Volunteer’s Dilemma, explained.
The Volunteer's Dilemma occurs when everyone benefits if at least one person takes a costly action, but each person would prefer someone else to bear the cost.
Why it happens
Waiting may work if someone else acts. When everyone reasons that way, the necessary action can remain undone. Larger groups create more possible volunteers but can also change each individual's willingness to take responsibility.
Diekmann's volunteer dilemma shows how a public good can remain unprovided when each person hopes someone else bears the cost.
Read the result
Change group size and each other person's assumed volunteering chance separately. More people raises the chance that somebody acts when that individual probability is fixed; real probabilities need not remain fixed as groups grow.
A worked example
Someone needs to report an outage
Five people notice a shared problem that one report could fix.
Each assumes someone else will report it, so everyone may wait despite wanting the repair.
An explicit assignment can resolve uncertainty about responsibility without requiring every person to duplicate the task.
OPTIONAL DEEPER DETAILGo deeper: inside the model
Inside this model
The benefit is 30 if at least one person volunteers. A volunteer receives 30−cost. Waiting yields 30 with probability 1−(1−p)^(group−1), otherwise zero. Playing samples each of the other group members independently.
Where this idea is useful
A practical use
When a shared problem needs one person to report it or organize a fix, everyone may wait despite valuing the result.
A common misconception
“A larger group always means the task will be done.”
That follows only under specific assumptions about individual behavior. If willingness falls with group size, the overall result can differ.
What this explanation leaves out
- This assumes identical benefits and independent fixed probabilities. Social roles and coordinated commitments can change real behavior.
How is this different from a threshold public good?
The volunteer model needs at least one action rather than a total funding level. It highlights responsibility and the personal cost of being the actor.
Has responsibility been assigned, or is everyone assuming someone else will act?
Further reading
Explore the original research or the teaching reference behind this experiment.