Why We Break Promises (and How to Keep More of Them)

We mean it when we say yes

Most broken promises are not lies. The person who agreed to send a quote by Friday meant it. The parent who promised to be at the school play, the freelancer who said a draft would be ready on Monday, the shop owner who told a customer the stock would arrive next week: each of them had a real intention at the moment they spoke. Something still went wrong.

Psychologists have a name for the gap between meaning to do something and actually doing it: the intention-behavior gap. In a 2016 review, Paschal Sheeran and Thomas Webb concluded that intentions turn into action roughly half the time. The gap is not simply a character flaw. It is a fairly predictable result of how people plan, and predictable problems can be designed around.

Three forces explain much of the story.

The planning fallacy: we are poor at estimating time

In 1994, Roger Buehler, Dale Griffin and Michael Ross described what they called the planning fallacy. People predict that tasks will finish sooner than they actually do, even when similar tasks ran late in the past. In one of their studies, university students predicted they would finish their honors theses in an average of 33.9 days. The actual average was 55.5 days, and only about 30 percent finished by their own best estimate.

The most useful finding was not that students were careless. Buehler's team found that people plan from the inside. They picture the steps of the current job and imagine things going smoothly. When participants were asked to think about how long comparable past projects had taken, their forecasts became more accurate. In one condition, about 60 percent of students finished on time, compared with about 29 percent in the control group. Memory of past delays was the missing ingredient.

Bent Flyvbjerg, who studies large infrastructure projects, makes a similar point from a different field. He describes optimism bias as the tendency to see future outcomes more favourably than past experience supports, and he links much of it to planners taking an "inside view" of their project rather than looking at how similar projects actually turned out. For a small business owner, the same mistake shows up as the sign-writer who promises a three-day job that always takes a week.

Optimism about the future

Promises are about the future, and the future always looks more manageable from the present. When we say yes, we tend to imagine the version of the week where nothing unexpected happens. The transport runs, the client replies quickly, the power stays on. Almost nobody writes the car breakdown or the afternoon the supplier is closed into the diary.

This matters because a promise is only as strong as the assumptions beneath it. If you say "I will deliver on Thursday" without allowing for a slow supplier, a sick day or a public holiday falling on Friday, you have made a promise with a hidden condition. You did not intend to break it, but you did make it fragile from the start.

There is also a social pull. Saying yes feels kind, and saying "I am not sure I can" feels like letting someone down. Sheeran and Webb note that goals driven by social pressure or obligation, rather than by personal belief, are less likely to be carried through. A promise made to end an uncomfortable conversation is often the first one to fall away.

The intention-behavior gap: a plan needs a trigger

Sheeran and Webb list several reasons intentions fail. Some sit in the intention itself: goals that are over-optimistic, goals that rest on social pressure rather than personal belief, and intentions that shift with mood. Others are about self-regulation: forgetting, procrastinating, being distracted by competing priorities, or falling back into habits that do not match the new goal.

Peter Gollwitzer and Paschal Sheeran reviewed a practical response to this in 2006. Their concept of an "implementation intention" is an if-then plan that links a situation to a specific action, for example: "If it is Monday at nine, then I will send the invoice before I check my messages." Across 94 independent tests, they found a medium-to-large positive effect on whether people reached their goals. The tool is simple, and it works because it moves the decision out of the moment of temptation and into the plan.

Practical ways to keep more of your word

Make the promise specific. "Soon" is not a deadline. "By 4 pm on Thursday" is. Describe what done looks like, so that both sides agree on the finish line before the work starts.

Plan the when and the where. Attach the promise to a time slot or to a routine you already have, such as after the morning team call or when you open the books on Monday.

Estimate from the past. Before you commit, ask how long the last three similar jobs really took, including the messy parts. Use that number as your starting point, not the number you wish were true.

Leave a margin for the unexpected. If a deliverable depends on someone else, build in a day or two of slack. A buffer is not pessimism. It is the honest acknowledgement that other people and other weeks exist.

Say the risk out loud. If you can see a problem coming, tell the other person early. A changed date with a clear reason is far easier to live with than a silence that ends in a missed deadline.

Write it down and share it. A promise held only in your head is easy to shift. A promise written down, with a date and the other person's acknowledgement, is much harder to forget or quietly reinterpret.

A tool like Promikept helps with that last step. You can record a promise with its date, seal it so the other person sees the same wording, and keep a running list of what is still open. The point is not to police anyone. It is to make sure both people are working from the same version of the commitment, which is where many broken promises begin.

Review your promises once a week

Most people make promises in bursts and then lose track of them. A short weekly review helps. Set aside fifteen minutes, list every commitment you have made that is still open, and ask three questions. Is the date still realistic? Do I have the next step scheduled? Does anyone need to hear about a change from me this week?

This habit does two things. It catches slipping promises while there is still time to renegotiate them, and it trains you to notice the gap between what you said and what your calendar says. Over a few months, the difference in reliability can be noticeable, even though the underlying skills are simple.

A note on what research can and cannot promise

These findings describe tendencies across many people, not guarantees for any one person. Individual results vary, and a good system will not stop life from interrupting. What the research does suggest is that planning for how things usually go, not only for how we hope they will go, gives promises a more realistic footing.