UNDERSTANDING BUSINESS Robert E. Lucas, Jr. University CYCLES* of Chicago I. Why repeated Keynes’ the is it General main in capitalist about Theory, outstanding this challenge business that, fluctuations trend, the resolution challenges cycle theorists, there the stand the problem Keynes, aggregate theory of the consequence of the Keynesian away from this question of this was a rapid increase economic theories at a point underinter- which has Lausanne Revolution was the redirection onto the apparently in time, taking Revolution, due in the level of precision were with general by the economics.2 consequence the interwar remains quantities, expressed of output to meet among Theory;’ primarily of theoretical effort and attempts into theory, Cycle we here perfectly of the determination secondary theory’ been A primary phenomena Trade of all economic most as one of as to what it would mean to contradiction, of modern Prior to was regarded Moreover, equilibrium dependence School of research of cyclical of economic By ‘equilibrium undergo as a leading example: they are in ‘apparent crucial variables the same character? research, theory. was wide agreement [T] he incorporation which cycle To cite Hayek, the system aggregate of this question to economic were called business solve this problem. economies, all of essentially formulated. more simpler history to Tinbergen and explicitness As a result, question as given.3 than A to with which Keynesian macro- * Paper prepared for the Kiel Conference on Growth without Inflation, June 22-23,1976;revised, August 1976. I would like to thank Gary Becker, Jacob Frenkel, Don Patinkin, Thomas Sargent, and Jose Scheinkman for their comments and suggestions. 1 Hayek (1933), p. 3311. ‘Hayek (1933), p. 42~ 3 Thtsredirection was conscious and explicit on Keynes’ part. See, for example, the first sentence of his chapter on the trade cycle. “Since we claim to have shown in the preceding chapters what determines the volume of employment at any time, it follows, if we are right, that our theory must be capable of explaining the phenomena of the trade cycle ” (1936), p. 313. economics has benefited from several decades of methodological improvement whereas, from this technical point of view, the efforts of the business cycle theorists appear hopelessly outdated. Yet from another that point of view, they seem quite modern. macroeconomics commonplace, is in need and need and about economists though there what it would would problem have as roughly of a microeconomic is much no difficulty equivalent a coherent and useful aggregate from further statement attempts macroeconomics there one’s is a more immediate a theoretically sound contribution once which sources the toward and not Keynesian discussion of the could from effect hoped could The process and legislative to explain immediate, an undesirable scientific or very state, had been the hope or their influence envisaged that, mitigated was the painfully on the other side, there improvement. cycles accompanied short-term, however of the the public cycles” with institutional business current and which business reform; for interest in the nature of instability, be removed but search of the work of pre- of to offer to “explain or “permanent” effort aim in itself, the contemporary redirection sources changes. of long-term abandonment policy theorists, to which was a sharp change The effort institutional hope economy cycle structures as a resumption the economists institutional these slow one of public that of will result from the acceptance is a worthwhile economics Revolution to accept. understood, the theory for interpreting Accompanying at identifying by appropriate was statement or not this is so, I wish by the business ancestors aggregative to policy largely directed Hayek’s Whether the jerry-built reason by the Keynesian has come economic intellectual theorists. occasioned of this it, it is likely that many modern has led us. Honoring Keynesian own. has become the nature be so, or that the most rapid progress as advanced to refine about accepting to their in this essay to argue that it should of the problem confusion mean to satisfy The observation foundation The a belief movement arrived of the at, to a better state. The to come belief closer economics is so are only symmetric. If manipulation diverts entirely the from argument much erosion the cycle discussion such postponement understandable is attainable, to to make life more improve business on which that attempt to objective it is the only legitimate widespread trying attention be effective; this latter a willful “destructive,” who that to achieving and that the attempt task of research in aggregate the contrary difficult lot of mankind. theorists were of aggregative is, moreover, in the belief 8 Yet correct, economics of stabilization policies accompanied is viewed as for one’s colleagues the situation the is now which is short-term focused might by the steady on the part of noneconomists only actually and that aggrrgative economics has anything In the next section, the events these and we call business cycles, facts, to the progress finally apparent. to the Hayek and other limits of the phenomena and then turn to the Keynesian made along the line Keynes severe The remainder for cyclical useful to say. I will review some of the main qualitative to this theory, cycle theorists have of to and Tinbergen which essay will consider by an economic business progress features response have initiated, now the prospects become of accounting in the narrow sense in which that term. LI& II. Let me begin to sharpen the discussion by reviewing the main qualitative features of economic time series which we call “the business cycle.” movements about trend in gross national product in any country described by a stochastically These movements which is to say, they sometimes do not arise in the natural The principal broadly defined exhibit high conformity; amplitude prices of aggregates (iv) time of producer goods are and profits show series procyclical; measures long-term which are observed (i) Output movements terminology, language, they durables they have exhibits high tnuch of nondurables. (iii) Production resources lower than average and much greater high series. (v) Prices generally and velocity which (In Mitchell’s and consumer natural or amplitude, wave motions time series. fol1owing.4 move together. of very low order. period regularities aggregative are the in modern Business than other rates Those than does the production agricultural conformity. interest sectors (ii) Production greater sciences. these equation of either the deterministic among different among across coherence.) difference uniformity do not resemble are in the co-movements amplitude disturbed exhibit Technically, can be well rates have conformity are procyclical. slightly so. and (vi) Short-term (vii) Monetary are procyclical. 