The starting assumption behind most jokes about politicians is that they say whatever gets them elected and then quietly abandon it once in office. The most direct test of that assumption comes from the Comparative Party Pledges Project, a research effort led by political scientists Robert Thomson, Terry Royed, and Elin Naurin, published in the American Journal of Political Science in 2017. The team tracked more than 20,000 specific campaign promises across 57 elections in 12 countries and checked, pledge by pledge, whether each one was fulfilled once the party held power. The result runs against the assumption: governing parties fulfilled a majority of their pledges, and in some countries the rate was strikingly high, more than 85 percent of pledges by governing parties in the United Kingdom were at least partly enacted. The rate was lower in coalition governments, where a party has to share power and compromise with partners, typically dropping to around half of pledges fulfilled. A separate look at one governing party’s manifesto found a real complication worth naming honestly: pledges that voters considered most important were somewhat less likely to be kept than minor ones, pulling an otherwise strong fulfillment rate down when weighted by what people actually cared about. Even accounting for that, the broad picture from the largest study of its kind is that most campaign promises, most of the time, are not simply abandoned.
If that is roughly true, it raises an obvious question: why does trust in politicians remain so low, and specifically low, compared to trust in other institutions? A large-scale study published in the British Journal of Political Science in 2025 by Viktor Valgarðsson, Will Jennings, Gerry Stoker, and colleagues, drawing on more than 3,300 surveys across 143 countries from 1958 to 2019, found that trust in elected representatives has been declining fairly steadily over that period, while trust in institutions that are not directly elected, such as the police, the civil service, and the courts, has stayed roughly stable or even risen. That distinction matters. The erosion of trust is not spread evenly across government. It is concentrated specifically on the people who make campaign promises in the first place.
Part of the explanation is psychological rather than political, and it does not require assuming politicians behave any differently from other people under similar incentives. One of the most heavily cited findings in psychology, from a 2001 review by Roy Baumeister, Ellen Bratslavsky, Catrin Finkenauer, and Kathleen Vohs titled “Bad Is Stronger Than Good,” is that negative information is processed more thoroughly, remembered more vividly, and weighted more heavily than positive information of equal size, across nearly every domain the researchers examined, from relationships to reputations to first impressions. Applied to politics, a broken promise or a scandal is a discrete, memorable, reportable event. A promise that was kept quietly, on schedule, without incident, rarely becomes a headline at all. The asymmetry is not that broken promises happen more often. It is that broken promises are simply more visible and more sticky in memory than kept ones, which are, by their nature, unremarkable.
There is also evidence that a single broken promise does more damage than its size alone would suggest, because that damage does not stay contained to the person who caused it. A 2026 study in Political Psychology by Jakob Schuck, Rainer Greifeneder, and Fanny Lalot followed more than 2,100 people across Germany, the United Kingdom, and the United States through multiple election cycles and found that when someone perceives a specific political betrayal, meaning a politician or party visibly violating a promise the public understood clearly, the resulting drop in trust does not stop at that individual or party. It measurably spreads to trust in other political figures and institutions that had no connection to the original broken promise. One politician’s bad behavior effectively taxes the reputations of politicians who did nothing wrong.
These four findings describe a specific and somewhat counterintuitive mechanism rather than a simple story about dishonest people seeking office. Most campaign promises are kept, according to the largest cross-national dataset built to check. Trust in elected officials specifically, not government generally, has still declined for decades. Human memory is well documented to hold onto broken promises and scandals far more tightly than kept promises, which never generate a story in the first place. And the damage from one broken promise does not stay contained to its source; it spreads across the wider category of “politicians,” lowering trust even in people and institutions that played no role in the betrayal.
None of this means political scepticism is irrational. Some promises are deliberately vague, some are impossible to deliver, and some are abandoned the moment they become inconvenient. The promises that matter most may also be the hardest to fulfil, particularly when governments face coalition partners, hostile legislatures, economic shocks, or circumstances that did not exist during the campaign. Voters are right to judge politicians by what they actually do rather than what they say.
But the evidence suggests that the popular belief that politicians almost never keep their promises is not an accurate summary of their record. It is closer to a summary of how political failure reaches the public: loudly, repeatedly, and with far greater emotional force than ordinary competence. A broken promise becomes proof of what politicians are like. A fulfilled promise becomes a policy that quietly exists, often without anyone remembering who promised it in the first place.
