Sounds and Fury

到底政策是不是造成今日美國社會不平等的重要原因之一？這個問題在政治學者看來似乎是無庸置疑，沒想到經濟學者不這麼認為。不過看完這個辯論到最後，我也同意政治/政策因素的效果必須被「證明」，而不是只是宣稱。

第一個辯論是關於到底財政部長還是克魯曼先生是對的。名校Dartmouth大學經濟系教授Andrew Samwick說，克魯曼自己就是那收入最高的百分之一，他難道笨到看不出來自己這是因為他自己的教育和她的個人能力嗎？難道他的收入是因為他所討厭的共和黨所造成的嗎？

這個問題有點愚蠢。他後面的問題顯然答案是肯定的。亦即個人能力和政策都與她的收入有關。即使克魯曼是出自個人能力獲得今日的高收入，但賦稅政策的確可以讓他維持這些所得。更不要說，用一個人的例子來分析社會趨勢，實在沒有意義。

另一個經濟學者Mark Thomas就說了，

 it's the system that has changed. And what I'm talking about is the system, not whether individuals have earned their places in it. Why is that so hard to understand?

但Andrew Samwick一直要追問，

But what is the mechanism for ideology driving outcomes in the top 1 percent?..

可是，克魯曼不是指出了幾個機制嗎？不論是稅制或是工會角色。 我想，問題不是在於機制，而是如何用經驗證據去證明這些政策，而不是其他因素的確造成了長期不平等的趨勢。

名教科書作者Greg Mankiw也跳進來表示支持Samwick，說

Policy choices such as tax rates and minimum wages have not been the main causes of increasing inequality. At least that is the consensus, as I understand it, of the professional labor economists who study the issue...

但對於這個所謂共識的宣稱，Delong反對，並提供相關研究。

..................

在這點上，第二場辯論就比較有意義：到底賦稅政策是對哪方面不平等產生影響。

 Brad Delong

The problem that I have with Paul Krugman's argument here is that the shifts in income inequality seem to me to be too big to be associated with anything the government does or did. Yes, Roosevelt and company were pushing in the right direction. Yes, Reagan, Gingrich, Bush, and company have been pushing in the wrong direction. But what they did and do affects (I think) after-tax income inequality much more than the before-tax income inequality numbers, and the before-tax numbers show the trends remarkably strongly. And I can't see the mechanism by which changes in government policies bring about such huge swings in pre-tax income distribution.

但有人反對。 Matthew Yglesias:

Paul Krugman writes that politics matters for the income distribution, citing the long-term trends in inequality and their close correlation with long-term political trends. Brad DeLong says he thinks this is wrong, political changes can and do have a large impact on after-tax income distribution but the trends show up strongly in pre-tax income. "I can't see the mechanism by which changes in government policies bring about such huge swings in pre-tax income distribution." I note for the edification of readers that one thing I've learned since arriving in DC is that a difference of opinion on this subject is a major divide within the progressive economic policy community. Most mainstream economists -- including most liberals -- agree with DeLong. Politics and policy affect the secondary distribution (after tax and transfer) and what happens with the primary distribution is just out there. Leftier economists tend to say this is mistaken. I would side with Krugman on this. The trend data is too striking to be ignored. If you have a phenomenon and are having trouble identifying the cause, the thing to do is to try harder to identify the cause, not assert that the phenomenon isn't happening. But what is the cause? I can think of some plausible stories. One thing to say is that tax policy impacts pre-tax distribution. When the top income tax rate was very high -- 70 percent or above -- this not only meant that rich people paid a lot in taxes, it also meant that there were a broad range of circumstances where it didn't necessarily make much sense to offer well-compensated people even more compensation. When you have a very progressive rate structure, an employer can get a lot more bang for his buck by directing his employment budget at middle-income people than at rich people. As you flatten the tax structure, this becomes less-and-less the case. Similarly, very high tax rates encourage high income people to engage in more leisure and less work whereas right now we have the somewhat odd situation where highly compensated people tend to work more than do the moderately compensated. All this, I think, makes a big difference. Then the other factor to note is probably unionization which is much more impacted by policy decisions than people often seem to realize.

