Everyone Knows Money Influences Politics … Except Scientists Why is it so hard to prove something that’s common knowledge? And why try to do it in the first place?

The Affordable Care Act gave Amy McKay a chance to do something she never thought would be possible. It had nothing to do with her health care. The only pre-existing condition McKay was worried about was metaphorical, an infection colonizing the body of the federal government.

A political scientist who studies the way companies and interest groups influence policymaking, McKay was searching for an answer to a fundamental question of politics: Does money matter? Could making a donation to a politician before he’s elected buy you a favor once he’s in office? The answer seems obvious, but for decades, political scientists had struggled to find a definitive answer. McKay was part of a cadre of researchers convinced it would be possible to reach a well-supported conclusion — if you found the right data to study. In the fall of 2009, as the ACA took shape in the Senate Finance committee, she found her way in. Reams of data that no academic had gotten their hands on before was suddenly available to her. Ten years of database wrangling later, McKay published a study that experts say is probably the best evidence we have that money really does influence political decision-making.

It was a long struggle and a big achievement. It was also a whopping anticlimax. Are you shocked to find out that there’s evidence suggesting campaign donations have power in the halls of congress? I wasn’t. Nor, likely, were the 72 percent of Americans who already believe their federal political system is tainted by filthy lucre.

If anything, what’s surprising here is that we didn’t already know this for sure. Despite the topic being the subject of vigorous legal and political debate, despite the fact that most Americans believe it’s happening and see it as a problem, despite the testimony of politicians themselves, decades of research haven’t been able to conclusively prove that money buys influence. McKay’s study doesn’t even put an end to this strange lacuna in political science. She herself acknowledges that it isn’t a smoking gun. McKay took on a challenge. She succeeded. She ended up more cynical.

This is not a straightforward or uplifting story, I know. Tracing the path of rot that money eats through Congress isn’t as easy as diagnosing a fractured bone or a pneumonia-ridden lung. Instead, experience tells us the rot exists, but evidence can’t pin it down. Attempting to prove it’s real can feel futile. Failing to prove it can feel like madness. It’s more like having chronic fatigue syndrome, a disease that leaves your body wrecked while doctors argue over whether it’s all in your head. The Affordable Care Act gave McKay access to evidence that suggests money influences politics. But it also presented a new challenge: Does evidence matter when it tells us something we’d already thought was true?

The Senate Finance Committee entered its chambers on September 22, 2009, carrying the rough pattern for a bill that would become the Affordable Care Act and 564 amendments that various committee members were hoping to tack onto it. Like seamstresses, pins in their mouths, the senators cut and hemmed, tapered and lengthened. Each alteration shaped the bill, altering which health care costs Americans could expect to have covered, which companies would supply that care, and what fees consumers would pay. Ten days later, they emerged with something more akin to a tailored suit — one bill with 41 amendments, sent off for the full Senate to try on.

Behind every piece of legislation is a complex design process that voters — and researchers — seldom get to see. The public face of lawmaking (and the easily accessible public record it leaves behind) is largely centered on the roll call vote — the final yeas and nays that decide whether a bill is voted into law or rejected.

Those votes have been the focus of much of the research concerning money and politics, and they suggest that there’s not much to find. More than 40 years of study has largely failed to turn up strong correlations between monetary donations and the outcomes of those votes, said Stephen Ansolabehere, a professor of government at Harvard.

“If you can’t eat their food, drink their booze, screw their women and then vote against them, you have no business being up here.”

The late California state assemblyman Jesse “Big Daddy” Unruh is said to have put it more bluntly: “If you can’t eat their food, drink their booze, screw their women and then vote against them, you have no business being up here.” That’s bravado, but the sentiment is basically accurate, said Jim McDermott, who represented Washington’s 7th Congressional District for nearly 30 years. He told me there’s never going to be a straight line between a $5,000 donation and a decision to vote yes or no.

Partly that’s because there are lots of competing pressures attached to both roll call votes and campaign donations. People donate to politicians who already share their views. Politicians are already primed to be concerned about business issues that affect the economy in their district, and the same politician may have multiple donors taking opposite sides on the same vote. Meanwhile, roll call votes are very public things. Your party expects to see certain choices. So do your constituents. Money isn’t the only thing legislators are thinking about when their names are called. McDermott and other politicians I spoke to said they remembered voting against the interest of donors — some of whom donated again later on.

