It’s always important to understand how you know what you know, or what you think you know. It’s particularly important in the case of the Trump dossier.

Consider the increasing number of claims that the incendiary allegations of the dossier “check out,” in the words of New York Times columnist Bret Stephens.

Bankrolled by the Hillary Clinton campaign and the DNC, guided by the dirt-digging opposition research firm Fusion GPS, and compiled by the former British spy Christopher Steele, the dossier’s key allegation is this: “There was a well-developed conspiracy of cooperation between [the Trump campaign] and the Russian leadership.” Steele attributed that claim to “Source E,” whom he described as “an ethnic Russian close associate of Republican presidential candidate Donald Trump.”

“What’s relevant is [Steele’s] credibility, the reliability of his sources and the truthfulness of their claims,” Stephens wrote recently. “These check out.”

But do they? In reality, most reasonable people not named Mueller would have to say we don’t know.

“As it relates to the Steele dossier, unfortunately the committee has hit a wall,” Senate Intelligence Committee chairman Richard Burr noted last month. The committee’s investigation, the best probe outside of the Mueller special prosecutor operation, has not even been able to discover who Steele’s sources were, Burr said.

So how do outsiders conclude that the document’s key allegations check out? How do they know what they know?

Consider one of the dossier’s underlying claims in support of the “well-developed conspiracy of cooperation” between Trump and the Russians. In a section of the dossier dated July 19, 2016, Steele wrote Carter Page, who was briefly on Trump’s little-used foreign policy advisory team, held secret meetings with two high-ranking Russians, one in the Putin government and one the head of Rosneft, the state-owned oil company, during a visit to Moscow early in the month of July. Here are the relevant portions of the dossier, written in spy style, from the July 19 Steele memo:

Speaking in July 2016, a Russian source close to Rosneft President, PUTIN close associate and US-sanctioned individual, Igor SECHIN, confided the details of a recent secret meeting between him and visiting Foreign Affairs Advisor to Republican presidential candidate Donald TRUMP, Carter PAGE.
According to SECHIN’s associate, the Rosneft President (CEO) had raised with PAGE the issues of future bilateral energy cooperation and prospects for an associated move to lift Ukraine-related Western sanctions against Russia. PAGE had reacted positively to this demarche by SECHIN but had been generally non-committal in his response.
Speaking separately, also in July 2016, an official close to Presidential Administration Head, S. IVANOV, confided in a compatriot that a senior colleague in the Internal Department of the PA, DIVYEKIN (nfd) also had met secretly with PAGE on his recent visit. Their agenda had included DIVYEKIN raising a dossier of ‘kompromat’ the Kremlin possessed on TRUMP’s Democratic presidential rival, Hillary CLINTON, and its possible release to the Republican’s campaign team.

That was in July. Later, in a dossier memo dated October 18, 2016, Steele wrote that his sources had re-confirmed the Page-Sechin meeting, and offered sensational new details:

Speaking to a trusted compatriot in mid October 2016, a close associate of Rosneft President and PUTIN ally Igor SECHIN elaborated on the reported secret meeting between the latter and Carter PAGE, of US Republican candidate’s foreign policy team, in Moscow in July 2016. The secret meeting had been confirmed to him/her by a senior member of SECHIN’s staff, in addition to by the Rosneft president himself. It took place on either 7 or 8 July, the same day or one day after Carter PAGE made a public speech to the Higher Economic School in Moscow.
In terms of the substance of their discussion, SECHIN’s associate said that the Rosneft president was so keen to lift personal and corporate western sanctions imposed on the company that he offered PAGE/TRUMP’s associates the brokerage of up to a 19 percent (privatised) stake in Rosneft in return. PAGE had expressed interest and confirmed that were TRUMP elected US president, then sanctions on Russia would be lifted.

That is a particularly serious claim, that Sechin offered Page vast sums of money to put an end to U.S. sanctions, and that Page was interested, and that Page informed the Russians Trump would end sanctions on Russia if elected.

Is that really true? To vouch for the claims’ accuracy, Stephens referred readers to a piece by former CIA official John Sipher in a journal called Just Security, in which Sipher, Stephens’ words, “laid out the decisive case for their broad truthfulness.”

Here is what Sipher wrote about the Page trip to Moscow:

We learned that when Carter Page traveled to Moscow in July 2016, he met with close Putin ally and chairman of the Russian state oil company, Igor Sechin. A later Steele report also claimed that he met with Parliamentary Secretary Igor Divyekin while in Moscow. Renowned investigative journalist Michael Isikoff reported in September 2016 that U.S. intelligence sources confirmed that Page met with both Sechin and Divyekin during his July trip to Russia. What’s more, the Justice Department obtained a wiretap in summer 2016 on Page after satisfying a court that there was sufficient evidence to show Page was operating as a Russian agent.

In that passage, Sipher pointed to this Isikoff article, from Yahoo News, on September 23, 2016. The only problem is, Isikoff did not report that U.S. intelligence sources had confirmed the Page meetings in Moscow. In fact, Isikoff’s article was worded carefully to avoid saying that there had been any confirmation.

