Scarcity

Scarcity refers to the basic economic problem, the gap between limited – that is, scarce – resources and theoretically limitless wants. This situation requires people to make decisions about how to allocate resources efficiently, in order to satisfy basic needs and as many additional wants as possible. Any resource that has a non-zero cost to consume is scarce to some degree, but what matters in practice is relative scarcity. Scarcity is also referred to as "paucity."

In his 1932 Essay on the Nature and Significance of Economic Science, British economist Lionel Robbins defined the discipline in terms of scarcity:

Economics is the science which studies human behaviour as a relationship between ends and scarce means which have alternative uses.

In a hypothetical world in which every resource—water, hand soap, expert translations of Hittite inscriptions, enriched uranium, organic bok choy, time—was abundant, economists would have nothing to study. There would be no need to make decisions about how to allocate resources, and no tradeoffs to explore and quantify. In the real world, on the other hand, everything costs something; in other words, every resource is to some degree scarce. 

Money and time are quintessentially scarce resources. Most people have too little of one, the other, or both. An unemployed person may have an abundance of time, but find it hard to pay rent. A hotshot executive, on the other hand, may be financially capable of retiring on a whim, yet be forced to eat ten minute lunches and sleep four hours a night. A third category has little time or money. People with abundant money and abundant time are seldom observed in the wild. 

Even resources considered infinitely abundant, and which are free in dollar terms, are scarce in some sense. Take air, for example. From an individual's perspective, breathing is completely free. Yet there are a number of costs associated with the activity. It requires breathable air, which has become increasingly difficult to take for granted since the industrial revolution. In a number of cities today, poor air quality has been associated with high rates of disease and death. In order to avoid these costly affairs and assure that citizens can breathe safely, governments must invest in methods of power generation that do not create harmful emissions. These may be more expensive than dirtier methods, but even if they are not, they require massive capital expenditures. These costs fall on the citizens in one way or another. Breathing freely, in other words, is not free.

If a government decides to allocate resources to making the air clean enough to breathe, a number of questions arise. What methods exist to improve air quality? Which are the most effective in the short term, medium term and long term? What about cost effectiveness? What should the balance between th? What tradeoffs come with various courses of action? Where should the money come from? Should the government raise taxes, and if so, on what and for whom? Will the government borrow? Will it print money? How will the government keep track of its costs, debts and the benefits that accrue from the project (ie, accounting)? Pretty soon, the scarcity of clean air (the fact that clean air has a non-zero cost) brings up a vast array of questions about how to efficiently allocate resources. Scarcity is the basic problem that gives rise to economics.