But there are many ways to influence legislation beyond dictating whether someone votes yes or no. Those decisions are tiny stitches, largely invisible in the finished bill. The problem for researchers is there’s seldom a record of those small alterations. But to some political scientists, this was the absence of evidence, not evidence of absence. “A lot of us couldn’t accept that money didn’t have any effect in politics,” McKay said.

The ACA was different, however. Politicians were eager to avoid the political debacle of the 1990s’ attempts at health care reform, when the White House was perceived as having handed down ready-to-wear legislation, rather than allowing Congress to tailor a bill to its liking. That led legislators to take rare steps to make the 2009 bill-writing process more transparent. Sen. Max Baucus, then chairman of the Finance Committee, published the full text of every single proposed amendment on the committee’s website. Meanwhile, McKay was serving as an American Political Science Association congressional research fellow, a program that placed her on the staff of another Finance Committee member. The position gave her access to the text of public comments submitted to the committee. That’s a big deal. Public comment is a formal process, a period where anyone can tell the senators what they want to see in the final bill. That meant big donors, corporations and lobbyists were all submitting letters highlighting the issues they thought were most important. Usually, those letters aren’t accessible to researchers, McKay said. Because she was in the right place at the right time, she collected them all.

Then she started trying to see how the comments shaped the proposed amendments. She used plagiarism-detection software, like the kind professors use to spot cheating undergrads, to match text from public-comment letters with text in amendments. When she found text that appeared to have been copied from one to the other, she checked whether those comments were linked to any political donations. A separate database compiled by the nonprofit Sunlight Foundation kept a record of fundraising events hosted by lobbyists and donors. Essentially, McKay used the letters, amendments and campaign finance records to follow a trail: from fundraising to fundraisers’ suggestions for the bill to amendments based on those suggestions.

The paths she found were clear. Not all the matched amendments came from groups that had hosted fundraisers. Not all the fundraising hosts got a matched amendment for their efforts. But hosting a fundraiser turned out to increase your chances of getting your words in a proposed amendment — hosts’ letters were three and a half times as likely to text-match with amendments as non-hosts’.

Roll call votes suggest politicians can successfully live by the philosophy of Big Daddy Unruh. But McKay’s study suggests that the relationship between money and policy is more in line with former Congressman Barney Frank’s blunt assessment: “We would be the only human beings in the history of the world who, on a regular basis, took significant amounts of money from perfect strangers and made sure it had no effect on our behavior.”

But didn’t we all know that already?

“It is kind of a ‘duh,” said Eleanor Neff Powell, a professor of political science at the University of Wisconsin-Madison. She’s one of many researchers who have found evidence that money and politics are linked, just like American voters always suspected. McKay isn’t the first scientist to show that the two forces connect outside the roll-call vote. Since the 1980s, research has established that interest groups are more likely to get their way in votes where there’s less public attention or debate, has found that companies that spend money on lobbying and campaign contributions do better financially, and has documented experimentally that groups identifying themselves as donors have an easier time getting face-to-face meetings with members of Congress and their high-level staffers.

What’s more, politicians will readily admit to the kind of thing McKay and others have found. Baucus, the Senate Finance Committee chair whose transparency made McKay’s work possible, was unsurprised to find that text from lobbyist letters ended up in his bill. “I’ve seen that happen from the get-go, from when I first arrived in Congress,” Baucus said. “But so what?” It’s not illegal.

The Supreme Court has established a precedent where the government can only ban a very specific type of corruption. If a donation can’t be shown to have been taken by a politician in exchange for an altered vote or other political favor, it’s not a bribe and so should be allowed, the court ruled. Powell and McKay both told me they hoped that proving money was shaping policy would convince the courts to overturn past rulings and allow tighter regulation of campaign finance. But that’s unlikely when what their research has proven is happening isn’t something the court sees as corrupt, legal experts told me. And all of this can make both McKay’s study and the whole process of accumulating evidence to identify and fix a problem in society — the entirety of social science, if you will — feel futile and broken. What’s the point of evidence if it proves something most people already believe and doesn’t change anyone’s behavior?

