Investigating money in politics is a little like studying dark matter: we have to make inferences about what we can’t detect from the behavior of things that we can see. While the “visible” universe of money in politics—mandatory disclosure of campaign contributions, some types of election spending, and lobbying—is sizeable in its own right, it represents only a fraction of the money spent on influencing government. Ken Silverstein’s recent e-book Pay to Play Think Tanks: Institutional Corruption and the Industry of Ideas (PDF) delves into the invisible world, demonstrating that influencers have plenty of other, less transparent tactics at their disposal.

Think tanks are not usually mentioned alongside super PACs and lobbying firms, but Silverstein argues that they are increasingly willing to help interest groups convert money into political power. Silverstein chronicles several of the most egregious cases: lobbyists who use their positions at think tanks to advance their clients’ interests, prestigious think tanks (including the Brookings Institution) that openly advertise their readiness to draw up custom research agendas for major donors, and “strategic partnerships” through which think tanks lend an aura of civic-mindedness to corporate donors, to name just a few. In the most egregious cases Silverstein cites, think tanks have even done complete about-faces on policy in apparent attempts to please clients, as when the Heritage Foundation went from criticizing the Malaysian government to touting it as a beacon of democracy once “Malaysian business interests” hired a consulting firm founded by Heritage’s president. Though Silverstein overstates his case when he claims that “the core policy options and alliances that shape American politics are simply dictated by the flow of cash”—for one thing, his own reporting shows that partisan and ideological loyalties often guide think tanks’ research and outreach—he makes a strong argument that think tanks are part of the money-in-politics complex (as have organizations, such as Transparify, that study think tank finances more systematically). How should we go about examining the role and importance of such diverse and opaque players in the influence game?

Step back and consider what (thanks to disclosure laws) we do know about money in politics. The 2012 congressional and presidential elections cost about $6.3 billion in reported spending, and state-level candidates raised another $3.1 billion (per the National Institute on Money in State Politics). About $3 billion in federal lobbying is disclosed every year. While these numbers appear large, they are small relative to the size of the U.S. economy, leading some political scientists to ask why, given the immense economic stakes, corporations and unions spend so little money on politics. Generally, they conclude that lobbying and donations matter at the margins but don’t determine policy outcomes all by themselves. Campaign contributions, for example, are not usually powerful enough to convince a congressperson to vote against his core ideology or his party’s line on a salient issue. Given that wealthy interests are still very good at getting their way, then, it makes sense to look at the aspects of money in politics beyond campaign contributions and lobbying to understand why.

Unfortunately, this is easier said than done, since money spent on political influence can take any number of forms, some relatively easy to investigate and others nearly impossible. The former include obviously political activities that are just barely concealed, such as the “issue ads” run by groups like Americans for Prosperity (part of the Koch brothers’ network). Given their focus on vulnerable Democratic senators, these ads are clearly intended to sway voters, but do not need to be reported to the Federal Election Commission because they avoid using words like “vote for” or “vote against” and run many months before Election Day. Journalists and other observers (including my colleagues at the Center for Responsive Politics) have made strenuous efforts to unearth and publicize this type of spending, but attempts to do so are always time-consuming and incomplete simply because the spenders are good at not disclosing anything unnecessarily. The ads’ existence is no secret, but their effect can’t be measured in any comprehensive way.

Silverstein makes the case that think tanks have strayed too close to the business and political spheres, risking credibility.

Somewhat harder to unearth are the wide variety of activities that are not disclosed because they fall just outside the technical definition of “lobbying.” If a lobbyist initiates contact with a congressional office, that activity has to be reported, but if the congressman calls up an old colleague (who now happens to work for a K Street firm) to ask for guidance, the latter doesn’t need to disclose the meeting even if the advice he gives helps his clients. A “government relations professional” who sticks to tactics like this one may not even need to register as a lobbyist. According to political scientist Tim LaPira’s estimate, D.C. lobbying firms employ almost as many “shadow” lobbyists as lobbyists that disclose their activities. Consequently, it seems likely that the recent decline in lobbying reflects money moving away from the light, not out of politics.

Even more difficult to study are the tactics that influencers use to set the terms of debate long before public officials are involved. Right now, for example, when I visit the New York Times’ site I see a banner ad by the “Regulation Resource Center” urging me to oppose a specific financial regulation. The Center is a project of MetLife, and the URL on the Times’ site indicates that the ad is part of a “DC Influencer Campaign”; anyone who rides the Washington Metro sees ads by unions and trade associations with the same goal. As Silverstein’s e-book demonstrates, think tanks have much more sophisticated means of facilitating access to “influencers”, such as luncheons or briefings sponsored by interest groups and attended by Hill staffers. As a result, those who can afford their services have a major advantage in setting the terms of debate on issues like Social Security and the deficit. While these tactics are not necessarily clandestine (and are typically well on the right side of the law), they tend to stay off the public radar.

In short, beyond the transparent world of money in politics exists a wide array of strategies that range from legitimate contributions to public debate to outright influence-buying. Where think tanks fall on this spectrum is not clear, and that ambiguity, argues sociologist Thomas Medvetz, is actually an indispensable part of think tanks’ influence. In Think Tanks in America (2012), Medvetz writes that think tanks are in a “quadruple bind,” simultaneously balancing their ties to the business, media, academic, and political spheres. A think tank that drifts too close to one of those spheres could lose its credibility, funding, or access to insiders. Silverstein makes the case that think tanks have strayed too close to the business and political spheres (he decries the “growing number” of “highly partisan think tanks” such as the Center for American Progress) and are weakening their credibility as a result. His brief discussion of the prehistory of the Washington think tank, which mentions the Brookings Institution and the Council on Foreign Relations, stresses that “the earliest were modeled on academic institutions and focused on technical aspects of policy”; without saying so explicitly, Silverstein implies that producing impeccably technocratic research was a more proper goal for think tanks than maximizing their press hits or disseminating partisan talking points.

Silverstein suggests disclosure as a remedy, arguing that think tanks should voluntarily publish their officials’ financial statements as well as their donor list, but provides little evidence that think tanks are worried enough about their credibility to do so. On the contrary, think tanks are probably more concerned about the loss of credibility that would come with disclosing donors and having the media and political opponents pore over the list for embarrassing details. Moreover, disclosure will do nothing to address Silverstein’s other concern, the transformation of think tanks from idea factories into partisan attack dogs. Medvetz’s argument suggests that think tanks simply have too much to gain by “binding” themselves—turning themselves into reliable sources for the media and allies for politicians—to care about the loss of their autonomy.

Enough bad publicity from embarrassing anecdotes like the ones Silverstein mentions could help shift think tanks’ incentives, perhaps making them marginally less likely to put out shamelessly partisan reports or hawk their services to interest groups. That would, in turn, slightly reduce money’s impact on political discourse, which would be a minor victory in itself. What it won’t do, however, is provide the kind of widespread transparency that we (mostly) enjoy in the realm of campaign finance—transparency that would help us understand how and to what extent money rules our political system. In its absence, scholars and watchdogs of transparency should do what we can with the data we have, while being aware that we are engaged in a drunkard’s search that may not always reveal the true patterns of power.