As Donald Trump extends his control over the Republican party, American conservatism has entered a pseudo-Orwellian stage where weakness is strength, appeasement is toughness, lies are truth, and “America first” means “blame America first”.

The fiasco in Helsinki, where the president openly sided with Vladimir Putin over his own country’s intelligence agencies, was not a one-off for this president but rather an exclamation point on what has happened to the American right.

For me, as an outspoken conservative for the last four decades, the experience has been vertiginous. On one issue after another – from Russia and free trade to corruption and the rule of law – Republicans have adjusted their principles to conform with Trumpism, which often means with Trump’s latest glandular impulse.

I came of age watching Ronald Reagan call on Mikhail Gorbachev to “tear down this wall”, as he reasserted America’s role as leader of the free world. Last week we saw Trump insult our allies, undermine our friends and truckle to the Russian autocrat.

Given a chance to hold Russia accountable for its attacks on the American election, its annexation of Crimea, its aggression in Ukraine, its role as an enabler of Syria’s Bashar al-Assad, or the murder of journalists and political opponents, Trump chose instead to blame “both sides”:

Yes I do. I hold both countries responsible. I think that the United States has been foolish. I think we’ve all been foolish … And I think we’re all to blame.

It is impossible to imagine Reagan or, frankly, any other US president, giving that answer, and it is easy to imagine the outrage among conservatives if Barack Obama had uttered those words. This was not an errant tweet, or one of Trump’s random insults, outrages or assaults on the truth. Trump’s behavior risked undermining the global world order, alienating our friends and emboldening our enemies.

Many Republicans have rationalized their support for Trump by pointing to tax cuts, rollbacks in regulation and Trump’s appointments of conservative judges. But last week reminded us how many of their values they have been willing to surrender. Moral relativism and its cousin, moral equivalency, are not bugs of the Trump presidency; they are central to its diplomatic philosophy. Unfortunately, polls suggest that many conservatives are OK with that, despite the betrayal of what were once deeply held beliefs.

For years, Republicans derided what they saw as Obama’s fecklessness on the world stage, including what they called his “apology tour”. Trump, we were told, would change all of that by projecting strength and standing up for American values. Instead, we got last week’s parade of sycophancy and abasement.

This ought to have been a clarifying moment. Trump was supposed to be the Man on the White Horse who promised that he alone could solve all of our problems. Instead, he looked like Putin’s caddy.

The problem is that many conservatives have confused the swagger of the schoolyard bully with actual strength

The problem is that many conservatives have confused the swagger of the schoolyard bully with actual strength; we saw how Trump behaves when he’s confronted by an even bigger bully. He groveled, and then hedged, then tried to walk it all back with the absurdly laughable claim that he confused the word “would” for “wouldn’t”. Depressingly, that was good enough for some Republicans, including the Ohio senator Rob Portman, who said he was willing to take Trump at his word.

But we’ve seen this movie before, as Republicans react to Trump’s outrages by wringing their hands, only to fall back into line.

Understandably, this feeds the impression that we should regard Trumpism as a logical and organic outgrowth of conservatism rather than an existential threat to that tradition. That is, of course, the view from the (Sean) Hannitized right, which insists that opposition to Trump among so-called Never Trumpers is a form of apostasy.

But a similar argument is advanced by a chorus on the left. “Donald Trump Was the Inevitable Result of Republicanism”, declared a recent headline in Esquire. With every passing week, as outrage piles on outrage, that argument admittedly becomes more difficult to refute.

But a few points need to be made about the attempt to equate Trumpism with traditional conservatism. The first is the most obvious: if Trump was the inevitable and predictable outcome of the conservative movement, why did none of those critics predict his coming?

They also need to explain why Trump is more an “authentic” expression of conservatism than previous GOP nominees, like George HW Bush, John McCain or Mitt Romney. Distinctions are important here: it is unhealthy and intellectually sloppy to gloss over the fundamental differences between the conservatism of a Milton Friedman and the raw nationalist nativism of a Steve Bannon, just as it is intellectually dishonest to confuse the progressivism of Adlai Stevenson with Che Guevera. Nuance matters.

In November 1985, Ronald Reagan, his wife Nancy and an aide, left, meet Mikhail Gorbachev, his wife Raisa and an aide in Geneva, Switzerland. Photograph: AP

Obviously, Trump has deftly exploited many of the grievances and attitudes that have festered for decades on the right. But that’s not the whole story. Trump has more in common with populist demagogues like the “Know Nothings”, Father Charles Coughlin, George Wallace and Pat Buchanan than with conservatives like George Will or Ronald Reagan. Until the last election, conservatives had the good taste, sound judgment and wisdom to reject and even marginalize those uglier voices on the right. In that sense, Trump is the exception, rather than the rule.

Perhaps the best way to think about Trump’s nativism and isolationism is to see them as recessive genes in conservatism that had been kept in check for generations. That also suggests another tradition exists, even if it is now in eclipse.

While it’s easy (and tempting) to define a political movement by its worst aspects, it bears noting that modern conservatism also gave rise to Charles Krauthammer, Ross Douthat, Peter Wehner, Ben Sasse and Jeff Flake. In other words, it didn’t have to be this way, and it doesn’t have to continue in the future.

The real danger, however, in seeing Trump as the logical, organic product of conservatism is that it normalizes him. Discounting the peculiarity of his rise ignores the uniqueness of the danger he poses and the urgent need to confront the damage he is doing to the body politic and our political culture. If he is merely another Republican, there no cause for more than the usual alarm.

But last week reminded us that there is nothing normal about Donald Trump or the existential threat he represents. It is long past time for conservatives and Republicans to recognize that.