Talented people usually earn more, especially when their talents are “marketable”, highly valuable and in demand among large groups of consumers or users. Hence, it’s tempting to conclude that income inequality is the natural and necessary result of the given inequality in the distribution of marketable talents. However, that conclusion only holds up when you turn things around: rather than talented people earning more, it has to be true that people who earn more generally have more and better talents, talents moreover which are in demand. I don’t know of any study confirming this claim, but my anecdotal observations in the matter tell me that the claim isn’t true: many rich people don’t have special talents, and many talented people aren’t rich at all.
But then why are some people rich? Perhaps they have some other native endowments, such as a strong will, discipline and a natural willingness to make an effort. Or perhaps they have successfully acquired these characteristics during the course of their upbringing and education. Income inequality is then the product of the natural and/or acquired inequality of effort. But, again, it’s easy to find wealthy people who are neither talented nor strong willed, and many poor people work very hard. As someone has said: hard work is much more common than success.
Maybe luck plays a large part in the creation of wealth: some people have the good fortune of acquiring – perhaps through inheritance – certain means of production. Others are born in a place and family that provides good education, numerous wealth creating opportunities, encouragement etc. Still others find themselves in an economy where demand for their particular contributions is high, or where these contributions are highly valued. Or maybe they find themselves in a political system where discrimination and certain government policies give them an advantage.
Your personal thoughts on the relative importance of talent, effort or luck will determine what you think should be done about income inequality. Those who believe effort is the main cause tend to assume nothing should be done. If wealth distribution is the sole result of differences in effort, then redistribution is not only unfair to those who invest more effort, but also has perverse consequences: it will destroy all future wealth and therefore make all future redistribution impossible, because punishing people for their efforts means taking away their incentives to invest effort.
If you think talent or a native endowment of discipline is the main cause of wealth inequality, then you will probably be more sympathetic to redistribution. Since no one deserves his or her talents or other native endowments, no one deserves the unequal rewards that come with unequal endowments. However, since people still need to use and develop their endowments, you’re likely to reserve at least a small role for effort. Hence, you’re not likely to be a strict egalitarian. Still, you will favor education as a means to foster some people’s lingering talents and underdeveloped sense of discipline, and perhaps you’ll also favor a more equal distribution of the attention society gives to different talents.
If you think income inequality is mainly caused by luck or the lack of it, you will be a strong egalitarian. You view talent and effort, as well as the ability and willingness to use and develop talents and to invest effort, as the products of good fortune: you’re lucky to have the right genes, parents and teachers who encourage you etc. And you also view other types of good fortune as causes of wealth: being in the right place at the right time, inheriting means of production, meeting the right business partners etc. Luck is undeserved, and so are its products. Hence redistribution is morally required.