储蓄与投资不是两回事——读《经济解释》（八十）
首先看作者描述的凯恩斯及其学派对储蓄与投资的看法：
凯恩斯及其学派把储蓄与投资看作两回事：前者是漏失或漏出（leakage），使消费减弱因而导致不景及失业；后者是注入（injection），因而增加经济活力。
作者眼中的正面典型，费雪呢？前文已经描述过，这里再次做了一下参照：
收入消费后余下来的是储蓄，今天不消费改做明天才消费是投资。换言之，费雪的储蓄是今天看收入不消费余下来的，投资是今天余下来的用作明天的消费。二者是同一回事，只是时间的角度不同。因为投资一定要让时间走一程，利息于是出现。利息一方面是投资的回报，另一方面是提前消费之价。
这里不是为了“正名”，只是看看，凯恩斯到底是怎么看投资和储蓄的？翻翻他的《通论》第六章：
Whilst, therefore, the amount of saving is an outcome of the collective behaviour of individual consumers and the amount of investment of the collective behaviour of individual entrepreneurs, these two amounts are necessarily equal, since each of them is equal to the excessof income over consumption. Moreover, this conclusion in no way depends on any subtleties or peculiarities in the definition of income given above. Provided it is agreed that income is equal to the value of current output, that current investment is equal to the value of that part of current output which is not consumed, and that saving is equal to the excess of income over consumption—all of which is conformable both to common sense and to the traditional usage of the great majority of economists—the equality of saving and investment necessarily follows.
In short—
Income = value of output = consumption + investment.
Saving = income − consumption.
Therefore saving = investment.
所以，与费雪的定义是一致的。
那么，凯恩斯是否有过将储蓄与投资区分开来？继续看《通论》第七章中的阐述：
We come next to the divergences between saving and investment which are due to a special definition of income and hence of the excess of income over consumption. My own use of terms in my Treatise on Money is an example of this.....
Thus the new argument, though (as I now think) much more accurate and instructive, is essentially a development of the old. Expressed in the language of my Treatise on Money, it would run: the expectation of an increased excess of investment over saving, given the former volume of employment and output, will induce entrepreneurs to increase the volume of employment and output. The significance of both my present and my former arguments lies in their attempt to show that the volume of employment is determined by the estimates of effective demand made by the entrepreneurs, an expected increase of investment relatively to saving as defined in my Treatise on Money being a criterion of an increase in effective demand. But the exposition in my Treatise on Money is, of course, very confusing and incomplete in the light of the further developments here set forth.
答案揭晓，张五常说到的漏出与注入，确实有过：
- 在《货币论》中曾经这样区分过；但是
- 这来自于对收入的不同定义；而且
- 凯恩斯自己说，非常让人迷惑（confusing）而且不完整（incomplete）。
所以，还是以《通论》为准。关于定义的解读，这样算是比较明确了。
那么，为什么凯恩斯曾经做这种两分呢？其实《通论》第七章中也给出了答案，还是上面那一段中：
The significance of both my present and my former arguments lies in their attempt to show that the volume of employment is determined by the estimates of effective demand made by the entrepreneurs, an expected increase of investment relatively to saving as defined in my Treatise on Money being a criterion of an increase in effective demand.....
