European Economic Review 35 (1991) 1543-l 557. North-Holland Exchange rate policy and wage formation in an economy with many trade unions* Steinar University Received Holden of Oslo, N-031 7 Oslo 3, Norway December 1989, final version received November 1990 Exchange rate policy may confront governments with an important credibility problem. While there is usually a long run gain from abstaining from devaluations, there may also be a short run benefit from a devaluation. This short run benefit may cause expectations of future devaluations, resulting in wage and price rises that make the expectations self-fulfilling. This issue is analysed within a model with many trade unions. If the government pursues a nondevaluation policy, the trade unions gain from voluntary wage restraint, However, if the nondevaluation policy isn’t credible, the cooperation on wage restraint may break down. 1. Introduction Since the collapse of the Bretton Woods system, exchange rate policy has been an active part of the economic policy of many governments. Devaluations have been used in order to improve a country’s competitiveness, so as to reduce any current account deficits and increase employment. However, frequent devaluations also involve considerable costs, as wage and price setters will learn to expect future devaluations. Thus some countries, like Denmark, have explicitly announced a non-devaluation policy, so as to influence expectations and break the vicious circle. A problem with a non-devaluation policy is its credibility. Wages are often determined in annual negotiations, while the exchange rate can be changed at any point in time. Thus, a government may feel tempted to exploit the short run rigidity of wages, and devalue in order to obtain a short run gain in terms of improved competitiveness. Problems of this kind have been discussed in the literature on credibility of *This paper is part of the research project ‘Wage formation and unemployment’ at SAF Center for Applied Research at the Department of Economics, University of Oslo I wish to thank Michael Hoel, Karl Ove Moene, Oddbjorn Raaum, Jon Strand, two referees and participants at presentations in Barcelona and Bode for helpful comments on earlier drafts. C@14-2921/91/$03.50 0 1991-Elsevier Science Publishers B.V. All rights reserved 1544 S. Holden, Exchange rate policy and wage formation government policy, see Blackburn and Christensen (1989) for a survey.’ Compared to more traditional analysis of government policy, the game theoretic approach of this literature has the advantage that both government policy and the behaviour of the private sector are endogenised, allowing for explicit focus on the interaction between them. However, a problem with this literature is that the private sector is treated as a single player. This makes the existence of a conflict of interest between the government and the private sector, a crucial assumption in this literature, less obvious. After all, the individuals in the private sector and the political electorate consist of largely the same people, and will therefore have largely the same preferences. In the literature one therefore usually assumes that there is a labour market distortion which is the cause of this conflict of interest. But this assumption begs the question of why the government does not pursue a first-best policy and remove the distortion directly. Once one allows for several agents in the private sector, the situation is entirely different. Each agent will be concerned with the effects on its own welfare only, and disregard any externalities on the aggregate economy. The government, on the other hand, will mainly be interested in the aggregate outcome. If the wage setting takes place at a decentralised level, externalities will arise, and the government will not be able to remove these. This paper analyses the interaction between wage formation and exchange rate policy in an economy with many trade unions. Compared to the literature referred to above, the assumption of many trade unions has two main virtues. First, as discussed above, the existence of many agents in the private sector allows for an explicit modelling of the externalities in the wage setting. Because of this, and because the preferred outcome of the government coincides with the preferred outcome of the private agents, it is also possible to draw conclusions on welfare implications. This contrasts with most of the literature referred to above, where, as argued by Blackburn and Christensen (1989), conclusions on welfare implications seem doubtful as long as the preferences of the agents in the private sector remain unmodelled. Secondly, for unionised economies, the assumption of many trade unions seems much more