The article began by reporting that “U.S. intelligence officials are seeking to determine whether” Page met with the Russians. Isikoff noted that, at the time of his visit, Page had declined to say whether he met with any Russian officials. And then:

But U.S. officials have since received intelligence reports that during that same three-day trip, Page met with Igor Sechin, a longtime Putin associate and former Russian deputy prime minister who is now the executive chairman of Rosneft, Russian’s leading oil company, a well-placed Western intelligence source tells Yahoo News. That meeting, if confirmed, is viewed as especially problematic by U.S. officials because the Treasury Department in August 2014 named Sechin to a list of Russian officials and businessmen sanctioned over Russia’s “illegitimate and unlawful actions in the Ukraine.” (The Treasury announcement described Sechin as “utterly loyal to Vladimir Putin — a key component to his current standing.”) At their alleged meeting, Sechin raised the issue of the lifting of sanctions with Page, the Western intelligence source said.
U.S. intelligence agencies have also received reports that Page met with another top Putin aide while in Moscow — Igor Diveykin. A former Russian security official, Diveykin now serves as deputy chief for internal policy and is believed by U.S. officials to have responsibility for intelligence collected by Russian agencies about the U.S. election, the Western intelligence source said.

Contrary to Sipher’s claim, Isikoff did not report U.S. intelligence agencies confirmed reports about Page — he reported they had received reports about Page. That’s a pretty big difference. And just to emphasize the point, Isikoff wrote the alleged Page-Sechin meeting, if confirmed, would be important. (Isikoff also referred to the alleged Page-Sechin meeting as an “alleged meeting.”)

And yet now, somehow, Sipher’s article, with its mischaracterization of Isikoff’s reporting, is being cited as the “decisive case” for the dossier’s accuracy.

Also, where did the Page allegation in the Isikoff article originate? In the dossier itself. First, we know that Steele took the dossier to the FBI. Then we know that, at Fusion GPS’s direction, Steele personally briefed Isikoff on the dossier’s claims.

Voila: Isikoff reported, accurately, U.S. intelligence agencies received intelligence reports on Page’s trip. The alleged actions involving Page that Isikoff reported — attributed to a “Western intelligence source,” which was some reporters’ shorthand for the former British spy — lined up precisely with the contents of Steele’s dossier. (Even John Sipher conceded that, “Admittedly, Isikoff’s reporting may have relied on Steele himself for that information.”)

Given all that, Stephens’ point that the dossier “checks out” is basically saying the dossier proves the dossier.

For his part, Carter Page has repeatedly denied, most recently in testimony last week before the House Intelligence Committee, that he met with Sechin or Divyekin. Just did not happen, Page has said. (Page, who always refers to the dossier as “the dodgy dossier,” is also suing Yahoo News over the Isikoff report.)

Now, look for Democrats to point toward other Russians Page actually did come into contact with in Moscow. Page apparently did have some brief interaction with Arkady Dvorkovich, a deputy prime minister (an interaction that has been reported in the press), and Andrey Baranov, an official at Rosneft whom Page said was an old friend. Neither man is in the dossier.

By the way, both Stephens and Sipher repeated, as if it were accepted fact, a discredited talking point about Russia, Trump, and the Republican 2016 platform.

One more thing: Whatever else it was, Steele’s decision to take the dossier to the FBI was a brilliant marketing move, because it gave a crucial hook to reporters covering the Trump-Russia affair.

Unable to verify the dossier, those reporters wouldn’t have reported on Steele’s allegations by themselves. (Well, everyone except Mother Jones’ David Corn, who was also briefed by Steele at Fusion GPS’s direction and in October 2016 reported a “former Western intelligence officer” had “provided the [FBI] with memos” on the Trump-Russia matter.)

But giving the dossier to the FBI allowed reporters to say U.S. officials had received allegations about Trump — thereby giving an official imprimatur to the dossier.

The same happened when the FBI’s then-director, James Comey, informed President-elect Trump about the dossier in January of this year.

“The [intelligence community] leadership thought it important, for a variety of reasons, to alert the incoming president to the existence of this material, even though it was salacious and unverified,” Comey told the Senate Intelligence Committee in June. Among those reasons, Comey added, was “we knew the media was about to publicly report the material.”

As it turned out, the fact that Comey told Trump about the dossier gave the media the hook it needed to report on the document. Unable to verify the dossier, none, other than Corn, had reported its existence. But the fact that the head of the FBI informed the president-elect about the dossier — that was news. And that was indeed the hook the media used to report the existence of the dossier. From there, it was just a short hop to Buzzfeed publishing the dossier itself. Comey’s action moved things along.

And now, with the dossier fully public, some are caught up in a circular argument in which they cite the dossier’s allegations as proof that the dossier is accurate. All the more reason for investigators to tell the public everything they know about the dossier as soon as possible.