long term competition in a dynamic game the cold fish war this article presents a model of credible voluntary collective agreements in a dynamic game these agreements are implicit in collections of history dependent threat strategies i consider the strategies in a game of resource exploitation credibility is represented by perfect equilibrium voluntarism requires at least that all behavior be supported by the threat of collapse of the agreement which would return the players to the memoryless equilibrium collective rationality requires that the agreement be robust to the possibility of mutually beneficial renegotiation i analyze the set of agreements meeting each of these restrictions

commodity price shocks and civil conflict evidence from colombia how do income shocks aect armed con ict theory suggests two op posite eects if labor is used to appropriate resources violently higher wages may lower con ict by reducing labor supplied to appropriation this is the opportunity cost eect alternatively a rise in contestable income may increase violence by raising gains from appropriation this is the rapacity eect our paper exploits exogenous price shocks in inter national commodity markets and a rich dataset on civil war in colombia to assess how dierent income shocks aect con ict we examine changes in the price of agricultural goods which are labor intensive and natural resources which are capital intensive we focus on coee and oil the two largest exports we nd that a sharp fall in coee prices in the 1990s increased violence dierentially in regions growing more coee by lower ing wages and the opportunity cost of joining armed groups in contrast a rise in oil prices increased violence dierentially in the oil region by in creasing municipal revenue siphoned through rapacity this pattern holds in several other agricultural and natural resource sectors providing robust evidence that price shocks aect con ict in opposite directions depending on the factor intensity of the commodity

the tragedy of the commons in a violent world earlier research has shown that the tragedy of the commons may be resolved by folk theorems for dynamic games in this article we graft on a standard natural resource exploitation game the possibility to appropriate the resource through violent means because conflict emerges endogenously as resources get depleted the threat supporting the cooperative outcome is no longer subgame perfect and thus credible the unique equilibrium is such that players exploit noncooperatively the resource when it is abundant and they revert to conflict when it becomes scarce the players utility is shown to be lower even if conflict wastes no resources

natural resources curse or blessing are natural resources a curse or a blessing the empirical evidence suggests that either outcome is possible this paper surveys a variety of hypotheses and supporting evidence for why some countries benefit and others lose from the presence of natural resources these include that a resource bonanza induces appreciation of the real exchange rate deindustrialization and bad growth prospects and that these adverse effects are more severe in volatile countries with bad institutions and lack of rule of law corruption presidential democracies and underdeveloped financial systems another hypothesis is that a resource boom reinforces rent grabbing and civil conflict especially if institutions are bad induces corruption especially in nondemocratic countries and keeps in place bad policies finally resource rich developing economies seem unable to successfully convert their depleting exhaustible resources into other productive assets the survey also offers some welfare based fiscal rules for harnessing resource windfalls in developed and developing economies

the armed peace a punctuated equilibrium theory of war according to a leading rationalist explanation war can break out when a large rapid shift of power renders unbelievable a rising state s promise to compensate its declin ing opponent causing the latter to attack preventively this mechanism does not provide a complete and coherent explanation of war because it does not specify how inefficient fighting resolves this commitment problem we present a complete information model of war as a sequence of battles and show that although opportunities for a negotiated settle ment arise throughout the very desirability of peace creates a commitment problem that undermines its likelihood because players have incentives to settle as soon as possible they cannot credibly threaten to fight long enough if an opponent launches a surprise at tack this decreases the expected duration and costs of war and causes mutual deterrence to fail fighting s sheer destruction improves the credibility of these threats by decreasing the benefits from continuing the war equilibrium fighting may involve escalating costs that exceed the value of the stakes by the time peace is negotiated and that leave both players worse off than when the war began

conflict and deterrence under strategic risk we examine the determinants of cooperation and the effectiveness of deterrence when fear is a motive for conflict we contrast results obtained in a complete information setting with those obtained in a setting with strategic risk where players have different information about their environment these two strategic settings allow us to identify and distinguish the role of predatory and preemptive incentives as determinants of cooperation and conflict in our model weapons unambiguously facilitate peace under complete information in contrast under strategic risk we show that increases in weapon stocks can have a nonmonotonic effect on the sustainability of cooperation we also show that under strategic risk asymmetry in military strength can facilitate peace and that anticipated peacekeeping interventions may improve incentives for peaceful behavior

can violence harm cooperation experimental evidence abstract in this paper we argue that natural resource conservation is jeopardised by the ability of users to resort to violence to appropriate resources when they become scarce we provide evidence from a lab experiment that participants interacting in a dynamic game of common pool resource extraction reduce their cooperation on efficient levels of resource extraction when given the possibility to appropriate the resource at some cost i e through conflict theoretically cooperation is achievable via the threat of punishment strategies which stop being subgame perfect in the presence of conflict accordingly we argue that the observed reduction of cooperation in the game s early stages in the lab is a consequence of participants correctly anticipating the use of appropriation when resources become scarce

arming as a strategic investment in a cooperative equilibrium to develop a positive economic theory of military spending this analysis focuses on a game theoretic general equilibrium model of international conflict in which consumption peaceful investment and military spending are endogenously determined the analysis illustrates that when there is repeated interaction between nations a game of threats and punishments generally will not support a disarmament outcome and that fluctuations in military spending can be an endogenous result of fluctuations in aggregate economic activity furthermore the analysis shows how the relation between aggregate economic activity and military spending qualitatively depends on whether governments are acting opportunistically or cooperatively copyright 1990 by american economic association

