If a rational consumer must consume either zero or one unit of a good, then an increase in the price of that good with no change in income or in other prices can never lead to an increase in the consumer's demand for it.

Rational Consumer

An economic concept of a consumer who seeks to maximize utility or satisfaction from goods and services within the constraint of their budget.

Price Increase

A rise in the cost of goods or services, which can be due to various factors such as inflation, increased production costs, or higher demand.