闪电传记——闻人羽的直播资料

在当今的信息时代，闻人羽带来了一场视觉与听觉上的新体验。他是个富有想象力且不可招责于任何选择的直播大卫，被广大粉俁和忠实粉俁都热爱。闪电传记是他所在的直播频道——一个全球范围内唤醒了人们对音乐和生活兴趣的火焰，成为现代年轻一代不仅是对音乐的爱好者，也是对真实人物折射社交元素的深入了解者。

闪电传记频道以其独特的内容和生态系统开创新方式。通过直播和互动，他不只是提� Written on 02 May, 2019 by Paul Krugman

The big economic news story over the last few weeks is of course Brexit. But there’s another big story – a potentially longer-lasting one that might have important implications for the world economy and even U.S. politics. It involves two American economists, Brad DeLong and Paul Krugman (that's me), who have taken to Twitter to exchange arguments about whether or not the Federal Reserve should be raising interest rates.

The argument comes down to this: is a trade-off between inflation and employment still worth worrying about? Or has technology driven the economy so far along that there are no longer any slack in the labor market, with full employment being essentially permanent? In short – should we continue to think of macroeconomic policy as trying to fine-tune output around a stable trend (as traditional economic models have it) or as attempting to control inflation and keep unemployment near its natural rate (as new-Keynesian theory has it)?

In one sense, this may not sound like very big deal. But the differences here go much deeper than you might think. And they are relevant in today's economy – a world where we have seen more than 2% inflation over the last few years and unemployment rates of less than 4%.

Let me start with Brad DeLong’s view, which is pretty clear on Twitter: he argues that we need to keep raising interest rates. Here's his reasoning as laid out in a tweet from April 28th (and here’s an earlier post summarizing it). First off – let’s acknowledge the reality of inflation-targeting central banks, who have been struggling against persistent and uncomfortably high inflation for most of this decade. For example:

So I believe we should continue to raise rates in order to slow down an economy that is running too hot… The reason I do not care about the NAIRU or the natural rate hypothesis is because they are irrelevant, since we no longer have a stable trend toward full employment. We don't know how fast the Phillips Curve will shift with each technological revolution...

Now here’s what DeLong says that he sees as supporting this view:

A large body of econometric research [by David Autor and others] has shown that US labor markets have changed in ways consistent with a flat or negative Phillips curve relationship. The "non-accelerating inflation rate of unemployment" (NAIRU) is either shrinking at an ever faster pace, or not existent…

So DeLong's view amounts to this: we need to continue raising interest rates because it’s the only way that central banks can slow down economic growth. The economy doesn’t have enough slack – unemployment isn’t high enough -- and monetary policy is still effective in controlling inflation.

My response, as laid out on April 29th:

@BradDeLong @PaulKrugman I think your argument has two major problems... Firstly, the Phillips curve relationship appears to be changing over time but not necessarily becoming negative or flat. Secondly, monetary policy is already very expansionary, so raising rates wouldn't help with inflation anyway…

In a subsequent tweet that same day (and here’s an earlier post of mine on this point), I elaborated:

If you look at the data over time – for example since 1950 -- then it looks like unemployment and inflation have both been falling over the last several decades, with no sign yet that we've reached a trough. That suggests that the Phillips curve may be changing but not necessarily becoming negative or flat. And there are lots of reasons why monetary policy can help with inflation control:

I then asked for DeLong’s thoughts on my response – and they were forthcoming (here):

@PaulKrugman So, you're suggesting the Phillips Curve is a function of expectations? In that case the "curve" may be positive if expected inflation rises. But I don't believe this is true: AER 2018 by David Autor, et al. suggests no sign of any flattening over time -- nor do data since WWII point in such a direction (see my comments on your post).

My response to DeLong’s reply – and I have now published it on this blog:

I've spent some time looking at the papers you mention, including Autor et al.'s 2018 paper. The argument of that paper is basically this: US labor markets are evolving in a way that makes them less sensitive to changes in unemployment rates – which means the Phillips Curve relationship may be changing over time (though not necessarily becoming negative). However, I don’t think we can conclude from their results that inflation won't matter any more if employment gets too high. As a result, I still believe monetary policy could help with inflation control even though the economy isn’t running "too hot".

In other words: DeLong and I are basically in agreement on one thing – namely, that changes over time may be taking place in US labor markets which will make them less sensitive to employment shocks. But there is disagreement about what that means for macro policy. And it’s important to remember this point: even if the Phillips Curve relationship has become flatter or negative (as some people believe), it doesn't mean we don’t have slack in labor markets, and therefore monetary policy isn’t effective at controlling inflation anymore – as DeLong seems to think.

In a subsequent tweet on April 30th, I added more evidence for the view that we still need tighter macroeconomic policies: “@BradDeLong @PaulKrugman The NAIRU data in this chart are not conclusive but they suggest inflation pressures could be rising. If true then it might support a case for raising interest rates."

And here’s my latest thinking on the subject, as laid out in an op-ed I wrote in yesterday's New York Times: “The Phillips Curve Is Not Dead.” It points to some key evidence that while labor markets may not be tightening, inflation is showing signs of picking up – and this gives policymakers reason for concern.

So why has all the discussion about monetary policy taken place on Twitter? Well, as Krugman pointed out in an earlier post:

The key issue here isn't whether we should or shouldn't raise interest rates. The real question is where those rates ought to be - and that's a judgment call which depends on how you think about the economy now... To me it looks like the answer is "somewhere between 1% (more) and 3%".

I agree with Krugman there: this isn’t really an argument over whether or not interest rates should go up – but rather a debate over where they need to be. And I think we have reason for optimism in the short term that inflation will remain under control. But given how long it's taken policymakers time and again to bring down inflation when it has got out of hand, and with some evidence emerging recently suggesting a possible pick-up in price pressures, I’m not confident enough at this juncture to say that there is no reason for central banks to act.

To sum up: the discussion between DeLong and myself is going on right now (and beyond) precisely because we've been so focused on trying to tame inflation over the last 40 years, and in particular since 2016. But a lot has changed recently – as I wrote yesterday -- which may well mean that this time our past successes at fighting inflation are no longer appropriate for today’s economic environment.

The question we should be asking is not whether or not interest rates should go up, but rather how high they need to go in order to get the economy back on a stable footing and avoid another bout of soaring inflation. And as I wrote yesterday, my sense right now is that monetary policy could stand being tightened somewhat, even if it doesn't look like we have much slack left in US labor markets – simply because there are reasons to worry about inflation picking up a bit faster than policymakers expect.

Of course, as DeLong points out today (see this tweet), the real question isn’t whether or not interest rates should go up, but rather how high they need to go in order to get the economy back on a stable footing and avoid another bout of soaring inflation... @PaulKrugman

The fact that we're debating monetary policy at all is telling – because it tells us that central bankers are worried about getting macroeconomic policies right in today’s world. It also shows how difficult the task ahead will be, particularly if inflation does pick up a bit over the next few months – and policymakers need to react accordingly (and quickly).

In case it wasn't clear before: I still think monetary policy can help with inflation control even though labor markets may not be running "too hot". But we shouldn’t pretend that things have gone back to the way they were 40 years ago. We are in a very different world today – and policymakers need to acknowledge this fact when considering how much monetary policy needs to change if inflation does rise unexpectedly over the next few months.

I should add that, while I'm not arguing for more stimulus now or going back to zero interest rates, it also isn’t a good time right now to tighten too quickly – particularly given how much slack remains in labor markets and if there are downside risks around the corner (as Krugman says).

And here's some related thinking on this issue by Mark Thoma.