The new book by Thomas Piketty, that is. Hunter Lewis and Peter Klein tell us what you need to know. What they note is similar to my initial thoughts upon hearing of the new book which is being trumpeted as the latest in a long trail of discarded hopes called "game changers" and "must reads" that will "change the way we think about economics forever." Let us please stop with the hyperbole.
It turns out that government intervention, especially in the form of monetary inflation is the primary cause of income inquality in more developed countries. When the Fed decides to inflate, the new government-initiated, bank-created money is given to some people--often Wall Street investors--while the rest of us must pay higher prices.
For additional insight, I recommend this brand new video by Mark Thornton on The Mises View: