[p.v]
PREFACE
This book is chiefly addressed to my fellow economists. I hope that it will
be intelligible to others. But its main purpose is to deal with difficult
questions of theory, and only in the second place with the applications of this
theory to practice. For if orthodox economics is at fault, the error is to be
found not in the superstructure, which has been erected with great care for
logical consistency, but in a lack of clearness and of generality in the pre
misses. Thus I cannot achieve my object of persuading economists to re-examine
critically certain of their basic assumptions except by a highly abstract
argument and also by much controversy. I wish there could have been less of the
latter. But I have thought it important, not only to explain my own point of
view, but also to show in what respects it departs from the prevailing theory.
Those, who are strongly wedded to what I shall call 'the classical theory', will
fluctuate, I expect, between a belief that I am quite wrong and a belief that I
am saying nothing new. It is for others to determine if either of these or the
third alternative is right. My controversial passages are aimed at providing
some material for an answer; and I must ask forgiveness If, in the pursuit of
sharp distinctions, my controversy is itself too keen. I myself held with
conviction for many years the theories which I now [p.vi] attack, and I
am not, I think, ignorant of their strong points.
The matters at issue are of an importance which cannot be exaggerated. But,
if my explanations are right, it is my fellow economists, not the general
public, whom I must first convince. At this stage of the argument the general
public, though welcome at the debate, are only eavesdroppers at an attempt by an
economist to bring to an issue the deep divergences of opinion between fellow
economists which have for the time being almost destroyed the practical
influence of economic theory, and will, until they are resolved, continue to do
so.
The relation between this book and my Treatise on Money, which I
published five years ago, is probably clearer to myself than it will be to
others; and what in my own mind is a natural evolution in a line of thought
which I have been pursuing for several years, may sometimes strike the reader as
a confusing change of view. This difficulty is not made less by certain changes
in terminology which I have felt compelled to make. These changes of language I
have pointed out in the course of the following pages; but the general
relationship between the two books can be expressed briefly as follows. When I
began to write my Treatise on Money I was still moving along the
traditional lines of regarding the influence of money as something so to speak
separate from the general theory of supply and demand. When I finished it, I had
made some progress towards pushing monetary theory back to becoming a theory of
output as a whole. But my lack of emancipation from preconceived ideas showed
itself in what now seems to me to be the outstanding fault of the theoretical
parts of that work (namely, Books III [p.vii] and IV), that I failed to
deal thoroughly with the effects of changes in the level of output. My
so-called "fundamental equations" were an instantaneous picture taken
on the assumption of a given output. They attempted to show how, assuming the
given output, forces could develop which involved a profit-disequilibrium, and
thus required a change in the level of output. But the dynamic development, as
distinct from the instantaneous picture, was left incomplete and extremely
confused. This book, on the other hand, has evolved into what is primarily a
study of the forces which determine changes in the scale of output and
employment as a whole; and, whilst it is found that money enters into the
economic scheme in an essential and peculiar manner, technical monetary detail
falls into the background. A monetary economy, we shall find, is essentially one
in which changing views about the future are capable of influencing the quantity
of employment and not merely its direction. But our method of analysing the
economic behaviour of the present under the influence of changing ideas about
the future is one which depends on the interaction of supply and demand, and is
in this way linked up with our fundamental theory of value. We are thus led to a
more general theory, which includes the classical theory with which we are
familiar, as a special case.
The writer of a book such as this, treading along unfamiliar paths, is
extremely dependent on criticism and conversation if he is to avoid an undue
proportion of mistakes. It is astonishing what foolish things one can
temporarily believe if one thinks too long alone, particularly in economics
(along with the other moral sciences), where it is often impossible to bring
one's ideas to a conclusive test either formal or [p.viii] experimental.
In this book, even more perhaps than in writing my Treatise on Money, I
have depended on the constant advice and constructive criticism of Mr. R. F. Kahn.
There is a great deal in this book which would not have taken the shape it has
except at his suggestion. I have also had much help from Mrs. Joan Robinson,
Mr. R.G. Hawtrey and Mr. R.F. Harrod,
who have read the whole of the proof-sheets. The index has been compiled by Mr.
D. M. Bensusan-Butt of King's College, Cambridge.
The composition of this book has been for the author a long struggle of
escape, and so must the reading of it be for most readers if the author's
assault upon them is to be successful,¾a struggle of
escape from habitual modes of thought and expression. The ideas which are here
expressed so laboriously are extremely simple and should be obvious. The
difficulty lies, not in the new ideas, but in escaping from the old ones, which
ramify, for those brought up as most of us have been, into every corner of our
minds.
J. M. KEYNES
December 13, 1935
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