张五常的解读和这个是一致的：
我认为凯恩斯及其学派把储蓄与投资作为两回事看，主要因为不同的投资对就业与物品产出往往有着很不相同的效果。购买土地是投资（也是储蓄），但如果购入土地的人不动土，只是持着土地等将来，对就业半点贡献也没有。很多投资（储蓄）事项对就业与产出的贡献不大，这些贡献的大、小分歧项项不同，可以有很大的变化，说之不尽。
这里还是要提一下凯恩斯经济学的年代：
- 是大萧条，是就业问题之严重甚至都带来了希特勒的上台，以及后续的二战；
- 这也因此，《通论》的英文全名是 The General Theory of Employment, Interest and Money —— 就业是第一位的；
- 所以，看凯恩斯及其经济学，必须考虑时代背景，及对于就业，这一核心问题的，最核心关注。
那么，大萧条时期，会发生什么呢？继续看《通论》第十六章：
The mere act of saving by one individual, being two-sided as we have shown above, forces some other individual to transfer to him some article of wealth old or new. Every act of saving involves a ‘forced’ inevitable transfer of wealth to him who saves, though he in his turn may suffer from the saving of others. These transfers of wealth do not require the creation of new wealth—indeed, as we have seen, they may be actively inimical to it. The creation of new wealth wholly depends on the prospective yield of the new wealth reaching the standard set by the current rate of interest. The prospective yield of the marginal new investment is not increased by the fact that someone wishes to increase his wealth, since the prospective yield of the marginal new investment depends on the expectation of a demand for a specific article at a specific date.
张五常的解读和这个是一致的：
引起混淆的关键似乎是：当经济不景，或前景不明朗，或有战乱的恐惧，很多人会避去投资于产出或增加就业的项目。他们会偏向于转向不事产出物品的投资，因而减少工人就业的机会。
自卫的行为可能被凯恩斯学派视作储蓄的意图增加，投资的意图减少。
这看法不对，因为只是改变了投资（储蓄）的性质。
这里就可以看出来，混淆来自于“投资”这个名词的定义：
- 有时候说的是整体宏观上的“储蓄 = 投资”的投资
- 有时候说的是微观层面，企业及个人的创造新财富的“投资”
- 而后者才一定会创造财富、因此也创造就业，而不只是转移财富。
再看看上文《通论》的那句话：
Every act of saving involves a ‘forced’ inevitable transfer of wealth to him who saves, though he in his turn may suffer from the saving of others.These transfers of wealth do not require the creation of new wealth....
投资于不创造财富的物产，这种行为，背后的动因是什么？
我们还是先看看凯恩斯如何描述，《通论》第十七章：
The owners of wealth will then weigh the lack of ‘liquidity’ of different capital equipments in the above sense as a medium in which to hold wealth against the best available actuarial estimate of their prospective yields after allowing for risk. The liquidity-premium, it will be observed, is partly similar to the risk-premium, but partly different;—the difference corresponding to the difference between the best estimates we can make of probabilities and the confidence with which we make them...
There is, clearly, no absolute standard of ‘liquidity’ but merely a scale of liquidity—a varying premium of which account has to be taken, in addition to the yield of use and the carrying-costs, in estimating the comparative attractions of holding different forms of wealth. The conception of what contributes to ‘liquidity’ is a partly vague one, changing from time to time and depending on social practices and institutions. The order of preference in the minds of owners of wealth in which at any given time they express their feelings about liquidity is, however, definite and is all we require for our analysis of the behaviour of the economic system.
所以，凯恩斯将其归结于“流动性溢价”这一分析视角。但是，流动性的背后是什么呢？张五常怎么看？
另一方面，说“自卫”的行为会导致消费下降却没有错。从交易费用的角度看，前景不对头时较多的投资者会采取自卫行为，因而增加失业的看法是不大正确的。
其实更多的是不大“精确” —— 对于现象的描述是准确的，没有找到根本原因，不够“第一性”：
正确的看法，是因为交易费用的存在，投资于物品产出不容易脱身而拿回自己的投资。转向较为容易脱身回本的项目，对就业与国民收入皆不利。
回归到了交易费用的这个概念，这其实也就是支撑“流动性溢价”的一个视角，能去分析“流动性溢价”的来源及其转变 —— 而这其实也已经呼应了凯恩斯的分析，还是上面那一段：
The conception of what contributes to ‘liquidity’ is a partly vague one, changing from time to time and depending on social practices and institutions.
至此，这一小节的核心内容应该说是分析完了；而关于收藏品的两个例子就不在这里描述了，可以放到第四章中一起来看。
PS：读《通论》最好还是对照英文原版来看，中文版各个版本质量我不晓得，但至少我看的那个版本中翻译错误带来的误解，还是让人不太愉快的。
