As the impeachment inquiry heats up, members of Congress and the media are left with the difficult job of untangling the conspiracy theory that seems to have driven the president’s actions in Ukraine: a wild tale of a missing computer server whisked off to Eastern Europe for nefarious, if never entirely clear, purposes, and something involving Joe Biden, his son Hunter and, for good measure, China, too.

Although a strong vein of conspiratorial thinking courses through the right today, dismissing conspiracy theories as a recent product of the “paranoid style” of the American right underestimates their influence on our political culture as a whole. Just last week, for example, Hillary Clinton claimed without evidence that the Russians were grooming Democratic presidential candidate Tulsi Gabbard for a third-party run aimed at damaging the eventual Democratic nominee.

Seeing the full ideological array of conspiratorial thinking and understanding its deep history are essential to understanding how paranoid thinking about Russian conspiracies, which so troubled the McCarthyites in the 1950s and 1960s, could jump from right to left in the wake of the 2016 election.

Conspiracy theories — or allegations that secret agents were working together for a hidden (typically sinister) purpose — are older than the nation, and have been voiced by every party that ever took part in the country’s politics.

The paranoid style in American politics, a phrase coined by historian Richard Hofstadter, originated from the 18th-century political ideology of republicanism, which viewed power as ambitious and grasping and accordingly saw liberty as always on the defense. Republican fears of power’s expansionist tendencies spurred the revolutionary generation to regard British taxation after 1763 as not simply a deviation from prior norms, but as the first step on a swift descent toward political enslavement. American revolutionaries were not simply whiny about taxes; they were paranoid.

Winning independence didn’t soothe their anxieties.

The first bipartisan political divide in the United States emerged from conspiratorial anxieties. In the 1790s, conservative Federalists worried that their more democratic Jeffersonian rivals wanted to bring French-style revolution to the United States. At their most extreme, archconservatives such as Timothy Dwight warned that Jeffersonians were under the sway of the Bavarian Illuminati, an international conspiracy aiming to overthrow Christianity.

The Jeffersonians claimed that the Federalists were conspiring to destroy the republic and erect an aristocracy in the United States. The degree to which either side believed what they were saying about their rivals has been hotly debated by historians ever since. Did Federalists just use the specter of the Illuminati to tar their rivals? Or did they mean it? Did the Jeffersonians really think the Federalists were conspiring to bring back monarchy as they alleged? Or were they just trying to win elections? The answer depends on who and when, but it’s safe to say that some did believe these theories.

American partisans continued to find conspiracies at work throughout the 19th century. Supporters of President John Quincy Adams (Adams’s son) believed that a secret cabal had contributed to Adams's 1828 defeat at the hands of Andrew Jackson. The author of an 1835 political history of Jacksonianism warned on the first page, “We are admonished by history, that the principal dangers to popular governments arise from the interference of foreign nations, either by force or fraud, in their concerns; or from the corrupt ambition of their own citizens seeking exclusive and forbidden powers.”

But this conspiracy theory itself spawned others: One angry reader accused the book of being “a hodgepodge of misrepresentation + invective,” written by “the most abandoned malignant slanderers ever sold to perdition.” To this reader, the book must have been “brewed in Wall-street, that hotbed of bank tyranny.” Only a conspiracy, ginned up for partisan effect, and personal profit, could have led to such ideas about Jackson.

Conspiracy theory after theory, Americans cast a paranoid eye on their partisan opponents throughout the 19th and 20th centuries. According to the Oxford English Dictionary, the phrase “conspiracy theory” first appeared in the early 20th century United States, in the context of political histories of the 19th century. The phrase increased in popularity during the McCarthy era that inspired Hofstadter to coin the term “paranoid style” during lectures he gave at Cambridge University in 1958 and 1959 and expanded upon the concept in a November 1964 essay in Harper’s Magazine on the rise of the far-right wing of the Republican Party.

Democrats’ anxieties about Russian conspiracies to interfere in the 2016 campaign cannot be extricated from this historical context of paranoia just because they have a significant basis in fact. As Joseph Heller wrote, “Just because you’re paranoid doesn’t mean they’re not after you.”

Now Democratic charges of a Russian conspiracy have provoked Republican countercharges of a Ukrainian conspiracy tied to former vice president Joe Biden. This new conspiracy theory, which makes false claims about the vice president’s interference in Ukrainian politics to protect the business interests of his son, appears to skeptics to be the malicious invention of Republican political hacks, designed to weaken Biden’s presidential candidacy.

According to recent reporting, tales of corruption by Biden and his son Hunter originated with Peter Schweizer, a conservative writer and editor at large for Breitbart. Schweizer is also president of the Government Accountability Institute, an opposition-research operation founded by Stephen K. Bannon and funded by the billionaire hedge-fund magnate Robert Mercer, President Trump’s largest contributor. Schweizer is a longtime pusher of conspiracies about liberals. He published a book in 2018 titled “Secret Empires,” which included a chapter about the Bidens in Ukraine.

The most eager consumer of this new Ukrainian conspiracy theory featuring the Biden family has been Trump, who has endangered his own presidency with his efforts to promote it. With Trump’s apparent approval, his personal lawyer and political operative Rudolph W. Giuliani has not only worked with journalist John Solomon, a former Washington Post writer who was just hired by Fox News Channel, to spread the story, but also with two Soviet-born business executives, Lev Parnas and Igor Fruman, to encourage Ukrainian connections to generate more information to feed the conspiracy theory.

Some commentators view Trump as breaking from the past, with his ready willingness to fuel conspiracy theories to motivate voters to support him and his party. They point to how much this diverges from presidents in recent decades.

But a more nuanced appraisal would situate Trump in the long history of peddling conspiracy theories in American politics. Instead of representing a massive departure, Trump’s deviation from the past is far more slight: He’s conspiracy mongering while his party largely controls power. Typically it is members of the party out of power who push conspiracies.

The republican political theory underlying the American paranoid style had its origin in the writings of opposition politicians in 18th-century Britain. Since then, conspiratorial thinking, has remained most attractive to opposition parties seeking to discredit their establishment rivals. This is the nature of Trump’s criticism of Democratic investigations of Russian conspiracies to hack the 2016 campaign. They’re just whining because they lost, Trump has said repeatedly.

This may be the norm, but Trump’s ongoing embrace of conspiracy theories while in office can still be explained by the history of political conspiracy thinking. When parties in power — like the Federalists in the 1790s — start to feel their grasp on power slipping, they, too, travel down the road of conspiracy peddling.

And today, Trump and his supporters may be right to perceive themselves on the defense, as changing demographics and social norms make the ongoing domination of American politics by white men like themselves less assured. If Trump’s embrace of the Ukraine conspiracy doesn’t sink his political future by leading to impeachment, it may nonetheless signal that his political future is bleak.