realistic than the assumption of a single central trade union. Even in countries like Norway and Sweden, which are often considered the most centralised, the largest unions’ confederation LO represents only 36 (1985) and 52 (1987) per cent of all wage earners, respectively. Other confederations cover 23 per cent in Norway and 37 per cent in Sweden [cf. the country papers in Calmfors (1990)]. ‘The bulk of this literature focusses on monetary policy atomistic private sector, following Kydland and Prescott (1977) A smaller part of the literature [cf. Calmfors and Horn (1985) analyses fiscal policy or exchange rate policy in a game between trade union. in a closed economy with an and Barro and Gordon (1983). and Horn and Persson (1988)], government and a single central S. Holden, Exchange rate policy and wage formation 1545 An important premise of this paper is based on a conclusion drawn by among others Calmfors and Driflill (1988) that centralised wage setting leads to lower real wages than does wage setting at industry level. The basic intuition is the following. If wages are set at industry level for each union independently, then each union will obtain a high real wage level, leading to a high unemployment rate in the economy. This involves negative external effects on the welfare of other unions. However, if the unions act cooperatively, then they will internalise the negative external effects and thus set a lower real wage. If the unions have the opportunity to enter into a binding agreement on wage restraint, or to negotiate wages jointly, then the unions could be expected to achieve the ‘low’ wage level they prefer. But either of these alternatives would make the case with many unions similar to the case with a single central union. As argued above, this does not seem like a realistic description of the world. Thus, I explicitly exclude both alternatives. Without any of these options, it may be difficult for the unions to coordinate their wage setting, as each union will be tempted to deviate from an agreement on wage restraint and set as high wage. That this is a real problem, can be illustrated by the statement by the leader of the Norwegian unions’ confederation LO that the total wage increases in 1986 had been too high [Halvorsen (1986)]. I analyse the question of whether union cooperation on wage restraint can be sustained as a non-cooperative equilibrium in a repeated game. In each time period, each union has the possibility of defecting from the agreement on wage moderation and setting a high wage level, thus obtaining a short run gain. Such defection will lead to a breakdown of the agreement. As is standard in repeated games, cooperation will be sustainable as long as the short run gain from a defection is less than the subsequent loss from a breakdown of the cooperation. The loss, i.e. the outcome of independent wage setting compared to the outcome of cooperation, arises through a higher real wage and a higher unemployment rate. However, the adverse effects on unemployment will be mitigated if the government pursues a devaluation policy, as the real wage will be reduced towards its full employment level. Government policy will therefore affect whether or not unions are able to cooperate, as a devaluation policy may make the costs of independent wage setting so small that cooperation is not sustainable. The idea that industry unions may cooperate to achieve wage restraint is neither surprising nor new [cf. Danthine and Lambelet (1987)]. Yet the issue of how this cooperation may come about has received little attention. Because of this, there is no framework for evaluating how such cooperation may be affected by government policy. The present paper shows that credibility of government policy can be crucial for the existence of union 1546 S. Holden, Exchange rate policy and wage formation cooperation on wage restraint, and that the policy will be credible only if the government is sufficiently patient. The basic setup is similar to that in Holden and Raaum (1989). However, Holden and Raaum (1989) contains a more general discussion of union wage moderation, and no analysis of the effects of varous exchange rate policies. Furthermore, this paper extends the basic setup considerably, by including government policy as an endogenous part of the model. The paper is organised as follows. Section 2 sets out the macroeconomic model, which is kept as simple as possible in order to focus on the game theoretic aspects. The government’s and the unions’ policy alternatives are presented in section 3. In section 4 I discuss union cooperation within a repeated game setting, while in section 5 I extend the model by endogenising government policy. Finally, there are some concluding remarks in section 6. 