Someone told me recently that they had less free time after adopting a productivity system I helped them set up. Each task was cheaper, so more tasks had become worth doing. They were busier because the system worked.

Economics has a familiar account of this.

The two effects

When oranges halve in price, you buy more oranges relative to apples. This is the substitution effect: demand moves towards the thing whose relative price fell.

You also spend less on the original basket, leaving you effectively richer and able to keep the savings. This is the income effect. Substitution pushes towards more consumption; income creates room to relax.

The maths

Treat tasks and leisure as two goods bought from one time budget.

Tasks completedLeisure timeBefore toolAfter toolABCU₁U₂lostleisure

From A to B, cheaper tasks pull you along the same satisfaction curve towards more work and less leisure. This substitution effect always occurs. From B to C, the time saving makes you richer and returns some leisure through the income effect.

The move from A to C therefore always contains more tasks, while the change in leisure depends on which force dominates. For productivity tools, the Jevons observation is that substitution usually wins: C contains more tasks and less leisure than A.

The Slutsky equation states the decomposition formally:

∂x/∂p = (∂x/∂p)|U - x · (∂x/∂m)

The first term is substitution, which always pushes towards the cheaper good. The second is income, whose direction depends on whether the good is “normal”. Both terms produce more tasks; for leisure they oppose, and leisure falls whenever substitution is stronger. The person who told me they were busier had simply moved to C.

Applied to productivity tools

Before the system, capturing a process, documenting a decision or following up a thread carried 20 to 30 minutes of friction. Most tasks stayed below the threshold of being worth the bother. Afterwards, the same tasks took three to five minutes, roughly an order-of-magnitude reduction.

That price change pulls neglected tasks above the threshold. You capture what would have gone uncaptured, follow threads you would have dropped and document decisions that would have stayed in your head. The new demand consumes the freed time, so you do more work rather than the same work faster.

Jevons paradox

In 1865, William Stanley Jevons observed that James Watt’s steam engine made coal use more efficient while coal consumption increased. Efficiency made new uses economical, so total demand rose.

The same mechanism appears elsewhere:

  • Roads: Widen a highway and traffic increases. Induced demand. Trips that weren’t worth the congestion become viable.
  • Storage: Give people more disk space and they fill it. Files that weren’t worth keeping become worth keeping.
  • Communication: Make messaging free and the volume explodes. Conversations that weren’t worth a phone call become worth a quick text.

Making knowledge work cheaper produces more knowledge work in the same way.

The backlog was already infinite

There was never a finite amount of work followed by freedom. The possible backlog of things to capture, document, systematise, follow up and improve is effectively infinite.

High friction used to hide most of it. Only urgent or valuable tasks crossed the threshold; the rest existed but were not worth considering. The tool makes that backlog visible.

Claiming the income effect

A tool cannot hand you free time; you have to claim it by leaving viable tasks undone when the time is worth more elsewhere. Lowering the cost of a task does not lower the value of your time. Some newly cheap tasks deserve to cross the threshold, while many still do not.

The discipline lies in refusing work that has become possible without becoming worthwhile. That is the difference between being productive and merely busy.