The modern economist Lionel Robbins has highly criticized Marshall’s definition of economics. He gave the most scientific and logical definition of economics in his book (An essay on the nature and significance of economic science) in 1932 A.D. According to him, “Economics is the science which studies human behavior as a relationship between ends and scares means which have alternative uses”. His argument is that economics is concerned with the problems arising from scarcity. People solve the problem of scarcity by allocating scarce resources to the best possible use. Most of the man’s economic activities are moving around the problem of scarcity and choice. This is the central idea in Robbins’s definition. The main points or ideas in Robbins’s definition are as follows:

1. Unlimited human wants or use.
   According to Robbins’s, human wants are unlimited. These unlimited wants are not possible to satisfy at a time. If one want is satisfied, another arises in our mind immediately. Thus there is a chain of wants, one want chasing another. There are no ends of human needs.
2. Limited resources.
   Human wants are unlimited but the means to satisfy them are limited relatively. The wants are more times than means. We called such a resource as a limited whose supply is less than demand. Limited resources mean time, money, wealth, etc.
3. Scarce resources have an alternative use.
   Human wants are unlimited but the means to satisfy this wants are scare but the scare means have alternative uses. For example, money can be used to buy food, a book or to go to the cinema.
4. All wants are not equally urgent.
   According to Robbins’s, all wants are not equally urgent. They differ in urgency. Some wants are more urgent than the other ones. So, more urgent wants need more immediate satisfaction and others can wait. Current wants are more important than future wants. For example  – Medicine is more important than cosmetics for a sick girl.
5. Problems of choice
   Although human wants are unlimited, all the wants are not equally important or urgent. More important wants have to be fulfilled immediately and less important wants have to be fulfilled immediately and less important can be postponed. So, human beings make a choice of wants to derive maximum satisfaction. So, according to Robbins’s, choice making is really an economic problem.

Criticism of Robbin’s Definition of Economics
The definition of economics given by Robbins is analytical, logical and scientific. Robbins’s definition is regarded as a superior definition to the rest of all definition of economics because he has provided newness in his definition. But several economists like Fraser, Samuelson, Wotton, etc have strongly criticized in the following points.

1. Hidden concept of welfare.
   Robbins has criticized the concept of Marshall but critics claimed that his definition itself includes the concept of welfare through the back door. Robbins’s definition of economics is concerned with the choice between wants and allocation of resources for maximum satisfaction. In fact, maximum satisfaction is a sign of welfare.
2. The economic problem arises not only from society.
   According to Robbins’s definition, an economic problem arises due to the scarcity of resources. But the problems like inflation, unemployment, etc. arise due to the abundance of resources. The problem of unemployment is due to the abundance of manpower. So, it is not correct that economic problem arises due to scarcity only.
3. Confusion between means and end.
   Robin believes that means and end are easily separable. But in practice, it is difficult to distinguish between means and end for example:- an M.A. student aims to get M.A. degree. This is an end for him. Once he gets it, he uses it as a means to get employment. Thus the same thing may be means in one situation and the end in another.
4. Wider scope than need.
   Robbins’s definition includes the study of all human activities related to alternative uses in economics. Since all of the activities of human life are included, its scope is being varied vastly. It makes difficult to draw the line of demarcation of economics.
5. It ignores the theory of economic growth.
   The theory of economic growth has recently become a very important branch of economics but Robbins’s definition does not cover it. Economics of growth explains how an economy grows by increasing the national income and productive capacity of the economy. But Robbins takes the resources as given and discusses only there allocation.

Although, it was unable to address hot issues of the present-day economy such as unemployment, inequality, economic growth, national income, etc. Robbins’s definition is more scientific, logical, and universally acceptable than other definition of economics.