2. The model We consider a small open economy, with K 22 symmetrical industries, each consisting of many identical firms. In each industry there is production of a different traded good with a given world market price. There is also a single union in each industry, covering all workers in the industry. The economy’s exchange rate is determined by the Government. The Government cares about its popularity, which depends on the employment level and the rate of inflation. These variables are influenced by the nominal wage in each industry, which is set in a wage bargain between the union and an employers’ federation in each industry. The leadership in each union also cares about its popularity, which depends on the after-tax real wage level and the employment level in its industry. Unemployed workers receive an unemployment benefit which is financed by a proportional tax on all labour income in the economy. Thus, higher wages in one industry will raise aggregate unemployment and the tax rate. (To keep the analysis tractable, this is the only external effect that is incorporated in the model.) In each time period, the nominal wage is determined simultaneously in each industry; afterwards the Government sets the exchange rate. This time structure captures the fact that wage settlements are made at discrete intervals while the exchange rate can be changed at very short notice. As in Horn and Persson (1988) I rule out any indexing in the wage settlements by assumption (this conforms with the empirical observation that wage indexation is rare [cf. Oswald and Turnbull (1985) and the country papers in Calmfors (1990)]). Throughout the paper I assume that all players have complete information. An important assumption in this paper, as well as in much of the literature referred to in the introduction, is the existence of short run nominal wage S. Ho/den, Exchange rate policy and wage formation 1547 rigidity. Clearly, without nominal rigidities, a devaluation would be entirely useless, and credibility of exchange rate policy would not be an issue. However, Poterba et al (1986) present evidence for the existence of nominal rigidities in the U.S. and the U.K. Furthermore, the introduction of Calmfors (1990) summarises evidence from the Nordic countries showing that all major devaluations but one during the last two decades have resulted in at least a temporary improvement of the competitive position. World market prices are assumed constant over time and normalised to be equal to unity in all industries. This implies that the domestic price is the same for all goods, P,, and that it is set directly by the Government via its exchange rate policy. In each industry, labour demand is given by Li,=L(wyPt), L’<O, (1) where I+$ is the nominal wage in industry i. At the aggregate level, we define total employment L,= Ci Lit, and the average wage w=Ei ~*Li,/L. If the wage and price levels are equal in all industries, then total employment is given by L, = N( kt/P,) = Ci L( i+/P,), N’ < 0. (2) The total labour force in the economy is normalised and set equal to one. Hence, there will be full employment if P,=ZW,, where I have defined Z= l/N-‘(l). The Government’s per period popularity G, is a strictly quasiconcave function of the employment level and the rate of inflation, G,= G(L,,fl,), defined neglect assume (3) over L,E [0, l] and IIt= P,/P,_ 1 - 1 E [0, co). (This implies that the possibility of revaluations). Concerning the partial derivatives that they are continuous and that G,(L,,ZI,)=O for L,= 1, G,(L,,17,)>0 I I for L,< 1, (4) G2(L,, Ii’,) = 0 for ITI,= 0, G,(L,, H,) > 0 for II, > 0. Thus, Government popularity is maximised when there is full employment and zero inflation. Furthermore, if full employment and zero inflation are not attainable simultaneously, then the assumptions on the partial derivatives ensure that the Government will set the exchange rate so that there are both a strictly positive rate of inflation and a strictly positive unemployment rate. 1548 S. Holden, Exchange rate policy and wage~ormation The Government’s popularity: f overall objective is to maximize the present value of its 6pGj, (5) j=t where 6, is a discount factor. 