 但Brad Delong還是有謹慎的懷疑

Falling value of the minimum wage. Shift in the personnel at the National Labor Relations Board and the role of that shift in the decline of unions. Loosening up on the regime that regulates Wall Street and the consequent shift from the Berle-Means technostructure corporation to the modern takeover game, plus institutional corruption via IPOs and compensation subcommittees of boards of directors. Declining marginal tax rates on the rich making it less unreasonable for your CEO to demand compensation in cash rather than in a fancy executive dining room. Trade. Immigration--which has a powerful effect on the American income distribution even if it does little to shift the income distribution among the native born. How much bang can these politically-driven changes have? And how much is the politics the result rather than the cause of rising inequality?

【在另外地方，他對上面這些因素作了評估：

My sense (and it is just a guess) is that declining unionization and union power might account for perhaps a fifth of the widening in income inequality; that reductions in the value of the minimum wage might account for a tenth; and that legal changes that have shifted the balance of power within the corporation toward CEOs might account for another tenth. I have a hard time finding other policy changes that have a big impact--and only a portion of declining unionization and union power is due to changes in government policy since the 1970s.】

所以他自己的結論是

I'm skeptical--I think it's more likely than not that politics are a reinforcing factor rather than the driving force--the moving crest of the tsunami and the froth on top of that rather than the originating earthquake, which I would see as probably in society and technology--but it's an open question, and now I have another reason to eagerly look forward to Paul Krugman's next book.

 ps.上述辯論請見Delong的整理

針對這些的辯論，克魯曼寫了email給Brad Delong，說明他對各個因素與不平等關係的看法。

Paul Krugman emails:

I think it's really important to realize that we have only a modest amount of direct evidence that technological change is driving increased income inequality. That is, while there have been a few studies showing some connection between increased use of IT and changes in the wage structure, very little of the conventional wisdom that technology is the culpritis based on those studies.

So why is technology given the credit? Basically because it's the residual category - and as Bob Solow said about the role of technology in growth, the residual is the measure of our ignorance. We estimate the effects ofthe stuff whose effects we know how to measure - taxes and globalization, mainly - and then attribute the rest to technology.

The point is that it's all too possible that we're attributing to technology rising inequality that may be largely due to hard-to-quantify political and institutional change.

There are several reasons to think that politics plays a big role. One is the broad correlation between the political climate and trends in inequality, which I pointed out in the Times.

Another piece of evidence is the wide difference in inequality trends between the US and to a lesser extent the UK, on one side, and everyone else.

Yet another piece of evidence, which I think is very suggestive, is the discontinuous nature of the Great Compression. If you go back to the original Goldin and Margo paper, http://www.nber.org/papers/W3817, they found that there was a drastic reduction in wage inequality over the course of just 5 or 6 years in the 40s, which then stuck for another 30 years. In the paper, they struggle to reconcile this with a supply-and-demand framework, but it sure looks like a change in norms which had sustained effects on market outcomes.

So what are the mechanisms? Unions are probably top of the list; I believe that there's a qualitative difference between wage bargaining in an economy with 11 percent of workers unionized, which is what we had in the early 30s, and one with 35 percent unionization, which is what emerged from World War II. That's discontinuous change, partly driven by a change in political regime. And the process went in reverse under Reagan.

An overall climate of public scrutiny may matter too, especially at the top of the scale.

And don't forget that some taxes affect the pre-personal-tax distribution of income. Taxes on corporate profits went from a minor inconvenience before FDR, to a major source of revenue under Eisenhower, and back again.

The bottom line is that the view that rising inequality reflect forces beyond the reach of politicians may sound sensible, but it's actually a supposition based on very little evidence, and there's a lot of evidence on the other side.