That depends on what you expect evidence to do for you, said Lawrence Lessig, a law professor at Harvard whose work focuses on campaign finance law. Research like McKay’s can’t change campaign finance law, he said, because the problem is philosophical. It’s in the heart, not the head. Instead, he told me, the value of evidence is in the way it helps craft new philosophical appeals. Hard facts can’t solve the problem, but maybe they can shape the emotional appeals that do.

In theory, evidence ought to put an end to arguments. Two people disagree, and the one with the evidence wins. The problem is solved. But that’s not really the norm, especially in the realm of politics. What McKay and Powell hoped would happen — judges see new evidence of money influencing politics and say, “Oh, maybe the money should be better regulated” — represents the theory of evidence-based decision-making. Lessig, in contrast, is more of a believer in realpolitik. If evidence can’t win an argument, maybe it’s time for a new argument entirely.

“They aren’t troubled by the fact that money influenced policy,” Lessig said of the Supreme Court justices who voted to define corruption very narrowly in cases like Citizens United v. Federal Election Commission. In that case and others, the justices said that only red line is if a politician accepts a bribe. Any other kind of monetary donation is just someone presenting their ideas, and politicians have a right to consider those ideas. From the conservative Supremes’ point of view, proving that money influences policy is just proving that democracy is happening. So instead, Lessig wants to use the evidence to build a philosophical case in favor of a new definition of corruption.

“A world where you have to spend half your time raising money means there’s this small number of people on whom you’re dependent and they have a huge influence.”

To him, evidence like McKay’s can’t demonstrate that corruption is unequivocally happening, but it can demonstrate that money has a subtle influence, even an unintentional one, over the whole system of government. And if that’s true, then maybe bribing an individual should be thought of as something separate from corruption. “A world where you have to spend half your time raising money means there’s this small number of people on whom you’re dependent and they have a huge influence,” he said. That, according to Lessig’s worldview, represents a corruption of how our government was intended to function. The evidence doesn’t win the argument over whether we need stricter campaign finance laws. But it does help build a philosophical case that maybe we should be thinking about influence in a different way.

It’s not clear if this is a slam dunk. Lessig is currently testing his argument out in a campaign finance case that began in Alaska, where, according to the lawsuit, state-imposed caps on political donations have been routinely ignored by corporations and unions since the 2010 Citizens United ruling. He expects it to eventually end up before the Supreme Court.

Regardless of what happens, though, his strategy demonstrates why evidence can matter, even if what it proves is no surprise. When experts in evidence-based policy say we need to think more broadly about what that means, they’re talking about situations like this.

Evidence-based decision-making, as a movement, grew out of the medical field, said Paul Cairney, a professor of politics at Scotland’s University of Stirling who specializes in evidence-based policy-making. The people involved generally had a shared philosophy and were trying to solve relatively simple problems, such as whether Medication A works better than Medication B.

But in politics, things are different. You can start with data that shows money shapes policy and end up in a debate about how we ought to define corruption. Something similar happened in the national conversation about climate change, where scientists accumulated fact after fact, stacking the data in front of powerful people and hoping it would change the course of policy. Instead, the country ended up in a debate about what sound science is. In each case, debates over policy ended with scientists learning, to their dismay, that you can’t bring a fact to a philosophy fight.

McKay told me she used to believe Congress was essentially honest — the data changed her mind. But McKay is a researcher, not a politician. While the Supreme Court may be coming to the question from the same starting point as McKay, the data alone is unlikely to sway them. It seems like a simple question: Does money influence politics? But trying to answer it quickly becomes an object lesson in how hard it can be to convince someone of the obvious.

Likewise, our question is deceptively simple: Does a discovery matter if it tells you something you already knew? Maybe, if it means you’re forced to engage with the deeper, philosophical quandaries that made people ask the question in the first place. Sometimes, the answer depends on more than evidence. It depends on what you meant by the question.

CORRECTION (June 4, 2019, 9:11 a.m.): An earlier version of this article misidentified the location of the University of Stirling. It is in Scotland, not England.