The cost that never appears on the repair bill
A broken window creates visible work: someone must replace the glass, and the repairer earns income. But that transaction uses labor, materials, and money that could have gone elsewhere. To judge the economic effect, compare the repair not with doing nothing, but with the best purchase or investment that would otherwise have used those resources.
That missing alternative is an opportunity cost: the value of what is given up when a choice is made. The repair bill records the glass and labor purchased. It does not record the new coat, tools, or other goods the owner might have bought instead—or the work those purchases might have supported.
Why visible activity can mislead
The idea is often called the “broken-window fallacy,” an error of treating one visible benefit as if it were the whole result. After damage, the glazier’s business may gain. Yet the shopkeeper is poorer by the cost of replacing something he already had, while other sellers lose a possible customer. The repair restores the window; it does not add a window’s worth of new wealth to the community.
This distinction matters because spending and prosperity are not the same thing. A payment can generate income for the person who receives it, but counting that income alone leaves out the resources spent and the alternatives displaced. Repair work can be necessary and worthwhile; preventing damage simply avoids having to spend resources to return to the starting point.
A shattered pane makes the repair visible. The coat that was never bought—and the work its production might have supported—remains unseen, which is why the loss is so easy to miss.
