and you get some idea of the damage the internet has inflicted on American democracy.

Fox News routinely “amplified falsehoods” that discredited Hillary Clinton. All in all it’s no surprise, as Power points out, that “large numbers of Americans now view as opinion what were once seen as verifiable facts” – everything from global warming to the utility of vaccinating children.

Several contributors focus on the potentially catastrophic reaction Trump could orchestrate in the wake of a large-scale terrorist attack. The Yale law professor Bruce Ackerman argues that the prospect of a “draconian response” by Trump “should jolt serious Democrats and Republicans” into passing a new statutory framework that would explicitly reject the claim made by Jay Bybee and John Yoo for the Bush administration “that the commander in chief has the unilateral power to make never-ending war on the home front”. Unfortunately, with spineless Republicans controlling both houses of Congress, there is zero chance of such an initiative now.

In the category of “it has happened here” already, the Harvard law school dean Martha Minow recalls the internment of 120,000 Japanese, including 70,000 American citizens, during the second world war. Despite intense “contemporaneous dissents” and “scholarly criticism”, the supreme court has never overturned the decision that made that horrendous episode possible. A Trump spokesperson even cited it as a worthy precedent for his proposed registry of immigrants from Muslim countries.

The University of Chicago law professor David Strauss highlights another instance when “it did happen in the US”. For roughly 80 years beginning at the end of the 19th century, “parts of the United States were ruled by an undemocratic, illiberal, racist regime” and “African Americans were denied the right to vote and were violently repressed … with the tacit approval of the government”.

Right now there are really only two things that can restore our faith in the rule of law and beat back lethal tendencies toward fascism. The first is a successful conclusion of special counsel Robert Mueller’s investigation into the alleged misdeeds of Trump and his dubious minions. The other is a new wave of energy from the progressive majority in the November elections, which could replace Trump’s Republican supplicants with Democrats who would actually impose serious limits on this White House.

As the New York University law professor Stephen Holmes puts it towards the end of the book, even if our system doesn’t “guarantee good governance”, a change in the team in power can still produce “a sense of buoyant expectancy” and “social energy throughout the community”.

The main reason for optimism about such new energy did not exist when this book was printed: the teenaged Americans now fighting to bring sanity to the nation’s gun laws. These magnificent young people must become the vanguard of a mass movement to rescue America from the Republican donor class – and to return it, finally, to its senses.

• Charles Kaiser is the author of 1968 in America – republished this month in a 30th-anniversary edition – The Gay Metropolis and The Cost of Courage.