1. Keynes,
Treatise on Money (1930), in Collected Writings, vol. V, pp.
111-14.
2.
R. G. Hawtrey, The Art of Central Banking,
London: Longmans, 1932, pp. 343-44.
3.
Haberler explicitly referred to Hawtrey's
criticism to the Treatise on Money in his own criticism to the
multiplier in "Mr. Keynes' Theory of the `Multiplier': A
Methodological Criticism", Zeitschrift für
Nationalökonomie VII, 1936, pp. 299-305.
4.
Letter
388 , [jump to
page] .
5.
Harrod discussed indeed the matter with
Marschak: see letter
398 , [jump to
page] . There is no indication as to whether Harrod had
exchanges with Opie on the subject.
6.
E. Lindahl, "A Note on the Dynamic Pricing
Problem", later published in O. Steiger, Studien zur Entstehung
der Neuen Wirtschaftslehre in Schweden. Eine Anti-Kritik, Berlin:
Duncker & Humblot, 1971, pp. 204-11 (also in Keynes, Collected
Writings, vol. XXIX, pp. 123-29). The paper was actually sent to
Harrod: his copy of the four-page Ts is in HCN 10/11/1.
On
12 November, Haberler sent to Lindahl part of his correspondence
with Harrod (CcTLS, in GH Box 66). Lindahl interpreted the debate
as follows:
- I think the solution of the
whole dilemma lies in the distinction between the ex ante
concepts and the ex post concepts of saving and investment.
Taken as ex ante concepts, that is as the planned amounts for a
so short period that the plans are realized, there is of course
normally a difference between the saving and the investment, as
they refer to different persons. Calculated ex post, they can
through definition be regarded as equal.
It is
very easy for me to follow your reasoning, if I interpret your
terms as ex ante amounts. I can then also agree with Robertson,
as the ex ante amount of saving for the next period under
certain assumptions can be regarded as equal to the realized
saving for the foregoing period (if the individuals expect the
conditions to continue). [...]
In the
same way I can follow Harrod and other economists who hold the
opposite view, if I interpret the concepts as ex post amounts.
I will not deny that other definitions ex post are possible
that do not lead to equality between the terms. But I think it
is most natural to take the position that they may be equal. If
the total income is defined as the whole net produce during the
period, calculated ex post, then that part of this produce that
is taken over by the consumers can be defined as consumption
and the other part, containing the net increase of capital,
that is taken over by the investors, even if it should be
unvoluntary (f. ex. unsold stocks), can be regarded as
investment.
So much
as regards the terminological aspect of the question. Regarding
the underlying differences as to methods, I am more on your
side, in so far as I think the ex ante concepts have greater
importance than the ex post concepts, when one has to explain
the causal development. (Lindahl to Haberler, 20 November 1934,
TLS, in GH Box 66).
7.
In Lindahl's symbolism,
stands for ex-post investment, defined as the increase of capital
employed by the firm, calculated at the end of the period.
is ex-post total saving. 
is the sum of all net incomes, also calculated at the end of the
period in question. 
is the expected depreciation of the capital stock, occasioned by
the delivery of products during the period, minus the appreciation
of the same stock that is expected to take place; the term is
based on the estimations of the entrepreneurs at the end of the
period. The subscripts a, b, ... n indicate the different stages
of the productive process: the stage a contains the production of
services and non-durable goods which are sold to the consumers,
the stage b the production of capital goods which are sold to the
producers in stage a, and so on.
8.
"If savings and investment both are calculated
at the end of the period, they are thus identical" (Lindahl,
"Dynamic Pricing Problem", in Studien zur Entstehung ..., p. 208,
or in Keynes's Collected Writings, vol. XXIX, p. 127).
9.
Lindahl, "Dynamic Pricing Problem", in Studien
zur Entstehung ..., p. 204, or in Keynes's Collected Writings,
vol. XXIX, p. 124.
10.
D. H. Robertson, "Saving and Hoarding"
(1933).
- a. TLS
with autograph corrections, two pages on two leaves, in
HP
IV-395-422. Cc in NKP
NK/3/5/15-16.
b.
Harrod's address was written at the
bottom of the first page.
c.
TS, carbon copy, two pages on two
leaves; in HP IV-395-422. Further Cc, together with the
copies of the Harrod-Haberler correspondence, in NKP
NK/3/5/17-18.
d.
Ts: «but exclude».
e.
Ts: «put equal».
f.
The sentence in brackets was added as an
afterthought, and was typed directly on the leaf Harrod
received.
g.
The last two sentences are directly
typed on the leaf Harrod received.
h.
Lindahl's address was written at the
bottom of the first page.
. [8] My first objection was
this: If anybody saves and the sum which he saves
disappears somewhere (say in the banking
system), no investment corresponds to this act of saving (unless this
deficit is compensated from some other source; but you
exclude [d] this possibility
by assumption.) I asked myself how it is in this case possible, from
the ex post standpoint, that savings are equal to investments. In
order to find out, I turned to equation system (2), from which the
equality of 
and 
is derived and, I believe, I was able to detect the point of
confusion. On the right hand side of your first equation you have:
, that is income spent on consumers' goods. This income is taken over
from the preceding period. Part of it is spent on consumers' goods.
The other part (
) is saved. The second column of your equation system is: 
, which you sum up to 
. This is the income realised or earned during the given period.
These two incomes you put as
[e] equal and therefore they cancel out and 
becomes equal to 
.
(or, if you like, a part of the first 
) is hoarded, the second 
becomes smaller than the first. This possibility is so important that
a theory which excludes it (especially a theory which calls itself
dynamic) deprives itself of much of its value.