4 The features of economic time series listed here are, curiously, both “well known” and expensive to document in any careful and comprehensive way. A useful, substantively oriented introduction is given by Mitchell (1951), who summarizes mainly interwar, U.S. experience. The basic technical reference for these methods is Bums and Mitchell (1946). U.S. monetary experience is best displayed in Friedman and Schwartz (1963). An invaluable source for earlier British series is Gayer, Rostow, and Schwartz (1953), esp. Vol. II. The phenomena documented in these sowces are, of cowse, much more widely observed. Most can be inferred, though with some difficulty, from the estimated structure of modem econometric models. An important recent contribution is Sargent and Sims (1976), which summarizes postwar U.S. quarterly series in several suggestiveways, leading to a qualitative picture very close to that provided by Mitchell, but within an explicit stochastic framework, so that their results are replicatable and criticizable at a level at which Mitchell s are not. 9 There is, as far as I know, restricting them regularities common absolutely conclude series, that, a unified governing market to the qualitative economies, omitted rather countries the the U.S., trade For 1 think, beg the origins of cyclical ment, market economies experiencing, attempts exhibit the general laws character- statistics the above bccausc, high from for a large economy enough crucial a phenomenon purely suggests that which requires of a conformity export question to be movements explanations of the ultimate to pass over without com- series in the twenty-five years descriptive Nevertheless, there is nothing level, it is impossible so long a period inherent and account in the pre-World for regular in any way to a presumption cyclical to of relative in the workings living with the level of instability or to which we were subject of capitalist this the possibility or institutional to be sure, and in amplitude War Il. At this to document connected trade country, good luck from good policy. strongly in among economists, movements. but too striking stability of co-movements but to focus on open-economy reduction World is to grounded in part difficult is the general following feature cycles, Also omitted, distinguish there for it suggests of foreign do not more Though by to be is led by the facts inclined than in political a smaller would do much to “explain” appear or periods. behavior statistics interesting. would, behavior cycles, of phenomena-to-be-explained, cyclically observations they economies. it, one and challenging, of business these periods: are all alike. To theoretically to particular I have to anticipate be attractive market catalogue reason explanation istics specific like to all decentralized cycles should to qualify or time with respect business no need countries no theoretical conclusion of to particular of we are now War II years. That is, movements that such movements need not be are an inevitable economies. Ill. The implications the time series features 1937, and which developed early work’ Modigliani, from conform of Keynesian reviewed 1944) this well macroeconomic above. fit well qualitatively; theory and from quantitatively. 5 models Early versions the Tinbergen’s These confomr (for example, models well to by Hicks, econometric models largely independent located the primary For example, see Tinbergen (1939). This work was not explicitly Keynesian; indeed, it was conceived as an empirical complement to Haberler’s review and synthesis of theoretical work on business cycles (1936). Keynes, on his part, was actively hostile toward Tinbergen’s work. See Moggridf: ,‘1~3)~~~. , , 285-320. In referring to those who built in part on Tinbergen’s work as “Keynesian contributing to the continuation of an historical injustice. 10 disturbances to the then in investment highly induce bances volatile general interest was a good movements rates empirical In this accounting theoretical Keynes, from The empirical of the movements This feature The seem very important and historically Tinbergen success generated Goldberger answer, Klein model (1946) to the this criterion) business cycles. a & in the most through economics. of meaning theories emphasis to grounds: did not could distinguish surprise had in an original in their simulation The Adelmans armed between a collection programmed of economic to follow series generated posed, with the methods the Klein- by an actual economy. of the Adelmans (and, in no way directed their one suspects, efforts of to meeting was =.8 This achievement behaves (1959) an observer by a computer who the factors was measured of the U. S. economy. of whether evident in from empirical monetary and Adelman and the analogous and Goldberger, that on role directly all gave great was of these developments artificially equations money (still wage and price no important did not result on discovered apt way by Adelman way, the question procyclical and Modigliani on and prices sector 7 empirically. of Burns and Mitchell series Hicks, distur- with procyclically on, a wage-price play series Since these of rigid wages in money certainly de-emphasis Klein-Goldberger in a precise Later U. S. model) high-amplitude they were consistent The assumption curve) was added to fit observed models; econometricians in these and employment. ” IS shifts,” description, forces. via lags (in Tinbergen’s Movements first approximation. for cycles. monetary linked in output and velocity. later called a Phillips movements. 6 level series. were, in Hicks’ terms, moving The behavior, profit signaled One exhibits literal a new standard understanding sense: a fully articulated time so as to imitate The Keynesian for what it means to understand of business closely macroeconomic explicitness and empirical of the term “theory” cycles artificial by constructing economy the time series behavior models accuracy; could not really be viewed as “theories” were the first to attain by doing to such an extent which of actual so, they altered that the older business this the cycle at all. These models are not, however, “equilibrium theories” in Hayek’s sense. Indeed, Keynes chose to begin the General Theory with the declaration (for ‘Klein and Goldberpr (1955). ‘Tinbergen (1939). pp. 183-185. Tinbergen, as did most subsequent significance of interest rates to test the importance of money. 8 macroeconometricians, used the It ISnot correct that a search for “good tits” would have led to a model satisfying the Adelmans’ criteria; think of fitting polynomials in time to “explain” each series over the sample period. 