Should I Buy It?
We know what we should do. And yet, at the critical moment, we do something else. The commitment device is the answer to this problem: instead of relying on willpower in the moment, you make a decision in advance that makes the wrong option difficult or impossible.
Origin
Thomas Schelling, economist at Harvard and 2005 Nobel laureate in economics, formalized the concept in 1978 in Micromotives and Macrobehavior. His core insight: we are not a single coherent “self” — we are at least two. The cold, rational self that plans. And the hot, impulsive self that acts in the moment.
These two selves have different preferences. The commitment device is the tool by which the cold self constrains the hot self — before the latter takes over.
The oldest example comes from Homer. Odysseus, knowing he won’t be able to resist the Sirens’ song, has himself tied to the mast of his ship. He doesn’t count on willpower in the moment — he makes it irrelevant.
The Theory
The fundamental problem the commitment device solves is called temporal inconsistency. In theory (cold state): “I’m not going to buy this thing I don’t need.” In practice (hot state, facing the “Buy Now” button): click.
The gap between these two states isn’t a moral failing — it’s a basic property of the human brain. The limbic system (emotions, impulses) reacts faster than the prefrontal cortex (planning, long-term reasoning). Temptation exploits this speed gap.
The solution isn’t to “want harder.” It’s to change the conditions under which the decision is made — by increasing the cost of the wrong option or making the right option automatic.
Intensity Spectrum
| Level | Mechanism | Example |
|---|---|---|
| Soft | Added friction | ”Do you really want this?” overlay before purchase |
| Medium | Imposed delay | ”Come back in 48h to confirm” |
| Strong | Real cost | Money automatically lost if rule is broken |
| Extreme | Impossibility | Locked savings account, Odysseus’ mast |
In Practice
The simplest examples are the most effective:
- Alarm clock across the room: makes snoozing physically costly — you have to get up to turn it off.
- Credit card in a separate drawer: adds 30 seconds of friction to online impulse purchases.
- 24-hour delay rule: any purchase above a certain threshold waits overnight before confirming.
- Locked savings account: impossible to withdraw before a set date — the decision is made once, your future self can’t undo it.
Should I Buy It (Chrome extension) is a software commitment device: it intercepts the “Add to Cart” button before the impulse becomes an action, asks a few questions, and tracks decisions to reveal monthly patterns.
Economists Dan Ariely and Klaus Wertenbroch (2002) studied self-imposed deadlines in an academic context: students who set their own intermediate deadlines (with penalties) performed better than those given complete freedom — even when the deadlines were arbitrary.
Nuances and Limits
A commitment device is not a universal solution. Several limitations to keep in mind:
It must be set up in a cold state. The main difficulty is that you only think about protecting yourself when you don’t need to — and you forget to do it when you actually would need it.
It can create a rebound effect. If the device is too constraining or perceived as external (imposed by someone else), it can generate resistance and compensatory behavior (“I followed my rule all week, I’m giving myself a day off”). Effectiveness is highest when the rule comes from yourself.
It doesn’t address the root cause. A commitment device manages the symptoms of temporal inconsistency, not its source. It works best for behaviors with delayed consequences — impulse purchases, procrastination, bad eating habits — but is less useful for deeper issues (anxiety, lack of clarity about goals).
Sources: Schelling, T. C. (1978). Micromotives and Macrobehavior. Norton · Ariely, D. & Wertenbroch, K. (2002). Procrastination, Deadlines, and Performance. Psychological Science, 13(3) · Thaler, R. & Sunstein, C. (2008). Nudge. Yale University Press