When a Price Increase Changes the Budget
For most goods, a higher price encourages people to buy less: shoppers switch to alternatives or simply go without. A Giffen good is a rare exception. Its price rises, yet a very poor household ends up buying more of it because the price increase makes the household poorer in practical terms.
The key is that the good must be an inferior staple: people turn to it more when they have less money, often because it is a cheap source of calories. It must also take up a large share of a tight budget, while better foods remain costly.
How the Paradox Works
Imagine a family that buys potatoes for most of its calories and meat when it can afford it. If potatoes become more expensive, the family’s food budget loses purchasing power. Meat may now be out of reach. The family cuts back on meat and relies more heavily on potatoes—even though each potato costs more.
Two forces are pulling in opposite directions. The higher price gives the family a reason to substitute away from potatoes. But the loss of buying power pushes it toward the staple it depends on. A Giffen effect occurs only when that second force is stronger, so the family buys more of the staple overall.
Why It Is an Exception
Being cheap or inferior is not enough. If a household has accessible substitutes, or if the staple consumes only a small part of its budget, the usual response—buying less when the price rises—will generally prevail. Giffen behavior is most plausible where poverty, dependence on one basic food, and limited alternatives combine.
That is why the potato-and-meat example captures the mechanism: a price shock can reshape the whole food budget, not just the choice between two items. The paradox is not that people prefer an expensive staple; it is that the price rise leaves them too poor to afford the foods they would otherwise choose.