11 Chapter I1 is no more than this) that an equilibrium that unemployment was not explainable and that the failure of wages to move as predicted be treated as due to forces Keynes verifiable wrote serious whether between sharper fluctuating than at sharply irregular this crucial behind this “cyclical market rates through problem. nominal should an otherwise classical This decision 1 have described, Now in possession economy, means to actual evaluate various proposed as though they had been experimel:tally been attempted conditional requires type hope studied. a property that neither countercyclical with changes structed choose of a model to imitate has almost nothing to answer had certain invariance being course, (1959) forecasts, have differed aCCUI’dte measures. emerged It seemed from this procedure even if such policies Invariance had never codifying of the model under policy can be assured in advance, nor technology vary systematically In contrast, how agents’ with to a new situation. the decision sample period, will be of no use in predicting stable without agents explaining the consequences 12 variations model of the is not, of tastes to with variations rules will in general model Any disequilibrium rules which behavior but it seems reasonable decision An equilibrium agents would ways? This ability in an economic which by to make accurate how in specified tastes policies. over some previous in the way tested of the form: been different of parameters in the environment. to respond actual behavior to do with its ability questions policies of the structure so as to predict by simply quantitatively by to have an inexpensive policy which theory, exploited in any actual economy. Yet the ability the Adelmans appeared tested, of his day freed by equilibrium of detailed, recommendations saw of rigid into a model and fruitfully economic to treat policy it, Keynes postulate theorist imposed economists legitimate labor had avoided time series. was rapidly replicas to supply col!!d be transformed from the discipline macroeconometricians. of the choose cycle theorists it had not resolved for observed this freedom “apparent equilibrium” Why, in the face of moderately on the part of the most prestigious of economists there were is the with the unexplained model were look at a market “economic households time? Most business which did a fair job of accounting and,as behavior. this problem of unemployment for nowhere and was to to illuminate. or not. Nevertheless, choice, choices theory theory one could somehow and those who addressed sidestepping a generation nature phenomena” wages and prices, that by simply prices, as though in labor nominal of economic it is in equilibrium reasons contradiction” the power was unattainable: of individual by the classical the “involuntary” observation, directly empirical theory as though by direct and verify beyond theory as a consequence in change is, by definition, con- and technology will model, have found constructed it useful to use why these rules were used, of nontrivial policy changes. The quantitative importance by examination of specific settled elsewhere’ that it is of fatal importance economic models, these models. graphic primarily Rather illustration: expansionary 4 percent, has averaged were widely the decrease In this the policy deeper curves followed very homogeneity specific the initial response sustained inflation, were equilibrium an equilibrium case apparently variance, monetary flexible of on the and supply and without that, (or “natural”) sustained inflation growth rather than of real output were adopted? fixed has Address. aggregative models. On the equilibrium: the Thus, without to forecast using in any one can, in the case of rate prior to the inflation the same is a relatively not -too simple, as it is still highly one would need a more moments, Phillips which rate will be an is underway. questions, and other of a specific the ability then The issue is Presidential to an inflation, rate, review. models functions. is no inflation. to econometric the standard of economic if the unemployment that unfortunately, not be lost. his in had behavior sustained detailed basis claiming of the economy once the inflation The policy reason from in than characteristic of demand model, clear sector” it was based on apeneral zero-degree detail made (1968) inflation, in macroeconomic proceed “wage-price Phelps was, most of this episode revision did not a better result in question forecasts involved equilibrium of a few new variables as Friedman argument with contrary, the addition it), that of rates than unemploy- lo These by sustained would the lesson this is the only from Friedman’s model, any than (though observation that inflation closely and is now too clear to require that lower themselves (1968) represented experiment out, and its outcome It is important much of the change implied unemployment point not Friedman in unemployment instance, carried basis units models to a sustained of U. S. history. economists in “stagflation.” leading any long period macro- in detail, let me cite the most a full percentage Earlier, on the under of modern of expectations wo~11d lead also to sustained by many forecasting. purely sustained during to be I have argued all sectors U. S. econometric policies a matter models. treatment during the recent or about endorsed econometric in virtually these arguments fiscal per annum ment argued, and is, of course, in specific of the faulty as 1970, the major 4 percent invariant than review monetary of less than because our experience As recently about of this problem relationships exchange Under simple controversial). explicit change a balanced model. budget ‘Lucas (1976). “Hirsch (1972), de Menil and Enzler(1972). 13 (though For other kinds of How if a policy rates? One can generate one would the of 4 percent fiscal rule? numerical Under answers to questions of this sort from current macroeconomic n~odels, but there is no reason for anyone to take these numbers seriously. On the other hand, neither can quantitative answers be obtained by purely theoretical reasoning. To obtain them, one needs an explicit, equilibrium account of the business cycle. IV. I have summarized, in section II, the main features of the cyclical behavior in quantities and prices. In section III, I have argued the practical necessity of accounting for these facts in equilibrium (that is, non-Keynesian) terms. That is, one would like a theory which accounts for the observed movements in quantities (employment, to observed movements consumption, in prices. In the next section, 1 individiral decision making to .explain, in particular, why the importance. Given this general investment) as an optimizing response will describe the general point of view toward be taken in the remainder of the paper, and will recurrent character of business cycles is of central view, I shall consider in sections VI and VII the way in which relative price movements induce fluctuations in employment and investment. Sections VIII, IX, and X examine the conditions under which these safie quantity