That's the new book by Jacob Hacker and Paul Pierson. I have a different take on the main argument, but this is an important book for raising some of the key questions of our time. I would recommend that people read it and give it serious thought. The writing style is also clear and accessible. Two of the key arguments are:
1. Skill-based technological change is overrated as a cause of growing income inequality among the top earners.
2. "The guilty party is American politics."
You'll find an article-length version of some of the Hacker-Pierson argument here, although the book covers much more.
I agree with #1, so let me explain why my take on #2 differs:
1. Median income starts stagnating in 1973 and income inequality starts exploding in 1984, according to the authors. However, I consider this a "long" time gap for the question under consideration, namely whether there is a direct causal relation and whether people at the top are using politics to skim from people further below in the income distribution. Furthermore income growth stagnates around 1973 for many countries, not just the United States, and most of those countries never experienced the subsequent "inequality boom" of the Anglosphere. If they avoided the later inequality, why didn't they also avoid the stagnation? The discussion of the causal issues here isn't convincing and the authors' hypothesis is not compared to alternatives or tested against possible disconfirming evidence.
2. There is a lot of talk of unions, but I could concede various points and that's still just a ten to fifteen percent one-time wage premium, when workers are unionized. It won't much explain persistent changes in growth rates over time, whether for the top one percent or the slow income growth at the median. Furthermore the main U.S. sectors are harder to usefully unionize than, say, Canada's mineral and resource wealth or Europe's manufacturing.
3. The authors underestimate the role of finance in driving the growth in income inequality. Their p.46 shows a graph suggesting that non-financial professionals are 40.8% of the top 0.1 percent. Maybe so, but the key question is what percentage of income those professionals account for. The Kaplan and Rauh paper, not cited in this book, suggests a central role for finance. In 2007 the top 5 hedge fund earners pulled in more income than all the CEOs of the S&P 500 put together. On top of that, some "non-financial" incomes are driven by financial market trading, such as in energy or commodity companies. And a lot of top-earning lawyers are doing financial deals, etc.
Turn to Table 7 of the paper cited by the authors, p.56 here. The "non-financial" category still looks bigger but it's incomes in the finance category which grow most rapidly and Bakija and Heim suggest that stock options and asset price movements account for a big share of the growth in "non-financial" incomes. My view is that the increasing liquidity of financial markets drove much of the trend, which was distributed across both the "non-financial" and the "financial" sector. If liquid financial markets allow a privately-owned warehouse company to buy a trucking company on the cheap, and profit greatly (plus the managers pull in a lot), I am calling that a financial markets development, even though it's in the "non-financial" sector.
4. Let's say the story at the top is mostly one of finance. You could describe that as: "some change in financial markets led to rapid income growth for the top earners and politics did nothing about that." Fair enough. But it's still a big leap from that claim to portraying politics as the active force behind the change. Politics was only the allowing force and I don't think there was much of a conspiracy, even if various wealthy figures did push for deregulation or more importantly an absence of new regulation. I also don't think anybody was expecting incomes at the top to rise at the rates they did; it was a kind of pleasant surprise for the top earners to be so lucratively rewarded. So the major change is left unexplained, for the most part, and the whole story is then shifted onto the passive actor, namely the public sector, which is elevated to a major causal role which it does not deserve.
5. pp.47-51 the authors talk about tax rates. If we had kept earlier high marginal rates, the top earners would not have received nearly so much and also they would not have worked so hard. Maybe so, yet this won't much explain the stagnating pre-tax incomes at the median and it doesn't fit very well into the overall story, unless you wish to make a complicated "lower tax revenue, lower quality public services, MP of the median earner goes down" sort of story.
6. If the top earners are screwing over their wage earners in the big companies, by pulling in excess wages, options, and perks, we should observe non-stagnant median pay for people who avoid working in firms with fat cat CEOs. Or we should observe talented lower-tier workers fleeing the big corporations, to keep their wages up. Yet no evidence for these predictions is given, nor are the predictions considered. It is likely that the predictions are false.
7. To the extent the high incomes at the top come through capital markets, it is either value created or a transfer/redistribution. You can argue over the percentages, but to the extent it is the former it is not at the expense of the median. To the extent it is the latter, the losers will be other investors, not the median earner or household, who does not hold much in the way of stock (lower pension fund returns don't count in the measure of median stagnation).
8. What follows p.72 is an engaging, readable progressive history of recent American politics, but the economic foundations of the underlying story have not been pinned down.
9. In my view, most likely we have two largely separate phenomena: a) median wage growth slows in 1973 because technology stagnates in some regards, and b) liquid financial markets, in various detailed ways, allow people with resources to earn a lot more than before. Politics may well play a role in each development, but with respect to b) its role has been largely passively, rather than architectural and driving.
Anyway, I found it a very useful book for organizing my thoughts on these topics.
Addendum: Matt Yglesias comments.