Brendan McDermid / Reuters

Trump aides colluded with foreign governments.

This is a simple, straightforward statement, and by this point, it ought to be an uncontroversial one. There’s ample evidence on many fronts, from legal documents to reliable reporting. This doesn’t mean that a crime was committed, because, as Trump lawyer Rudy Giuliani and others have pointed out, collusion is not a crime per se. But it does mean that attempts to dismiss the Russia investigation as a witch hunt that lacks any evidence are not merely disingenuous—they’re simply wrong.

What do we mean by collusion? As the Columbia Journalism Review explored last year, there are a range of meanings, but a clean synthesis would be a secret compact or conspiracy with an illegal or deceitful aim. The examples of such cooperation, between Trump aides and agents of foreign governments, abound. So far, three people have pleaded guilty to lying to federal agents about it. The unresolved question, at this stage of the investigation, is not whether such cooperation was attempted; it’s how successful it proved, how large an impact it actually had, who was involved, and whether they broke any laws.

There is, most prominently, the June 2016 meeting at Trump Tower, where Donald Trump Jr., Jared Kushner, and Paul Manafort met with a Russian lawyer they believed had damaging information to offer about Hillary Clinton. In another meeting in August 2016, also at Trump Tower, former Blackwater chief Erik Prince (the brother of Secretary of Education Betsy DeVos) brought together an Israeli social-media specialist and an emissary who said the crown princes of Saudi Arabia and Abu Dhabi wanted to aid the Trump campaign. The Trump campaign aide George Papadopoulos carried on conversations with at least two people he believed had substantial connections to the Russian government. Roger Stone, an on-again, off-again Trump adviser, exchanged messages with the hacker Guccifer 2.0, a Russian intelligence agent who released emails hacked from the Democratic National Committee.

This leaves out plenty of other examples of peculiar but less fleshed-out stories, including Trump campaign aide Carter Page’s mysterious trips to Russia and Hungary; fired National-Security Adviser Michael Flynn’s post-election discussions with Russia; and Jared Kushner’s reported attempt to establish a “back channel” to allow the Trump transition team to communicate with Russia outside of standard channels. There may be other examples that are not yet known to the public.

Because of the multifarious nature of the Mueller investigation, it’s possible to forget just how stark many of these cases were. In June 2016, for example, publicist Rob Goldstone wrote to Donald Trump Jr.:

The Crown prosecutor of Russia met with his father Aras this morning and in their meeting offered to provide the Trump campaign with some official documents and information that would incriminate Hillary and her dealings with Russia and would be very useful to your father. This is obviously very high level and sensitive information but is part of Russia and its government’s support for Mr. Trump—helped along by Aras and Emin.

Trump Jr. infamously replied, “If it’s what you say I love it especially later in the summer.”

Yet despite the evidence, and despite people like Steve Bannon acknowledging it, the question of whether or not collusion occurred persists well past its expiration date, lingering like a flat-earth theory. That there is still a debate is a testament to the president’s persistence in saying that no collusion occurred loudly and repeatedly, and in his strongest supporters’ willingness to believe him and take up the banner. The result might be termed Schrodinger’s collusion—at once very real and proven, and at the same time denied and held up as somehow an open question.

For months, President Trump has been reiterating that there’s no collusion. Here he is Wednesday morning:

and Tuesday morning:

and Sunday:

...and so on.

But Giuliani, who joined Trump’s legal team about a month ago, is taking a different line of argument: instead of denying that the Trump campaign colluded, saying it simply doesn’t matter because that didn’t break the law. Last week, for example, Giuliani spoke to Laura Ingraham about the June 2016 meeting at Trump Tower.

“When I ran against [Hillary Clinton], they were looking for dirt on me every day,” Giuliani said. “I mean, that’s what you do. It’s—maybe you shouldn’t, but you do it. Nothing illegal about that. And even if it comes from a Russian, or a German, or an American, it doesn’t matter.”