6, is assumed to include an exogenous probability 1 - pc that the Government is replaced by a new identical Government (so the game finishes for this Government). (A better approach would clearly be to endogenise this probability, but this would complicate matters considerably.) Thus 6, = pc/( 1 -i), where i is the pure interest rate. The per period popularity of the leadership of the union in industry i (hereafter referred to as union utility) is an increasing function of the aftertax real wage level and the employment level in the industry, or where r, is the tax rate. The overall objective of each union is to maximise (7) where the discount factor of the unions is 6u=p,/(l -i), and 1 -p. is an exogenous probability that the leaderships of all unions are replaced by new leaderships. A replacement of the Government is assumed to be uncorrelated with a replacement of the leaderships of the unions. Unemployment benefits are assumed to be taxable, set in nominal terms in the beginning of the year, and denoted B,. In this case, the tax rate is determined by T,ci ~,Li, = B,( 1 - Z,)( 1 - L,), (8) where the left hand side shows the tax proceeds from the employed workers, and the right hand side shows total benefits net of taxes. Eq. (8) yields (1 - T.,)= Ci wilLi,/Cci M/;~Li,+ B,( 1 -L,)]. We can substitute (9) into (6), to obtain To exposition, simplify the I assume that, (9) if wages are identical in all S. Holden, Exchange rate policy and wage formation industries, level. then (10) is maximised 3. Union and Government 1549 when wages are set at the full employment policy alternatives We first consider exchange rate setting in one time period in isolation, and when all unions have set the same wage. Full employment is achieved if the Government sets P,=ZII$ while zero inflation will be realised if the Government holds the exchange rate fixed, P, = P,_ t. If w = P,_ l/Z, then full employment and zero inflation can be achieved simultaneously. I shall distinguish between two types of exchange rate policy. Accomodating policy is to set the exchange rate at the level which is optimal when one period in considered in isolation, taking as given the wage level already set in the industry bargaining. That is P:’ = argmax G(L,, n,). (11) From the assumptions on G it follows that P:’ is unique. As noted above, it also follows that if W,> P,_,/Z, then Z~>P~>Pt_l, that is, the Government will set the exchange rate so that there is a strictly positive rate of inflation and a strictly positive unemployment rate. Strong policy is to hold the exchange rate fixed, so that there is zero inflation, i.e. p;=p,_,. (12) We now turn to the industry wage setting. The outcome of the industry wage bargaining is assumed to be given by the Nash bargaining solution, that is (13) subject to Li, =L( WJPJ, where /I is the bargaining power of the union, n, = (P,F(L,) - Wi,Lt,)/P, is the real profits of the firm, and U,, and rctO are the parties’ respective disagreement points. Following standard practice [cf. Jackman, Layard and Nickel1 (1990)], I assume that the disagreement point of the firm is zero, rr10=0, while the disagreement point of the union is an increasing function of the after-tax real benefit level and a decreasing function of the unemployment rate (aggregate wages are omitted for simplicity, but this is of no importance for the results), U,,= U,(B,(l -Q/P,, u,), where u,= 1 -L, is the aggregate unemployment rate. The solution to (13) is a real wage equation 1550 S. Holden, Exchange rate policy and wageformation where h, >O, h, ~0, while the sign of h, is indeterminate (subscripts denote partial derivatives) (The proof is available from the author on request). As the industries are symmetric, the outcome of the wage bargaining will be the same in all industries, so we can omit subscript indicating industry. Substituting out for the aggregate unemployment rate and the tax rate, and straightforward calculation yields the reduced form wage equation where, under reasonable assumptions H’ r 0 (derivation is available from the author on request) [this is also the standard result, cf. Jackman, Layard and Nickel1 (1990)]. The intuition here is that higher real benefits will raise the payoff of the unions during a dispute, which strengthens the bargaining position of the unions. If unions and firms expect the Government to pursue an accommodating policy, the outcome of the wage bargaining r/v: is given by W;‘/P;‘= H(B,/Pf). A crucial assumption on Wf is that W: > P,_ ,/Z, so wage setting by each union independently will lead to unemployment even if the Government pursues an accommodating policy. If the Government is expected to pursue a strong policy, the outcome of the wage bargaining Ws is given by Ws/Pf= H(B,/Pf). As Pf> P;“, it follows that B,/P;‘<B,/Pf and thus that Wf/P;” < Wf/Pf, so the real wage level will be higher when the Government is expected to follow a strong policy. The reason is that the price level is lower under a strong policy, making the real benefit level higher which strengthens the bargaining position of the unions. If the Government pursues an accommodating policy, total employment is L~=~(W~/~~)=L~ < 1. Let UA denote union utility in this case. If the Government pursues a strong