responses may be triggered by movements in general. or nominal, prices. Not surprisingly, the sour’:e of general price movements is located, in section XI, in monetary changes. V. The view of the prototypical individual decision problem taken by modern capital theory is a useful point of departure for considering behavior over the cycle, though it is in some respects highly misleading. An agent begins a period with stocks of various kinds of capital accumulated in the past. He faces time: paths of prices at which he can trade in the present and future. Based on his preferences over time paths of labor supplied and goods consumed, he formulates a plan. Under certainty, he is viewed as simply executing a single plan without revision; with uncertainty, he must draw up a contingency plan, saying how he will react to unforeseeable events. Even to begin to think about decision problems of this general form, one needs to imagine a fairly precise view of the future in the mind of this agent. Where does he get this view, and how can an observer infer what it is? This aspect of the problem has received rather offhand treatment in traditional capital theory, and no treatment at al1 in traditional macroeconomics. Since it is absolutely crucial for understanding business cycles. we must pursue it here in some detail. 14 At a purely a subjective which joint impinge probability distribution “uncertainty”) (such agent. the general hypothesis makers in many applications, way has, of inferring hypothesis of the decision any distinction distinction between between “risk” and is, at this level, meaningless. Unfortunately, decision philosophical on the structure (1921) variables The link between is a most complex In particular, as Knight’s formulate random opportunities. and “reality” as seen by an individual agent must over all unknown and future market view of the future of randomness some that a rational but the way it is solved has little effect problem types level, we know on his present this subjective question, formal what an agent’s that economic little subjective is of no help in understanding can be (and today, view of relevant is) understood probabilities. of psychoanalysis, as “rational,” one hopes) are Bayesian content: without view of the future his behavior. To practice agents empirical behavior given a sufficiently economics, of understanding is, this Even psychotic abnormal we need some way (short which decision problem agents are solving. John Muth (1961) proposed subjective probabilities or with “true” “true” with probabilities, probabilities situations in which relevant: which in situations defined recurrent situations event, economic recurrent character similar changes have fairly they stable utilize free of systematic 11 the why business and why it will be reasonable arrangements information In terminology. in terms of economic m Muth’s cycle sense. for collecting In cases to treat emphasized hope as repeated agents they the as reacting are rational future were instances to that they and processing=ation, in forecasting and easily correctable theorists we must as “risk,” or to assume their expectations this likely be a fairly well on the part of agents will cycles can be viewed in a stable and way, biases. Kmght(1921). tbffe;;; Knight’s are rational cycle, as business events, concern are will be of no value. explain of in behavior in frequencies It will m of interest “risk” and will not be will it be applicable may be explainable expectations reasoning considerations of essentially of of subjective this hypothesis “uncertainty.” of rational so that behavior right in doing so. Insofar that 1 1 called agents to be forecast, if any, observable the probabilities situations In such situations, These cyclical Knight coincidence Neither which, by identifying of the events Evidently, behavior. guess of risk, the hypothesis of uncertainty, the psychotic in which have usable content, theory. expectations. one cannot situations useful frequencies calling the assumed rational of value in understanding to resolve this problem observed I am hterpreting the risk-uncertainty distinction as referring not to a classification of types of individual decision problems but to the. relationship betwe~decision maker and 15 VI. In moving will bc helpful from these general to consider considerations as an exan~ple a single worker-producer, confronted each period a good which he then makes to order, he The good he receives with for grunted. in exchange the historical This money, from day to day. Some purchases from work, general or average fluctuate level but simply on a wide variety of goods, he makes on his way home, of prices let us postulate Now rcsqond? does not an increase to the average The answer change, take it different in an hour’s break though this price work no harder, by economic individual prices unfortunate price change mcans. theory If he believes since will be immediate) be the case if each period’s The aliswer producer is willing is highly substitutable the labor change extreme. price for labor he will work longer to transitory price the indicates nearby by Rapping than about leisure periods. and myself (1970); (as would from a fixed the rate at which the If “leisure” on high price actual labor supply response, is an excellent evidence Ghrz or negative. tomorrow. “long-run” in one period Systematic drawing to knowing today we do know that a to a permanent is transitory were an independent labor over time, movements signals that he will are zero the price change in this case amounts to substitute response elasticities about was obtained the price “long-run” supply close early on low price days. Less is known in other, producer must be: who knows’? At this a little less hard. That is, we know that “long run” terminology, What if, at the opposite distribution)? selling price, in his selling price, we know from much evidence and probably (very in today’s How will this hypothetical which would enable one to imagine what the producer movement change of 10 percent of past prices. given I have said nothing permanent leisure I shall not be is “money”; from day to day. as compared thinks how or several days later. I ~SSLIII~~ for now that he holds no other 1 assume also that this agent lives in a cycle-free world, in which the securiti:s. point, selling price, determines for this arrangcmcnt, is spent price for per hour. That is, then goes home to relax. for the effort reasons in turn, theory, it agent. 13L Imagine with a given market his current many hours to work that day, sells his produce, concerned specific at a fixed rate of output to his place of work, observes COIR~ to more a “representative” at the and Becker days and responses but what substitute aggregate (1975) for level reached 12 Many of the arguments in this and subsequent sections lwe been developed more explicitly elsewhere. The closest sin e parallel treatment is in Lucas (1975). See also Pbelps, e_tal. (1970), Barre (1976), Sargent and Wallace (1 d 73, Sargent (1976). In what follows, I will not document particular arguments, nor will I attempt to apportion credit (or blame) for ideas discussed. 