373. D. H. Robertson to Harrod , 6 October 1934 [a]

[Replies to two letters not found; follows on from 372 , continues at 380 ]

Trinity [College, Cambridge]

6 October 1934

My dear Roy,

Many thanks for the riposte [1] & 2 more letters. It seems to me perfect in tone & temper, & I have no amendment to suggest. 1 If you have any in mine, please let me know before we send in the proofs. [3]

I think you idealise the state of the other sciences! Surely physics above all is in much the same state as we are, i.e. different people trying to build workable pictures--which don't always fit in together--because the real world is too complicated to be studied directly. (Of course there are differences, because of the greater facility of experiment in natural sciences, etc.).

But I admit I'm surprised at the size of the gap which evidently yawns between us. It appears to me that your new scheme resembles Maynard's Treatise one (now, I gather, abandoned) in that, setting out to be an analysis of causes, it ends by being a repetition of results. [4] You are really both of you (& this applies to what I have been able to gather about his more recent work as well) dealing with a succession of static positions, and not, as you set out to be, with the process of change. [5] That is a very crude, and perhaps erroneous, way of putting what I take to be the cause of the gap: at any rate, I feel sure that there is a gap, & that it is best therefore it should be brought to light.



  1. 1. Harrod, "Rejoinder to Mr. Robertson" ( 1934:11 ).

    2. The sentence to which Robertson refers runs as follows: "And on certain quite reasonable assumptions curious and untoward repercussions may occur, even if a stable money policy is maintained" (Harrod, "Rejoinder to Mr. Robertson", p. 478).

    3. Robertson, "Mr. Harrod and the Expansion of Credit" (1934).

    4. This criticism to Keynes's Treatise on Money (1930) was raised by R. G. Hawtrey, The Art of Central Banking, London: Longmans, 1932, pp. 343-4.

    5. Harrod maintained that Robertson was illicitly assuming "that the period prior to that considered was one of complete stationariness", and that the difference between this problem and that of regular advance

    • is analogous to the difference between the dynamics of getting a train to move and the dynamics of a train in motion at a constant velocity. I was concerned to investigate the latter problem, and for that purpose it is proper to take a cross-sectional view, assuming that the immediately preceding and succeeding periods yield similar developments, and to find out what assumption with regard to the increase and mutual relations of the factors concerned are self-consistent with normal economic motives ("Rejoinder to Mr. Robertson", 1934:11 , p. 478).

    (For similar considerations also see letter 368 to Haberler of 8 September 1934, [jump to page] .) The matter was probably discussed also in one of the missing letters to Robertson, and may have been added to the Economica Rejoinder only after Harrod received this comment from Robertson: this conclusion is suggested by Robertson's footnote, indicating that the words "being missed" were located in last line but five, while in the printed version the corresponding word "maintained" precedes the passage quoted here (line 15 from the bottom).

    1. a. ALI, two pages on a halved sheet, in HP IV-990-1069d/22.

1. (Except "being maintained" for "maintaining" in last line but 5.) [2] [Robertson's note].

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