policy, total employment will be L,= N( Wf/P;) = Lf < L;4. Us denotes union utility in this case. As Lf < Lt, it follows that Us< UA, i.e. if there is independent wage setting the unions are better off when the Government follows an accommodating policy. The intuition here is that all unions lose from the high wage level and high unemployment rate under independent wage setting. However, if the Government follows an accommodating exchange rate policy, the real wage level and the unemployment rate will be lower, and the loss will be reduced. As the industry unions realise that independent wage setting leads to a bad outcome for all, they will wish to come together and agree on a lower wage level. Such an agreement can be implemented through the industry wage bargaining. The employers will clearly not object to a wage level which is lower than what each union can enforce through industry bargaining. The unions will prefer an agreement on W: = P,_ ,/Z. The Government will then set P,=P,_ ,, and the outcome will be full employment and zero inflation. Let U’ denote union utility in case, where UC> UA. S. Holden, Exchange rate policy and wage formation 1551 Even though the unions have agreed on a lower wage level, each one of them will nevertheless have the opportunity to deviate from the agreement and conduct a normal industry wage bargaining. If union i alone deviates from cooperation, it will obtain the wage level W$ given by W!JP, - I= h&/P, _ 1) 1 - Ld, 1 - ?d), (16) where L”=C L(w:/P,_,)+L(w~*/P,_,) j#i and 1-zd= w: [ c L(w:/P,_,)+ j#i j#i W: 1 L(W:/P,-,)+ [ W~*L(W~*/P,_,) I/ w:L(w;t/P,_l)+B,(l-Ld) 1( and where I have assumed that each industry is so small that the Government always set P, = P,_ 1 if only one union deviates from the agreement on W: (this assumption simplifies the exposition without affecting the substance of the paper). Define Vd as the utility of a deviating union, when all other unions stick to the agreement. As a deviating union benefits both from the wage restraint in the other industries and from its own high wage, we have Vd> V’. 4. Conflict or coordination? We now look at one time period in isolation, where Government policy is exogenous, but without any restrictions about whether or not the unions cooperate. Clearly, the unions would wish to cooperate, as this gives a higher payoff. However, given the actions taken by the other unions and irrespective of what the Government will do, the best action for each union is to deviate from any agreement and obtain as high wage as possible. Thus the unique Nash equilibrium in a one-shot game is independent wage setting in each industry, resulting in W: or Wf, depending on the policy the Government is expected to pursue. Consider now the complete game, with an infinite number of time periods, and the following strategy for the unions. (1) Cooperate until some union alone deviates from cooperation. S. Holden, Exchange rate policy and wage formation 1552 (2) If some union alone has ever cooperate in the future. deviated from cooperation, then never Thus, if one of the unions deviates from the agreement, all unions revert to the one-shot Nash equilibrium. Let us first assume that the Government follows an accommodating policy. The strategy specified above will support cooperation as a subgame perfect equilibrium if Ud-uc~S”(UC-UA)/(l-S”), (17) where the left hand side indicates the immediate gain from defecting while the right hand side shows the subsequent loss from lack of cooperation in the future. If the Government follows a strong policy, the corresponding condition is Ud- UC5 S,( UC- V)/( l-6,). Proposition I. There such that cooperation (18) exist two critical values c?~,S~E(O, l), where dA> 6’, is sustainable as a subgame perfect equilibrium [f and only if (i) c&,Z;~~ and the Government follows an accommodating and the G overnment follows a strong policy. policy, or (ii) fi,zt? Proof. See appendix. Thus, there may exist situations (if S’<S,< SA), where union cooperation is sustainable only if the Government is expected to follow a strong policy. In these situations a ‘strong’ Government will be able to achieve both full employment and zero inflation, while a ‘weak’ Government will achieve neither. The reason is that under an accommodating policy the situation with independent wage setting is not bad enough for the unions to deter a deviation, whereas it is bad enough under a strong policy. 5. Is strong policy credible? We now depart from the assumption that Government policy is exogenous. From Proposition 1 we know that cooperation is never sustainable if of government policy. 