16 the same conclusion induce workers Saturday, two conclusion, at a disaggregative to shift weeks and this its probabilistic of this evidence, holidays in March level. The small premiums and vacations (take rather than in August) evidence “cas~~al” simplicity: holidays one would predict is somewhat Monday more required to off instead of point to the impressive same because of are known to be transitory. On the basis highly elastic response to transitory price a . changes Before dealing for business price cycle with complications theory. fluctuations exactly what intelligible prices with large we observe effects, our aggregative generally; the example not in responds output and rests unintelligible on note its promise us who The description observations refers let a producer fluctuations over the cycle, substitution us go slowly: to this example, I have described on economically “disequilibria.” refer to co-movements to relative to small employment: Yet let of output price movements and in a stationary environment. Before facing the example seems just mart’ producers this difficult considered. realistic to by quantity to be There seems as signals of current me harmless and interchangeably. equilibrium let from a descriptive of accurate determination relevant A second variation when producers reason on it often conveyed to and the like. to focus exclusively on price increase and sales increase however, rigorous set prices is extremely difficult, than consider a worker- cycle behavior these being rundowns, functions, analysis of exist. is easy to carry out. Rather separate variations of view, At this verbal level, it seems to terms surprisingly, to business one could information demand. to use the some point inventory substantive and future Somewhat us consider demand new orders, compelling no and no examples entrepreneur, thinK changes: prices issue, First, introduce firms, and consider labor and product markets separately. In the present context, this would introduce a distinction between wages and prices, and raise the issue of riskallocating permit arrangements the study None of these peripheral the tendencies. employers different is without cycle theory. neither This suggests Accordingly, 130ne but a central “wages” questions for business cycle, ments between of possibly do that any attempt I will proceed and “prices” interest, Observed they ‘exhibit role in an explanation as though and l3 workers. information It would but all are, in my opinion, real wages are not constant consistent pro- or to assign systematic of business also sets for firms and workers. over countercyclical real wage move- cycles is doomed to failure. the real wage were fixed, using the terms interchangeably. such arrangement is the practice of “laying off’ workers. See Azariadis (1975). 17 Additional LWS variations can be obtained of the worker-producer’s attempted, for example, in job search. some other of substitution is little when unemployed than of the elasticity movements, “leisure” unemployment not the reasons matter, a testimony there that that measured the important with why that the unwillingness is more Nevertheless, at all. Economically, of employment i& in the importance that search is less costly for that or, have substitues one illustrations. in job search, various as time engaged that one’s belief employed, any activity I suspect Indeed, doesn’t when unemployment plausible time is spent among Many writers away from work shows by some measures and price as enjoying if one substitutes that much is the, magnitude measured and experience is bolstered evidence unemployment wage to interpret Certainly, activity, by distinguishing time when he is not working. respect issue to transitory elasticity is what to speak of workers to the force of Keynes’ it is. in recession insistence that is “involuntary” want than a response to observed phenomena. One that people !& depressions! Of course, the hypothesis to suggest of a cleared labor observation that people market carries with it no go hungry suggestion, SLIC~I in cleared food markets any more than the suggests that people enjoy hunger. More complex variations VII. on this example kinds is introduced. Let us do this, retaining over time in the general level of prices. Three possibilities can be stored the account surely labor of interest as finished supply relative sketched storage also dampens in the elasticity to price, and an increase in the real sales-price As a second suppose production future to acquire periods. the same As a’ third, effect. may be considered Since earlier, provided the producer which it is clear that neither the new capital can be applied will On the industry The net result can use a part of his current will raise his output-per-hour transitory of these options his original to production, will have vanished. 18 in school do not differ of purely with is with respect elasticity. the producer two possibilities was satisfied The producer movements. s~lppose he can take a course these made it appear profitable above. of employment-production as one. In the example discussed time a machine production seems to work against is precluded. price likely to be a reduction possibility, of various of stability for sale later when price is high, smoothing to the case where this behavior capital that current This possibility co-movements in low price periods level, however, arise. First, suppose goods inventory. of price-output produce arise when still the assumption in all which will have economically, they price movements, will ever be exercised stock -- of capital. By the the price movement which Current capital relative price accumulation permanent. In insensitive moving movements when, this case, to price at the however, movements. systematically a situation, engineers variables (the transitory observed directly; knowledge change, his these decisions components, depends leisure our increase in unobserved. factors: and (price) in what changing fundamental which cannot be together with his sources of price Based on calculation, out producer he takes to be an average Under supplied, expansion in productive symmetric; the responses optimal the way he interprets concerning assumptions his response a of the to face stochastic of transitory response to and permanent price the information intertemporal consistent to an unforeseen a decline capital is taken as a mix His his preferences evidence, labor turns hypothetical is describable and consumption. and available of price) movements, be elements. to engage in more probability decision it must in the two components. conditional the obliged of the two unobserved the movements be to the two extremes. both changes, price as will and permanent movements on and employment a single variable components observed implied which on two from importance infers appropriate arise these surprisingly, variability, these will find himself he observes and permanent To recapitulate, price are a mix of transitory movements this employment price movements, from to Not noted, of relative of the relative solution as I have effect are regarded in the direction he imperfectly decision. maximal they investment the producer time; their extreme, to observe call “signal processing”: through have Thus, the case that such movements In such will opposite in finished movements contained with rational price increase goods of all kinds. This are the opposite. 