What it argues
Scarcity is Sendhil Mullainathan and Eldar Shafir's argument that the experience of having too little — of any resource — produces a predictable cognitive syndrome with consequences that extend far beyond the original deficit. A person short on money thinks about money constantly; a person short on time thinks about deadlines. This focused attention is partly adaptive (scarcity tunnels you toward what matters most) and partly destructive (it crowds out everything else). Mullainathan and Shafir call the cognitive cost of scarcity a tax on mental bandwidth.
The bandwidth concept is the book's most original contribution. Drawing on psychology and behavioral economics experiments, the authors show that poverty, time pressure, and loneliness all reduce cognitive capacity in measurable ways — affecting fluid intelligence test scores, self-control, and decision quality. The Indian sugarcane farmers who were tested before and after their annual harvest scored significantly higher on cognitive tests after receiving their income than before, not because they were different people but because the cognitive load of financial scarcity was removed. The poor are not making poor decisions because they lack intelligence or values; they are making decisions under conditions that would impair anyone's thinking.
What it gets right
- 1.
Scarcity — of money, time, food, or social connection — captures attention and focuses cognition on the scarce resource. This is partly useful (focus) and partly costly (tunnel vision).
- 2.
Scarcity imposes a cognitive bandwidth tax. People experiencing scarcity perform measurably worse on fluid intelligence and self-control tasks than when the same scarcity is removed.
- 3.
The tunneling effect of scarcity means important things outside the tunnel get neglected. Time-scarce people miss medical appointments; money-scarce people miss bill payments — not because they don't care but because they're not in the tunnel.
What it covers
Who wrote it
Sendhil Mullainathan is a behavioral economist and professor at the University of Chicago Booth School of Business, formerly at Harvard. He was awarded a MacArthur Fellowship in 2002. Eldar Shafir is a psychologist and professor of public affairs and psychology at Princeton University. The two researchers met at MIT and collaborated on scarcity research for over a decade before writing this book. Mullainathan has also worked extensively on applying behavioral economics to development economics in low-income countries.
