The Social Welfare Function (SWF) is a decision rule to rank alternative social states in a complete fashion in terms of social welfare. This paper questions the philosophy of Paretian Principle as a desirable property of the SWF. It shows that it is possible to generalize the widely used Sen SWF, which can be non-Paretian under special circumstances. Also, it demonstrates the disaggregation method of this SWF by components of income using the Gini decomposition process. The method is applied to Australian Household Expenditure Survey data to estimate the trend of welfare of total income and its components in Australia from 1984 to 1993-1994.