Sartorial fashion is cyclical. Every few years, certain trends that had dropped out of style become hot on the catwalk again – meaning that ideas are constantly recycled.

服装时尚是有周期性的。每过几年，某些本已不再流行的潮流会在T型台上再度红火。这意味着创意在周而复始地循环。

Something similar may be under way in central banking too. Five decades ago, central bankers assumed that it was sometimes sensible to use targeted regulatory controls to create a healthy economy and financial system.

这一规律或许也存在于央行工作领域。50年前，央行官员们认定，使用针对性监管控制，以保障经济与金融体系的健康，有时是合理的。

But then, from the 1980s, it became fashionable to presume that macroeconomic management sat in a different silo from financial regulation: the former was dominated by debates about inflation targets and interest rates; the latter focused on bank supervision.

但接着，从20世纪80年代开始，宏观经济管理与金融监管分属不同范畴的观点流行起来：前者主要是辩论通胀目标和利率；后者专注于银行监管。

Now the pendulum is swinging again. This week, Mark Carney, governor of the Bank of England, warned that the rapid pace of UK house price rises could threaten the British recovery, prompting speculation that the BoE will begin to tighten policy before long.

现在“钟摆”又在向另一个方向摆动了。不久前，英国央行(BoE)行长马克•卡尼(Mark Carney)警告称，英国房价上涨速度之快可能威胁经济复苏，令人猜测该行将在不久后开始收紧政策。

But if so, it is unlikely to rely exclusively on the tools it has used in the past decade – namely its power to set interest rates or to influence the rate at which money is created. Instead, the bank’s Financial Policy Committee might well turn to so-called macroprudential measures, which are intended to prevent financial excess. For example, it could impose loan-to-value caps for mortgage lending, or require banks to hold bigger capital buffers against certain types of loan.

但如果是这样，英国央行不太可能仅仅依赖它在过去10年里使用的工具，即设定利率或影响货币创造速度的权力。相反，该行的金融政策委员会(FPC)很可能转向所谓的宏观审慎措施，防止发生金融业过分行为。例如，央行可能设定针对抵押贷款的贷款与估值比率(loan-to-value ratio)上限，或者要求银行针对某些类型的贷款持有更高的资本缓冲。

Such regulatory meddling fell out of favour in the late 20th century. But since the 2008 financial crisis policy makers have discovered what they once knew but seemed to have forgotten: that macroeconomics cannot be divorced from finance and that it is sometimes difficult to steer the economy through interest rates alone.

这种监管“插手”在20世纪后期失宠了。但自2008年金融危机以来，政策制定者发现了自己曾经掌握但似乎已忘记的知识：宏观经济不可能与金融脱离；有时仅靠利率难以引导经济。

Thus, when emerging market countries such as South Korea introduced measures to prevent excessive “hot money” investment inflows a couple of years ago, they labelled these “macroprudential” measures, where previously they might have called them “capital controls”.

于是，韩国等新兴市场国家几年前出台抑制过多投资“热钱”流入的措施时，为其贴上了“宏观审慎”措施的标签，而以往它们可能称其为“资本管制”。

Then, last year, countries such as New Zealand, Norway and Switzerland borrowed the label, too, to describe moves they were taking to combat domestic credit bubbles. Now big western countries are catching the wave and linking financial regulation to macroeconomic management: aside from the BoE, the European Central Bank is promoting macroprudential measures, too, and the idea is being debated at the US Federal Reserve.

接着，新西兰、挪威和瑞士等国也把这一标签贴在抑制国内信贷泡沫的措施上。如今，西方大国也赶上了这一潮流，正在将金融监管和宏观经济管理联系起来。除英国央行之外，欧洲央行(ECB)也在推崇宏观审慎措施，而美联储(Fed)在辩论这一主张。

What should investors make of this? One obvious lesson is that progress in policy making tends to follow the pattern of a Hegelian dialectic; ideas that seem terribly old-fashioned to one generation have a habit of being reborn with subtly fresh twists.

投资者应当如何解读这一潮流？一条显而易见的经验是，政策制定的演变往往符合“黑格尔辩证法”：在一代人看来相当过时的思想，经常会带着一丝新意重焕生机。

Another lesson is that these paradigm shifts do not always start with economists – or big central banks.

另一条经验是，这些范式转变并非总是始于经济学家或者大国的央行。

Think, for example, about how the last great shift occurred in relation to inflation targeting. Back in the late 1980s, the central banks of New Zealand and Sweden started experimenting with this out of frustration with the shortcomings of the previous central bank paradigm of targeting money supply. It was only later that the concept spread to countries such as the UK, at which point academic economists created an intellectual framework to justify this new mantra.

比如，想一想上一次朝着通胀目标制的重大转变是如何发生的。早在20世纪80年代后期，由于对之前央行紧盯货币供应量的操作范式的缺点感到沮丧，新西兰与瑞典两国央行启动了通胀目标制实验。只是到了后来，这一概念才扩展到英国等国家，学术界的经济学家为新范式构建了一套理论框架。

As Paul Tucker, former deputy governor of the BoE, recently observed, this pattern is playing out again: ideas that started in places such as New Zealand are spreading, and academics are scrambling to catch up. For what is striking about the new macroprudential fashion is that there is still relatively little intellectual scaffolding surrounding it, although groups such as the International Monetary Fund are now trying to put one together.

正如英国央行前副行长保罗•塔克(Paul Tucker)最近所评述的，这一幕正再度出现：源于新西兰等地的观念在扩大影响，学者们争先恐后地赶上这股潮流。因为新的宏观审慎时尚的引人注目之处在于，其周围尚未搭好“理论脚手架”，尽管国际货币基金组织(IMF)等组织正在进行这方面的努力。

A third point to note is that central banks (and economists) would do well to be a little humble about their ideas. It is clear that policies such as inflation targeting, money targeting or macroprudential management can all be useful. But they all have potential shortcomings. Setting policy purely to target consumer price inflation does not work well if the biggest danger is an asset price bubble; but meddling in financial markets is not always as effective as raising interest rates to curb bubbles either. What limited evidence there is suggests that earlier experiments with macroprudential policy have produced mixed results

第三点值得注意的是，央行（和经济学家）对于自己的观点最好还是谦逊一些。显然，通胀目标制、货币目标制或宏观审慎管理等政策，可能都是有用的。但它们都有潜在的缺点。倘若最大的危险是资产价格泡沫，制定仅仅盯住消费价格指数的政策，效果不会太好；但是，就抑制泡沫而言，干预金融市场也未必总像加息一样有效。有限的证据似乎表明，先前的宏观审慎政策实验取得了好坏参半的效果。

The one thing that is clear is that, whenever there is blind faith in any single paradigm, that paradigm will eventually fail. The fact that the BoE and others are relearning that finance and macroeconomics need to be analysed together is welcome, if long overdue.

能够确定的一点是，无论什么时候，只要对哪个单一范式产生盲目信任，那个范式最终都会失败。英国央行与其他央行重新领悟到金融与宏观经济需要一起分析，这一点令人欣慰，即便它们早该这么做了。

But do not expect this new macroprudential paradigm to be a magic wand. Just remember the history of inflation targeting; or think of flares.

但不要指望宏观审慎这一新范式成为一根魔棒。只要回忆一下通胀目标制的历史，或想一想喇叭裤的际遇，就会明白。