The Basics
- Simple definition: As more of one input is added while others are held fixed, the additional output from each extra unit eventually decreases.
- Core idea: There’s only so much you can get from adding more workers to a fixed factory.
- Think of it as: Too many cooks eventually spoil the broth – each additional cook adds less, then nothing, then negative.
What It Actually Means
The law of diminishing marginal returns applies in the short run when at least one factor is fixed. Adding variable inputs (labor, fertilizer) initially may increase output at an increasing rate, then at a decreasing rate; eventually, total output may fall. It’s not about quality declining – it’s about fixed factors limiting the effectiveness of additional variable inputs.
Example
A Pakistani textile factory with fixed machines adds workers. First workers: output rises fast. More workers: still rises but slower as machines become crowded. Eventually, adding workers may reduce output (too many, getting in each other’s way). This is diminishing returns.
Why It Matters
Diminishing returns explains why countries can’t grow forever by just adding labor or capital – technology must improve. It underlies cost curves (rising marginal cost) and informs optimal input decisions.
Don’t Confuse With
Diseconomies of Scale – diminishing returns is short-run with fixed factors; diseconomies of scale is long-run with all factors variable.
See also
Production Function • Marginal Product • Returns to Scale • Short Run • Law of Variable Proportions
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