6, < Ss, and always sustainable if S,>SA, irrespective We shall focus on the more interesting intermediate case, where S’<S, <SA. That is, cooperation is sustainable only if the Government is expected to follow a strong policy. Clearly, as the Government benefits from cooperation, it will be tempted to announce that it will pursue a strong policy if cooperation breaks down. We shall look at whether such an announcement is credible, that is, whether strong policy is time-consistent. S. Holden, Exchange rate policy and wage formation 1553 This problem is somewhat more complicated to analyse than a standard repeated game problem. As long as the unions cooperate, full employment and zero inflation are achieved simultaneously. Thus, accommodating and strong policies coincide, so there is no policy choice for the Government. Yet whether or not cooperation is sustainable depends on the policy the Government will follow if cooperation breaks down. If there is no agreement on wage moderation (because the agreement has broken down), the per period payoff of the Government is higher if it follows an accommodating policy. Furthermore, the Government has no hope that the present leaderships in the unions will restart cooperation. Yet the Government will also be interested in what the new leaderships of the unions It seems intuitive that the Government will do if there is a replacement2 can ‘encourage’ the new leaderships of the unions to reach an agreement on wage restraint by following a strong policy before there is a replacement. Correspondingly, if the Government follows an accommodating policy, then it seems reasonable that this might lead to independent wage setting also for new leaderships of the unions. This intuition is formalised in the following strategies and Proposition: Government (1) Follow a strong policy if the Government has followed a strong policy until now. (2) If the Government has ever followed an accommodating policy, then follow an accommodating policy. Unions (1) Cooperate if the Government has followed a strong policy until now, and if no single union (with the present leadership) has ever deviated from cooperation. (2) Do not cooperate if the Government has ever followed an accommodating policy or if some union alone (with the present leadership) has ever deviated from cooperation. Proposition 2. Let ~3~~6~~6~. For all pUe(O, l), there exists a critical value 6* ~(0,l) such that cooperation is sustainable as a subgame perfect equilibrium if and only if 6,26*. Furthermore, 6* is increasing in po, so that the smaller ‘Assuming that the leaderships of all the unions are replaced at the same time is of course unrealistic. A more realistic interpretation of this feature is that an exogenous event takes place which makes all unions reconsider any agreement on wage moderation. Examples of such events can be an adverse supply shock to the economy or that ‘many’ of the leaderships of the unions are replaced. 1554 S. Holden, Exchange rate policy and wage formation the probability that the leaderships of the unions are replaced, ‘patience’ is required of the Government. Proof: the more See appendix. The intuition here is that a patient Government will be willing to follow a strong policy if the agreement breaks down, because a patient Government puts sufficient weight on the expected future gain of inducing new leaderships of the unions to reach an agreement on wage restraint. The existing leaderships of the unions will realise this, thus, a patient Government will be able to achieve both full employment and zero inflation in situations where a less patient Government will achieve neither. Trigger strategy equilibria have been criticised on the grounds that they are not ‘renegotiation proof’, i.e. if a deviation were to occur, the unions would have an incentive to agree on not undertaking the punishment. This argument seems compelling in an analysis of a game between perfectly rational players. Yet renegotiation proofness is not necessarily an appropriate requirement concerning models of union behaviour. It would be very hard for the leadership of a union to suggest wage moderation if another union defected the previous year. Arguments like ‘Last year was a mistake, but they promised that this year...’ may have trouble in convincing the union membership. Thus, a deviator cannot be certain that a deviation will be ‘forgotten’. I find it more realistic to assume that whether or not it is possible to restart an agreement is determined by other aspects, rather than being inferred directly from assumptions concerning union behaviour. The best would be to have an explicit model for these other aspects, but in the absence of this, I let this be determined by an exogenous random variable. 