  Given a vast concern about high income inequality in Thailand as opposed to
empirical findings around the world showing people's preference for fair income
inequality over unfair income equality, it is therefore important to examine
whether inequality in income distribution in Thailand over the past three
decades is fair, and what fair inequality in income distribution in Thailand
should be. To quantitatively measure fair income distribution, this study
employs the fairness benchmarks that are derived from the distributions of
athletes' salaries in professional sports which satisfy the concepts of
distributive justice and procedural justice, the no-envy principle of fair
allocation, and the general consensus or the international norm criterion of a
meaningful benchmark. By using the data on quintile income shares and the
income Gini index of Thailand from the National Social and Economic Development
Council, this study finds that, throughout the period from 1988 to 2021, the
Thai income earners in the bottom 20%, the second 20%, and the top 20% receive
income shares more than the fair shares whereas those in the third 20% and the
fourth 20% receive income shares less than the fair shares. Provided that there
are infinite combinations of quintile income shares that can have the same
value of income Gini index but only one of them is regarded as fair, this study
demonstrates the use of fairness benchmarks as a practical guideline for
designing policies with an aim to achieve fair income distribution in Thailand.
Moreover, a comparative analysis is conducted by employing the method for
estimating optimal (fair) income distribution representing feasible income
equality in order to provide an alternative recommendation on what optimal
(fair) income distribution characterizing feasible income equality in Thailand
should be.