He also argued that because, according to those in the meeting, there was no actual exchange of “dirt”—instead, lawyer Natalia Veselnitskaya pressed them on the Magnitsky Act, a law detested by the Kremlin—the conversation was licit.

“And they never used it, is the main thing,” Giuliani said. “They never used it. They rejected it. If there was collusion with the Russians, they would have used it.”

Kellyanne Conway, another top White House aide, has also recently made the case that because collusion isn’t a crime, charges of collusion are irrelevant.

This is all actually a replay of last summer’s arguments. The emails that Trump Jr. released about the June 2016 meeting made clear that the Trump campaign was perfectly willing to collude, and was in fact frustrated that Veselnitskaya couldn’t deliver the goods Goldstone had implied. The president and his defenders contended that even if they had colluded, collusion was normal and even appropriate.

“He had a meeting, nothing happened with the meeting,” Trump said, referring to his eldest son. “Honestly, in a world of politics, most people are going to take that meeting. If somebody called and said, hey—and you’re a Democrat—and by the way, they have taken them—hey, I have some information on Donald Trump. You’re running against Donald Trump. Can I see you? I mean, how many people are not going to take the meeting?”

As I wrote at the time, there were a couple of flaws with the claim. First, it wasn’t clear that everyone would react that way. Former campaign staffers of both parties expressed shock that the Trump team had gone forward with the meeting, bringing up concrete examples where campaigns had gone to law enforcement in less egregious circumstances. Furthermore, although there is no crime of “collusion” per se, it is quite possible that a campaign-finance law could have been violated. Despite what Giuliani says about the source of the information not mattering, foreign nationals are prohibited from contributing to campaigns, and opposition research could represent an in-kind contribution.

The strategy of acknowledging collusion but insisting that’s OK because it is not illegal has another flaw. As with much of the discussion over Russian interference, it conflates the legal and political realms. Something can be legal while still being politically toxic; something can be illegal, but voters can shrug.

Giuliani in particular has tended to elide the distinction between the legal and political. Last month, trying to prove that Trump had not committed any campaign-finance violations, a legal argument, his account of Trump’s reimbursement to fixer Michael Cohen for a payoff to porn actress and director Stormy Daniels created a political mess. Giuliani has also adopted a strategy of attacking special counsel Robert Mueller’s probe as illegitimate and politically motivated, while largely ceding the legal arguments.

Many of Trump’s opponents have similarly conflated the legal and political. Elected Democrats have approached the Russia matter with trepidation, stifling talk about impeachment—a fundamentally political rather than legal procedure—and apparently hoping that Mueller’s probe will do enough damage to the president from the legal end that Democrats can reap the political benefits.

This week, Trump is in a tizzy over the revelation that there was an informant passing information to the FBI about the ties between some Trump campaign staffers and Russia.

Trump contends that there was no collusion, and that his campaign was being spied upon by President Barack Obama’s Justice Department for political reasons. The accusation of political spying has no evidence to back it up, and Trump has repeatedly made similar accusations of political interference, only to see them dissolve under the slightest scrutiny. The conspiracy theory also makes little sense: If Obama was spying on Trump to disrupt his campaign, why would he have waited until after Trump won to start leaking damaging information? If there was no collusion, and not even any evidence of collusion, it would be strange and disturbing for the FBI to be interested in what was going on inside the Trump campaign.

Yet we know that isn’t the case, because there was collusion. There was the June 2016 Trump Tower meeting, the August 2016 Trump Tower meeting, Papadopoulos’s contacts (which triggered the FBI’s investigation) and more. Manafort was serving as campaign chairman while angling to repay a Kremlin-tied oligarch for outstanding debts, to say nothing of allegations that Manafort was committing a raft of financial crimes including money-laundering. This doesn’t rule out the possibility of overreach and abuses by the intelligence community, but it gives a plausible reason why the FBI was interested in the Trump campaign.

There are many questions about Russian interference in the 2016 election that remain unanswered. Whether there was collusion between Trump aides and foreign governments is not one of them.