Baumol’s law says that labor-intensive services with slow productivity growth tend to become relatively more expensive over time because wages rise with the rest of the economy even when output per worker does not.
The core mechanism
Suppose productivity in manufacturing rises quickly but productivity in live performance, education, or parts of health care rises slowly. Workers in the slow-productivity sector still need wages competitive with the rest of the labor market.
If wages rise economy-wide but output per worker in the service sector changes little, unit cost rises:
$$ \text{Unit cost} = \frac{\text{Wage}}{\text{Productivity}} $$
That is the logic behind “cost disease.”
Why economists care
Baumol’s law helps explain why some public and personal services absorb a larger share of spending over time even without obvious waste. Rising cost shares can be a structural result of differential productivity growth, not just bad management.
Policy context
The concept matters for:
- public budgeting for health and education,
- inflation measurement in service-heavy economies,
- comparisons between goods-producing and service-producing sectors.
It does not mean every cost increase is justified. Institutions, technology, and incentives still matter. The point is that even an efficient service sector can become relatively more expensive if its productivity grows slowly.