14 of behavior is a sizable inventory, accumulation to price decreases in substitution and an behavior is VIII. It economy goods to comprised and subject go behind underlie is time price them. think of of similar situating agents, though to different individual movements to the These changes this representative of course price movements. changes are occurring producing time in an different To do this, one must in technology all the producer and taste and, ‘indeed, which their 14 What is happening to consumption expenditures as these employment and investment responses take place? In his critique of equilibrium business cycle models, Grossman (1973) argues that consumption must necessarily move in them direction from labor supplied. Since this is not what is in fact observed over the cycle, it would indeed by a serious paradox if a negative correlation were a consequence,of utility theory. One M derive it,for special cases (see Lucas, 1972, Fig. 1) but this implication is certamly ma general fact for optimizing households; it does & for example, follow from Rapping’s and my (1970) theory or from that of Ghez and Becker (1975,ch. 4). 19 importance ments to individual which agents constitute to the general, lead relative, reducing costs of producing business not production of other reduced economy, small SLICII in the mere presence, to total per investments. ous!y. Such shocks of a and away from the of one good in a complex modern in any given period, There will be much affect each “averaging ments fit the description reason seriously, It is surely there many price movements instances of the economy in section (other of simultane- and they will in- They will not, however, sketched for a large their work weeks in the way I have described, in the aggregate. cycles in individual possible have been sectors why one we call business of conditions tight. all, or many, will not cancel fluctuations movements important movements to feel an urge to increase More which to countercyclical the production shifts the most is not entirely duce output procyclical output. in technology, of the purchase se, of unpredictability spontaneously to supply which SLICII of the general Yet this argument of agents shocks possible move- should, A new benefits, Moreover, of movements movements. in favor others. of this sort is, 1 think, seek an explanation and expand shifts on relative Cancellation number these minor across markets. cannot markets. Taste will be a large number effects Yet price into the good which goods. in importance out” of cycle. general expenditures there by far the relatively an old good or making new one, will draw resources involve dominates II: all supply lead to moveshifts will lead things being equal) in contrast to the we observe. It is, then, possible to situate our hypothetical producer in a general equilibrium setting, in which his price and output fluctuate, yet aggregate levels do not. His responses to these relative responses price to general prices movements movements which will mimic the aggregate constitute the business have then a coherent model, but not one which as yet accounts phenomena to be explained. This model can, without difficulty, permit general, supply-induced blance to the modern Before most of present leaving the in such a sdtting. a national to the concert finance By the time like these, of stable troubles and Will consumers joke? education, one has acquired Will a doren hobby? or tide it is worth economic years stressing agents 20 design, in piano over next month’s necessary to resolve be or lead wages strike? questions one is committed. and magnitude, in the year ahead of training that would Will this week’s overtime the family the information to risks of this nature worked bear no resem- take to a novel automobile it is too late; one way or the other, actually but these aggregates, challenges stage, or just a pleasurable a child’s Compared the hours fluctuations, We cycle. this world risk which will it become help business output cycle. for the general be modified to the question will be 1.03 times of whether what one plans for now, or .97, seems economic theory, imposed a minor on an otherwise the transfer one, and seems so because we are accustomed stable of abstractions involve fatal distortions to think of business environment. useful it is. In aggregative cycles as a kind of risk Such habits for some purposes of thought into contexts reflect where they of reality. IX. Let us now drop point of view in the nature given of the in his or a transitory a situation which, producer’s part. price individual as will relative expansions, price the responses at the aggregate be solved. the change Before, a relative price that al prices are changing, lead to no real response on the and transitory relative at the time, neither General movements price increases, can exactly in the same direction as such ordinarily traders not know as they in published those prices and carefully, at all. Of the many behavior is no reason of most sources for traders By the same reasoning, Within price price increase than will be con- output, seem and investment importance to specialize agents, their not how An optimizing many trader problem less so, and most to him, the business of no special could world, every day, nor would useful. be of the aggregative implausible: to his decision of less importance is, for most movements of a multi-commodity all prices particularly price the context may of risk of importance generally general movements real decisions indices those general In the reality want to observe price even during in real terms in prices, that assumption t& price of goods? in demand earlier, over markets. over the actual cycle. argument this described to cancel (this is what a general will be expanding are occurring. used, no one would will process declines will be co-movements to this changes will not tend increases level, just as is observed models find and technology will observe more It is essential agents’ will induce will observe The net effect diagnosing be distinguished. price increases