Which outcome is the full Jevons paradox?

Efficiency improves but total resource use rises because use expands enough. Exactly. The paradox requires an increase in total use, not merely reduced savings.

What is missing from a per-task energy estimate?

How the number of tasks changes. Exactly. Total consumption depends on scale as well as resource use per task.

What did Jevons challenge in 1865?

The inference from economical fuel use to reduced economy-wide consumption. Exactly. He questioned the aggregate conclusion, not the reality of technical improvement.

From the archive · October 21, 2026

When using less makes us use more

Can a more efficient machine increase total resource consumption?

01 · Word

Jevons Paradox

Pronounced JEV-unz PAIR-uh-doks

noun

The possibility that greater efficiency increases total resource use by making the resource's services cheaper and more widely used

Examples

Jevons paradox would occur if cheaper computation expanded use enough to raise total energy demand.
A small rebound that reduces savings without reversing them is not the full Jevons paradox.

Origin

The name refers to economist William Stanley Jevons and his 1865 book The Coal Question. He challenged the inference that economical use of coal in a process necessarily meant lower coal consumption across the economy.

02 · Idea

Multiply efficiency by how often it gets used

Suppose a machine requires half as much energy per task. If the number of tasks stays fixed, energy use falls. If cheaper tasks encourage three times as much activity, total use rises instead. The machine is more efficient in both cases. Total energy use depends on how much it runs.

Economists call an offset to expected savings a rebound effect. The stronger case, in which the offset exceeds the savings, is often called backfire or Jevons paradox. A partial rebound reduces the savings; backfire reverses them.

Less per use does not settle the number of uses.

Measure the total after demand responds.

Limits

Backfire is a possibility, not a law attached to every efficiency improvement. Prices, saturation, regulation, and other constraints affect the response.

03 · Moment

An economist questions coal economy

Britain, 1865; Jevons publishes The Coal Question

Jevons examined improvements that made coal-powered production more economical. He argued that cheaper power could extend industrial activity and open additional uses, increasing the demand for coal. A better engine could therefore intensify dependence on the resource its individual operation conserved.

Author: William Stanley Jevons
Resource: Coal
Argument: Economy of fuel versus total use

The caveat

The size of any rebound depends on the technology and its users. Jevons' argument alone cannot tell us whether a modern efficiency gain will increase consumption.

Jevons considered the wider economy: cheaper engines could make more factories and uses of coal profitable.

The connection

Efficiency can lower the cost of a service enough to expand demand beyond the savings per use.