US President Donald Trump. Photo / AP
Much about the future of American politics - and about the historical judgment that will be visited on those associated with it - depends on the answer to one question: Is Donald Trump an instinctual demagogue or an instinctual authoritarian?
On most days, the evidence favours the former interpretation. Trump often acts like a desperate, self-interested politician, convinced that his enemies fight dirty and determined to out-slime them.
So he pursues a strategy of character assassination against the special counsel on the model of former president Bill Clinton discrediting Ken Starr.
This is squalid and damaging, but at least familiar.
Then there are other days - and more and more of them - that justify the latter interpretation.
Rather than a politician trying to muddy the waters, Trump seems more like a strongman probing the limits of democracy.
He seems less like Bill Clinton and more like Turkey's Recep Tayyip Erdogan, seeking to dismantle institutional checks on his authority.
"This is what it looks like," according to Republican Senator Jeff Flake, "when you stress-test all of the institutions that undergird our constitutional democracy at the same time."
The current flashpoint is the FBI probe of Russian influence on the Trump campaign - an investigation which made use of an informant in pursuit of information from suspicious Trump associates.
Trump has transformed this into a "spy" who was "implanted, for political purposes, into my campaign," constituting one of the "biggest political scandals in history."
This is accurate, except there was no spy, who was not implanted in the Trump campaign, in the course of an entirely legitimate investigation.
And Trump's charge of political motivation is absurd on its face, since the FBI investigation of Trump advisers was not made public before the 2016 election.
But the president's evident goal has nothing to do with logic, and everything to do with power.
Since the early days of his administration, Trump has believed that federal law enforcement should be under his personal control.
He has sought loyalty oaths and tried to make FBI investigations stop and start.
Now he has seized on a conspiracy theory to undermine public confidence in the FBI.
And the future of that institution now hangs by the thread of a few officials committed to the rule of law and the independence of law enforcement.
What would Trump prefer the FBI to be?
Consider the House Intelligence Committee under Congressman Devin Nunes, which has become a laughably partisan alibi factory for the president.
Or the Republican Party, which has become a pathetic propaganda tool for a leader who reviles his own party.
For Trump, this is what loyalty looks like: subservience.
Putting federal law enforcement under his personal, political control would be a danger to the constitutional order.
There is an authoritarian playbook, used (with some variations) in places such as Hungary, Turkey, Venezuela and Russia:
• Dismantle checks on executive power;
• Control the criminal justice system;
• Scapegoat minority groups;
• Co-opt mainstream parties;
• Discredit the independent press;
• Call for opponents to be jailed;
• Question the legitimacy of elections;
• Claim to be the embodied soul of the people.
Trump has praised and congratulated leaders who have done all these things - including Erdogan, Russia's Vladimir Putin and Egypt's Abdel Fattah el-Sisi.
And he has attempted some parts of the authoritarian playbook himself, particularly in his systematic attacks on law enforcement and the press and his self-conception as the voice for "real Americans."
"The only important thing," he said in 2016, "is the unification of the people - because the other people don't mean anything."
In a country with weaker institutions, argues former Secretary of State Madeleine Albright in her new book Fascism, Trump "would audition for dictator, because that is where his instincts lead".
Because Trump lives here, his authoritarian instincts are unlikely to dominate a government thick with balancing institutions.
But the stakes of our politics have dramatically changed.
If Trump were a typical politician, other Republicans could keep their heads down and wait for the storm to pass.
If his ambitions are autocratic, the cowardice of elected Republicans is indefensible and near to unforgivable.
Trump's enablers in politics and the media are reducing the political cost of undemocratic rhetoric and behaviour.
They are hurting the country in sad and lasting ways.
And it has become urgent to wake their sleeping courage.