producers but more and therefore aggregate would From a slight a permanent out with certainty to taste to general tracting. there be sorted increases, means), frequently mean one. Now, it can also mean cannot To be sure, some traders which must could diagnosed, only and investment. Unlike however, in average prices. involves Yet, for the same reason that permanent responses perceived this problem price” and general movements employment these “own if correctly movements relative of stability producer, of the signal processing movement change the assumption prices not cycle and importance, own information most systems and for correctly. one can see that sustained in the way that transitory 21 inflation price movements will not affect do. Nothing is easier than to spot and correct involve no changes information. for There what inflation in agents’ may, of course, it is; about as though Changes effects on as often, placed bias in forecasts. Such corrections systems or in the costs of processing be some lag in diagnosing agents will incorrectly sustained inflation perceive a transitory will have more fundamental it were sustained. in the agents’ “weights” systematic information degree of price information variability processing on price information idea is that one trusts “noisy” behavior, because in forecasting future they affect prices. the The general price signals less. .r The aggregate more complex Investment reasons or average response as one considers decisions will be distorted as will employment, to general investment price movements becomes as well as employment responses. by general price movements, and in the same direction for the same as the responses induced by relative price movements. Further investment complications affects seen to extend follow, future capacity, in time, perhaps however, from the observation and hence future even to amplify, detail, imagine prices. that current This effect the initial effects can be of general price movements. To spell this out in more would, if correctly Sooner or later, then, this adjustment than not perceive perceived a relative As a result, employment information diffuses mistaken. and investment through postponing unsystematic however, both or short-term shocks of increase. however, to prices which generally. more traders in their favor. Through time, as price will see they have been capacity retards initial shock. the occurs in prices permanent, these traders the added recognition some event Initially, possibly the economy, the that an increase will occur. price movement, In the meantime, generally, by all. induce can lead to much price increases In this longer way, swings in prices. In addition, of capacity. have to become There is no describable general since reason to expect scenario, optimal automatically of general less than normal crucially price is a downturn recognition as a “crash,” This depends there When inflation built in to this expansion does occur, for a time while capacity this readjustment investment readjusts to come will downward. rapidly, or to be or “bust.” like the earlier on the confusion movements. This investment policy description of the employment on the part of agents is especially clear in the between case has a great deal of “smoothing” 22 response, relative and of investment, built into it: since investment is a long-term to be relatively This of purchases contribution For negative, investment and often to what stems ment. someone who amplitude response shocks to skepticism cycle. rates of return in hundreds a weak added is often the situation the capacity is, at the level at which amplitude faced by agents. variable, A quick, current often response the key to a successful is clear to everyone to meet invest- is too late; the high demand. response decisions movements in durable insist on the minor are highly of percent. “signal” until as to the can moderate movements level, to be a high-amplitude to still higher How risk to the general risk situation waits at the aggregate only to what seem Here again, one must projects, else has already appears, grounds, business lead to the high-amplitude measured to others The agent in the are observed? of economy-wide individual on serious effects in prices which it will respond price shifts. has led, accelerator movements goods commitment, relative observation importance cyclical permanent are made, in returns What pattern to low- a high-amplitude to individual invest- as repeated fluctu- ments.15 XI. I began section ations a certain typical a competitive by agents rationalizing sections. output, pattern employment to price the observed any we know prices direction secular and output movements movements do extremely in aggregative economics, of effect kinds appropriate as rational with Since in are chosen to begin by or optimal responses in the preceding five of price movements. of money or the quantity of various it seemed associated other variables. This has been accomplished 1 turn next to the sources For explaining cycles of output, in prices and movements, quantity price movements. in the quantity of business and the composition of co-movements economy, in response to observed either II with a definition in employment. in prices and is not sensitive of money. in this relationship; generally, secular movements well. This fact is as well established I6 There to how one measures is no serious no one argues as doubt as to the that the anticipation of 15“Austrian” or “monetary-over-investment” business cycle theory (see Haberler, 1936, or Hayek, 1933 ) was based on this same idea of mistaken investment decisions triggered by spurious price signals. However, the price which this theory emphasized was the rate of interest, rather than product prices as stressed here. Given the cyclical amplitude of interest rates, the investment-interest elasticity needed to account for the observed amplitude in investment istoo high to be consistent with other evidence. 16Friedman and Schwartz (1963). 23 sixteenth-century to finance inflation rcfcrs to averages strong to be ignored: real variables that. sent Columbus it. This evidence over much longer periods, we have accounted “long run,” general in the quantity of money. enough to be quantitatively shock as the force triggering The direct indicate that however, more between general price This connection identifying general one could function far from would between to a monetary money, episodes money-induced.17 and other to prices, cycle theory. describe short-term of lagged movements output, appear to In general, variables is agreed to be evidence linking is encouraging from money To see why, recall the theoretical and economic activity as skctchcd that the signal processing from observations by agents. of link above. problem of a few individual of prices Now s~lppose it were true that general price in some published movements the signal processing to the point by a simple. monetary problem aggregate. to be solved fixed Then, by agents trivial, they could simply observe current monetary aggregates, -) the predicted current and future price movements thev imply,and cor- rect their behavior for these tight relationship belticcn relationship These answer units changes money at all between remarks long and variable depending diffcrcnt price would suggest that one should by aggregates “Again, see Friedman explain some and changes e describe expansion monetary but closely and Schwartz (1963). 