(i) Samuelson states that the means are scarce so such means could be put to alternative uses.
(ii) He makes his definition dynamic by including the element of time.
(iii) His definition is applicable only in a barter economy, where money is not used.
(iv) Samuelson treats economics as a social science, whereas Robbins regards science of individual behaviour.

Micro Economics:
(i) Understand the operation of an economy.
(ii) It provides tools for economic policies.
(iii) It examine the condition of economic welfare.
(iv) Efficient utilization of resources.
(v) Useful in international trade.
(vi) Useful in decision making
(1) Optimal resources allocation
(2) Basis for prediction.
(3) Price determination

a. Samuelson's Definition (Modern Definition of Economics)
Samuelson's definition is known as a modern definition of economics. According to samuelsons, "Economics is a social science concerned chiefly with the way society chooses to employ its resources which have alternative uses, to produce goods and services for present and future consumption"
b. Common Points:
The above definition is general in nature there are many common points in the definitions of Robbins and samuelson. Samuelson's definition tells us that economics is a social science and it is mainly concerned with the way how society employs its limited resources for alternative uses.
All this we find in the definition of Robbins. But Samuelson goes a step further and discusses how a society uses limited resources for producing goods and services for present and future consumption of various people or groups An interesting point that Samuelson tells is that the society may or may not make use of money.

1. Economics does not treat wealth as be all and end all of economic activities.
2. Man promotes primarily welfare and not wealth.
3. Man is the centre of his study. According to him the study of man is more important than the study of wealth.
4. The science of Economics contains the concerns of ordinary people who are moved by love and not to get maximum benefit.
5. Economics is a social science. It studies people in the society who influence one another.