There is no shortage of hard-to-believe elements about the riot at the US Capitol on January 6 last year, but one of the things that may be hardest to believe is that many Americans claim to think former president Donald Trump bears no blame for what occurred.

For most observers, it seems safe to say, this is a surreal assertion. That there had never before been a mob of outraged individuals who swarmed into the Capitol on any January 6, the day on which electoral votes had been counted for decades, was not a coincidence. Never before had the losing candidate in a presidential election repeatedly claimed that he had won, much less a losing candidate with an Internet-powered megaphone and a political base centred so squarely on his personal piques and interests.

Trump spent months before the 2020 election sowing the seeds for his subsequent dishonesty. Since before the 2016 election, he had claimed that voter fraud is rampant in the United States, which it isn't. As the coronavirus pandemic upended election officials' plans, Trump transitioned his rhetoric from false claims about in-person voting to false claims about mail-in ballots. Going into November 3, 2020, experts fully expected the pattern that followed: Democrats, more wary of the virus, disproportionately cast votes by mail that in many places would be counted more slowly - meaning a predictable shift toward the Democratic candidate, Joe Biden. But for weeks before and then on the night of the election itself, Trump tried to derail this counting, insisting that only the votes already counted, ones that favoured him, were enough to constitute victory.

When his loss was confirmed on the morning of November 7, the real fight began. Trump had already been elevating any and all conspiracy theories about fraud that popped up in his various phone conversations and in his Twitter feed, but now he turned that effort more energetically toward getting political allies to intercede against Biden's win.

He had help. Recognising that Trump's obsessions quickly created small opportunities for profit, his allies constructed a system to amplify the idea that the election had been stolen. It is important to reiterate that all of these assertions about rampant fraud either still lack any credible evidence or have been explicitly debunked. After 15 months of review, there has been no concrete demonstration that the vote was systematically subverted in one single county, much less a state or a collection of states. But it remained profitable in attention and money for Trump and his allies to say it had been.

By mid-December 2020, Trump's attention turned to January 6. That may be because the Lincoln Project, an effort led by former Republicans that centred on needling the president, had identified the day as the one on which Vice President Mike Pence would be forced to certify Trump's loss. But Trump began explicitly encouraging people to come to Washington on that day and object to the election he said was stolen. (At a rally in Georgia two days before the riot, the WiFi password for press was "SeeYouJan6!") So they came by the thousands. The White House was involved in planning a series of events that day, most obviously the rally at the Ellipse - during which Trump encouraged attendees to march to the Capitol as he again made false claims about the election being stolen.

Again, it's weird to even have to restate all of this. Obviously the crowd that day was furious about an election they thought had been stolen, and obviously Trump had encouraged them to be there. It's useful to remember that scale was important; had 30 Proud Boys shown up to try to storm the Capitol, it wouldn't have worked. When hundreds of people decided to, it did. And those people were there and mad because of Trump. He opened the spigot fully on November 3, 2020, and the Capitol was flooded two months later.

And yet. In a poll conducted by The Washington Post with the University of Maryland, nearly a quarter of Americans say Trump bears no responsibility for what happened at the Capitol a year ago. The majority of that group are Republicans, nearly half of whom claim to think Trump bears no blame. No blame. Not just "Trump was not the only factor," but "Trump was not a factor“.

How? How can Americans believe that Trump is not culpable for what occurred, given how obvious that culpability is?

I would argue there are three reasons.

Misinformation As should be obvious, false claims about both the election and the riot have been central to the effort to distance Trump from that violence. That takes many forms, from sloppy efforts to rationalise his claims about fraud to dishonest presentations about what occurred that day.

Central to that latter effort has been Fox News's Tucker Carlson. He has repeatedly elevated unproven or disproved claims about the instigation of the riot, including in a three-part series centred on alleging that government actors made it happen. Yahoo News's Jon Ward looked closely at the series, finding - unsurprisingly - that Carlson does not make his purported case. This is not a new development for one of Carlson's claims.

One form of misinformation that has been rampant since January 6 is misinformation by omission, a simple failure by right-wing outlets to cover what happened in any great detail. Fox News, for example, covered sparingly the impeachment that followed the riot. In that recent Post-UMD poll, about a sixth of Republicans said that they didn't think any police had been injured by those engaged in the riot, a deviation from reality that can perhaps be explained in part by the lack of attention paid to that detail in conservative media. Many on the right have isolated images, like shots of rioters walking through the Capitol that day, as evidence that the riot was mostly peaceful - a belief held by more than a third of Republicans.

Rationalisation It has also been the case since shortly after the riot that some Trump supporters have sought to rationalise what occurred by comparing it to violence and vandalism that emerged after some protests during the summer of 2020.

This is not a great comparison for several reasons, including that the scale of that violence was often wildly overstated in the conservative media (again, see Fox) and that the Capitol riot was predicated on a demonstrably false claim about the election. Regardless, it's a weird defence of the rioters to insist that they somehow saw such actions as justifiable, given what they believed had occurred the previous summer, as though robbing banks is justified by a series of burglaries.

It has long been a feature of Trump support that his claims and behaviour need to be slotted into some category of acceptability. By January 2021, this process had been streamlined through repeated use. So it's not that the actions were necessarily rationalised in this way by those engaged in the riot as it unfolded (though some did) as much as that this rationalisation was applied after the fact to diversify culpability.

This is understandable. Millions of Americans invested in the idea of Trump as the salvation of American democracy. That’s hard to reconcile with his obvious effort to undermine the election results and his response to the riot itself as it unfolded, which could at its most generous be described as apathy.

Delusion Less understandable is simple delusion. This overlaps with misinformation, certainly, but involves simple rejection of the obvious facts at hand. Such as that the riot was caused by Antifa, a claim that emerged hours after the riot, was debunked and then re-rationalised. Deluded assessments of what occurred on that day are myriad and, in all cases, driven not by observed fact but desired outcome.

None of us is perfectly clear-eyed about anything. But on some things, objective reality is not particularly obscured.

January 6 happened because Donald Trump put into place the disinformation that it required and the call to action that energised it. Others bear blame, too, including law enforcement that was unprepared to prevent the attack despite myriad warnings, and Trump’s allies, who took his claims and turned them into a marketplace of dishonesty. But it all follows from Trump.

If Trump had held a news conference on November 7, 2020, and announced that he recognised Biden's win, there is no riot at the Capitol on January 6. It is fundamentally Donald Trump's fault, and there is no rational way to dispute that point.