The underlying assumptions of rational economic decision making:
consumers aim to maximise utility
firms aim to maximise profits
Governments aim to maximise social welfare
Consumers aim to maximise utility: Utility is the satisfaction gained from consuming a product
Firms aim to maximise profit: Economic theory assumes that firms are run for their owners and shareholders and so aim to maximise profit in order to keep the shareholders happy.
Governments aim to maximise social welfare : Governments are voted in by the public and work for the public, so should aim to maximise their satisfaction by taking decisions which increase social welfare