In this time of April, when most people think about taxes it involves making sure they get filed, as well as how much you owe (or are owed by) the government. But taxes can also play a crucial role in electoral politics. Generally, we tend to think of taxes as one of (if not the paramount) issue on which voters are able to judge which party’s policy proposals are closer to their own.

New research by political scientists Michael Tomz and Robert Van Houweling, however, also illustrate that taxes can become closely linked to electoral politics through another mechanism: the “political pledge”, best exemplified by Grover Norquist’s anti-tax pledge. Here’s the abstract from their paper:

How can interest groups secure credible policy commitments from politicians? Previous research has argued that groups screen politicians to identify true believers, and they enforce commitments through repeated interactions. We argue that political pledges provide another solution to the commitment problem. Pledges tie the hands of politicians by involving voters in the enforcement process. If politicians violate a group’s pledge, even voters who disagree with the pledge will carry out a punishment. Using survey experiments, we show that the “No New Taxes” pledge commits signatories by significantly increasing the electoral cost of advocating higher taxes. We also explain how the pledge incentivizes even nonsignatories to avoid raising taxes. By deterring politicians from responding to changes in public opinion, pledges can contribute to non-representative policies.

Ezra Klein has a more detailed summary of the paper’s argument and key findings on his blog at the Washington Post, so I won’t repeat that here. Klein is to be commended (once again) for highlighting political science research, but he also gets some kudos here for zeroing in on one of the questions faced by all survey experiments (even though he doesn’t explicitly use the political science lingo): external validity. Klein writes:

But Tomz and van Houweling are presenting a world in which voters know nothing about the candidate save for the pledge. In the real world, voters know quite a lot about candidates — particularly incumbents — and so they base their votes on a multitude of factors. Someone like [Senator] Coburn, who has a strong personal connection with his constituents, might be able to survive breaking the pledge. But weaker incumbents probably don’t want to risk it. And unknown candidates who run in primaries can’t resist it. And so the pledge endures.

I suspect Klein is correct that the cost to candidates for breaking these kind of pledges is not the same in all cases. Tomz and van Houweling – as they have in previous work – keep their parties anonymous (“Senator A” and “Senator B”). So the experiment as currently designed is not going to be able get at the question Klein raises: does someone like Sen. Coburn have enough capital banked with his voters to be able to get away with breaking the pledge in a way that other legislators do not? (A nice extension of this question in a comparative context could be whether some parties in multi-party systems are better able to get away with breaking campaign promises than other parties). That being said, Tomz and van Houweling do close the paper with a strong claim that could be read as denying that Klein’s point will ever really matter (see p.30):

Our experiments suggest that signatories would almost never find it electorally optimal to break the “no new taxes” pledge [emphasis added]. Remarkably, the pledge binds even during periods of national crisis, when economic and political circumstances might tempt signatories to renege. We ran our experiment at a time when Washington was focused on the skyrocketing debt, ratings agencies were threatening to downgrade U.S. government bonds, and bi-partisan commissions were arguing that tax increases would be necessary to solve the crisis. We also ensured, in our scenarios, that new taxes would be paired with spending cuts and devoted to deficit reduction. Even in these extenuating circumstances, the pledge strongly tied the hands of politicians.

Klein does raise the issue of whether if the entire Republican party decided to defect from the pledge en mass (say as part of a hypothetical grand-bargain on deficit reduction) it might somehow provide cover to the legislators as individuals. From a game theoretic standpoint, though, we might wonder whether we would ever get to such an outcome in the world described by Tomz and van Houweling. Since the punishment from breaking the pledge can come from primary challengers, any attempt to craft such a grand bargain that broke the pledge would run up against a prisoner’s dilemma: even individual legislators who favored the grand bargain would be better off letting it pass without their vote, so as to better forestall a primary challenger in the future. This viewpoint is consistent with a final piece of anecdotal evidence offered by the authors (p.31):

Consistent with our findings, many participants in the 2011 standoff over national debt claimed that the pledge prevented Congress from reaching a compromise that included revenue increases as well as spending cuts. Majority Leader Harry Reid (D-NV) argued on the Senate floor that Republicans were “terrified to violate the infamous Grover Norquist tax pledge,” and former Senator Alan Simpson (R-WY) added that many Republicans in Congress felt “trapped” by the pledge.

The full paper is available here.

[Cross-posted at The Monkey Cage]

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Joshua Tucker is a Professor of Politics at New York University.