6. Concluding remarks I have analysed the interaction between wage formation and exchange rate determination in an economy with many trade unions. It is shown that such an economy can exhibit some of the same features as Horn and Persson (1988) argue hold in an economy with a single central trade union, as accommodating exchange rate policy may lead to both high inflation and high unemployment. The intuition behind the results is different, however. Horn and Persson’s result arises as the central trade union sets a high nominal wage in anticipation of a devaluation, thus obtaining its target real wage. In my model the trade unions have a comon interest in achieving full employment, yet this may not be possible to realise because each union will have an incentive to deviate from any agreement. An accommodating exchange rate policy will reduce the costs to the unions of a breakdown of S. Holden, Exchange rate policy and wage formation 1555 an agreement, and this may make cooperation less likely, as the punishment for a defection from the agreement wll be less severe. In my model, as well as Horn and Persson’s, a short-sighted government will find it difficult to make a non-accommodating policy credible, as the government is assumed to make a short-term gain from breaking its Thus both Horn and Persson (1988) and this paper provide promises. arguments for the use of external constraints on government policy. In fact, in Britain and Norway advocates of joining the European Monetary System often use the argument that this would make a non-devaluation policy credible [see e.g. the Economist (1989)]. Furthermore, within these models one can also argue, as do Fischer and Summers (1989) that governments should not make any attempts to reduce the costs of inflation, as this may reduce credibility. But one should be aware that any of these conclusions depend crucially on the assumption that anti-inflationary policy is indeed enough to remove inflation without large reductions in output. Empirical evidence on these matters is as yet scarce [cf. Blackburn and Christensen (1989)] so more research, both theoretical and empirical, seems necessary before firm policy conclusions can be drawn. Appendix Proof of Proposition 1. The existence of a critical value is a general property of trigger strategies in repeated games, so no proof is provided for this. Observe that it is not possible for the unions to inflict a harsher punishment on a deviator than what is the case with the strategy above, as a single union can always achieve Wt or Wf (depending on Government policy) through industry bargaining, and the other unions cannot get more. Thus, the strategy above constitutes an optimal penal code, implying that if cooperation is not sustainable with this punishment, then no other punishment will do [cf. Abreu (1988)]. To see that 6*> as, note that VA> Us, so equality in (17) and (18) gives 6* > 6’. 0 Proof of Proposition 2. It follows from Proposition 1 that the strategy of the unions is a best reply in every possible subgame, and that it inflicts the harshest possible punishment on any deviator. As I have neglected revaluations, following a strong policy is also the harshest punishment the Government can inflict on a deviating union. It remains to show that the Government strategy is a best reply in every possible subgame. If cooperation breaks down and the Government follows an accommodating policy, then a new agreement will never be formed with this Government, resulting in W: and accommodating policy in all future periods. Let GoA denote the per period payoff of the Government in this case (total expected payoff is GoA/( 1 - 6,)). E.E.R.- C S. Holden, Exchange rate policy and wage formation 1556 If cooperation breaks down and the Government instead follows a strong policy, the old leaderships of the unions will set Wf. However, in each period there is a probability 1 -pv that the leaderships are replaced, and in this case the new leaderships will form an agreement. Denote Go’ and GS the per period payoff of the Government with the old leaderships (without cooperation) and the new leaderships (with cooperation), respectively. The total expected payoff of the Government is Go’ + pu~GGos + p:G;GoS +. . . + (1 - pu)G,GS +(l -p;)G;GS+(l = Gas/( 1- The Government pu&J -p;)S;G’+... + &A will choose GoA5 Go?1- 6,)/( 1- 1- p,)@IC( a strong ~“6,) I- 6,)( 1 -p&)1. policy if + a,( 1 -pu)Gs/( 1 -pa&J. (A.1) We have GoS< GoA < GS, and note that the right hand side on (A.l) is a weighted average of Go’ and GS. For any given p”~(0, l), the weight on GS is one when 6, approaches one and strictly increasing in 6,, approaching approaching zero when 6, approaches zero. Thus equality in (A.l) defines a critical value 6* such that (A.l) will hold if and only if 6,26*. 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