24 effects work with into the system, with way is selected. This “state” aggregate, related and can occur in a variety on which the monetary periods, in real variables. It seems likely that the is “injected” depending unobservable over short periods monetary little is known. that a monetary implications The result would be a very over even very short movements on the way the money response determined observed these do not, of course, lies in the observation perfectly. and prices, lags. On this question of ways, being changes are large bc calculate no are on the hypothesis difficult, point extreme in the short-term to be solved perfectly being correlations and these price movements was too difficult in money to “long and variable lags.” movements rested movements we know from cycle. recoveries money business price movements; arise primarily to read. Certain and in particular view of monetary among All these arguments this weakness activity, are too interesting. terms, Paradoxically, economic connections cyclical and the gold cycles, since it of co-movements Moreover. on short-term depressions in Friedman’s to general price movements difficult the link between subject, but the indirect the real business evidence is much to business for the pattern over the cycle as responses in the and prices to the New World to locate has no direct connection of the economy loosely secularly. related as to XII Let me sketched fluctuating tastes and studied agents recapitulate the co-movements behaved We then in a monetary individual comovements summarized wonders price movements. among aggregate in section why it seems which theoretical pass the seems ordering which posed rather to undo them in way. To date, Adelmans for economic policy. By seeking rather policy are induced increased variability and variability would There explicit Simons, then purpose, more of Henry fluctuations increase remain is no prima 18Pmceedin further of Sargent’s $1976). if unsystematic source generate of “noise” a pattern of embarrassingly simple: which terms, to the hope that this can be done model has at the same time, could My own guess would be that business cycle theory the theory much of the above is simply’an attempt the implicit the policy model and stability other of business scope by the theory. promises the smoothest 25 of activist cycles, one serving Insofar as no social to reduce aggregate, real however, that come real monetary variability out on this limb, it is likely that such a “successful” to of governmental instability, is no doubt, facie case that this residual critics on the monetary There underlying account be rationalized by gratuitous even under enough years off.18 limitations monetary no equilibrium and which, an equilibrium welfare. and time equilibrium Friedman, might at. I think economic easy to guess at even when Milton severe one to arrive at it. Yet of observed policy of a successful state. Indeed, and make countercyclical sizable, a Revolution (1959). are, I think, here in advance emerge information the observations however, these standards by the itself is in a preliminary aggregative with to match in the behavior to lend confidence meets The implications accepts would what has, in fact, been arrived is nothing exist of the sort outlined proposals which is to theory relative prices, their incomplete appears success in this sense is five, but not twenty-five understand changing economy result cycle an economy an additional series which to be necessary and rigorous test this adding not to overstate examples been developed on account precludes in an explicit business and prices and utilized The the II. this be careful of by imagining continually in quantities aggregate, it is fairly clear that there series implying superimposed retrospect, one must features We began in their own interest movements In main sections. and technology, effectively. to the in the preceding and fiscal policies. would be better dealt model will be a close descendant with by centralized, governmental policies than by individual, decentralized responses.19 In view question of this that in a democratic must lack of novelty to ask: why be able do we need society in the realm the theory? it is not enough to believe unemployment why rate fluctuates between, both situations are attainable, and it is clear three than at ten. It is also clear that government which to explain of these natural, then. covering situations than which advocating their even when now, appeal adoption? the is understandable The subject of scientifically should instability. should As long as the business economic theory. both determine how business positions cycles that some then economics. and is most social forty evident, science years its offers by flexible arc in possession them to determine, if many of these cycle remains tenable. and of a at any time, who are not profcssion- beliefs. This in itself settles in stabilization to offset “in apparent There to become are inherently be eliminated part or actively appear of dis- and economies the role of government its own disruptive situation, state of affairs. enabling to the latter at be more as that of Keynesian economists be. It is doubtful the that are happier economics market that is have much to do with desirable has had can only and knowledge today, in which It follows time. What could the hope that which as to whether be to reduce more a fair I think, to be right; one’ people of this promise share ideas: responses: hold, in the dispute the public related tested responses ally committed little most policies of the existing fluctuations governmental what these to all who literate two to violent forceful body with to emptiness rationalization economically comfortable that This was the promise scientific oneself We live in a society at any particular will lead it seems answer, say, 3 and 10 percent. to view the task of aggregative policies more than elegant one is right. prevails of policy, The general seems private contradiction” policy sector to to bc no way to are to be dealt with short of understanding what they are and how they occur. 19 That is to say, active countercyclical policy would require the same kind of cost-benefit defense used in evaluating other types of government policies. 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