do trade costs in goods market lead to home bias in equities abstract two of the main puzzles in international economics are the consumption and the portfolio home biases we solve for international equity portfolios in a two country two good stochastic equilibrium model with trade costs in goods markets we show that introducing trade costs as suggested by obstfeld and rogoff obstfeld m rogoff k 2000a the six major puzzles in international macroeconomics is there a common cause nber macroeconomics annual 15 is not sufficient to explain these two puzzles simultaneously on the contrary we find that trade costs create a foreign bias in portfolios for reasonable parameter values this result is robust to the addition of non tradable goods for standard calibrations of the preferences

contesting resources rent seeking conflict and the natural resource curse a growing empirical literature links natural resource abundance and pointiness to impeded economic growth and civil strife we develop rent seeking and conflict models that capture the most salient features of contests for resource rents and show how both resource abundance and geographical clustering can be associated with intense contests and sub optimal economic performance however we also show that these relationships are not necessarily monotonous pointiness can trigger more intense contests but can also facilitate the coordination on peaceful outcomes finally we show that contesting resources through violent conflict may yield superior outcomes from an economy wide perspective than contests through rent seeking

international portfolios capital accumulation and foreign assets dynamics despite the liberalization of capital ows among oecd countries equity home bias remains sizable we depart from the two familiar explanations of equity home bias transaction costs that impede international diversi cation and terms of trade responses to supply shocks that provide risk sharing so that there is little incentive to hold diversi ed portfolios we show that the interaction of the following ingredients generates a realistic equity home bias capital accumulation shocks to the e ciency of physical investment as well as international trade in stocks and bonds in our model domestic stocks are used to hedge uctuations in local wage income terms of trade risk is hedged using bonds denominated in local goods and in foreign goods in contrast to related models the low level of international diversi cation does not depend on strongly countercyclical terms of trade the model also reproduces the cyclical dynamics of foreign asset positions and of international capital ows

a strategic analysis of global warming theory and some numbers we model the global warming process as a dynamic commons game in which the players are countries their actions at each date produce emissions of greenhouse gases and the state variable is the current stock of greenhouse gases the theoretical analysis is complemented by a calibration exercise the first set of results establishes theoretically and then with illustrative numbers the over emissions due to a tragedy of the commons the power of simple sanctions to lower emissions and increase welfare is then examined as is the effect of cost asymmetry finally a complete theoretical charactrization is provided for the best equilibrium and it is shown that it has a very simple structure it involves a constant emission rate through time

household location and race estimates of a multinomial logit model a multinomial logit model of household location choice in which families choose from a number of mutually exclusive residential location is estimated regression results indicate that the locational choices of white and black households are importantly but differently affected by their socioeconomic characteristics in that regard black suburbanization patterns are little influenced by large simulated changes in household characteristics findings suggest that policies which focus on the educational and earnings opportunities of blacks would likely be largely ineffectual in fostering the integration of predominantly white suburban communities copyright 1989 by mit press

cross border returns differentials were the u s to persistently earn substantially more on its foreign investments u s claims than foreigners earn on their u s investments u s liabilities the likelihood that the current environment of sizeable global imbalances will evolve in a benign manner increases however we find that the returns differential of u s claims over u s liabilities is far smaller than previously reported and importantly is near zero for portfolio equity and debt securities for portfolio securities we confirm our finding using a separate dataset on the actual foreign equity and bond portfolios of u s investors and the u s equity and bond portfolios of foreign investors in the context of equity and bond portfolios we find no evidence that the u s can count on earning more on its claims than it pays on its liabilities finally we reconcile our finding of a near zero returns differential with observed patterns of cumulated current account deficits the net international investment position and the net income balance jel codes f3

linking conflict to inequality and polarization in this paper we study a behavioral model of conflict that provides a basis for choosing certain indices of dispersion as indicators for conflict we show that a suitable monotone transform of the equilibrium level of conflict can be proxied by a linear function of the gini coefficient the herfindahl hirschman fractionalization index and a specific measure of polarization due to esteban and ray jel classification d74 d31

a dynamic theory of resource wars we develop a dynamic theory of resource wars and study the conditions under which such wars can be prevented our focus is on the interaction between the scarcity of resources and the incentives for war in the presence of limited commitment we show that a key parameter determining the incentives for war is the elasticity of demand our first result identifies a novel externality that can precipitate war price taking firms fail to internalize the impact of their extraction on military action in the case of inelastic resource demand war incentives increase over time and war may become inevitable our second result shows that in some situations regulation of prices and quantities by the resource rich country can prevent war and when this is the case there will also be slower resource extraction than the hotelling benchmark with inelastic demand our third result is that because of limited commitment and its implications for armament incentives regulation of prices and quantities might actually precipitate war even in some circumstances where wars would not have arisen under competitive markets copyright 2012 oxford university press

intra urban mobility migration and tenure choice this analysis develops a model in which for the first time households mobility decisions are separated into intra urban movements and migrations these two mobility decisions and the households tenure own rent choice are estimated as part of a multinomial logit framework and are found to be jointly determined the literature suggests that the intra urban mobility and migration decisions are motivated by quite different factors consequently by separating the two choices for the purpose of estimation each equation can be specified more correctly in addition variables which affect migration can be shown to have an impact on intra urban mobility and tenure choice which would otherwise be ignored copyright 1991 by mit press

institutions and the resource curse countries rich in natural resources constitute both growth losers and growth winners we claim that the main reason for these diverging experiences is differences in the quality of institutions more natural resources push aggregate income down when institutions are grabber friendly while more resources raise income when institutions are producer friendly we test this theory building on sachs and warner s influential works on the resource curse our main hypothesis that institutions are decisive for the resource curse is confirmed our results contrast the claims of sachs and warner that institutions do not play a role

delay in contests abstract why is there delay in contests in this paper we follow and extend the line of reasoning of carl von clausewitz to explain delay for a given contest technology delay may occur if there is an asymmetry between defense and attack if the expected change in relative strengths is moderate and if the additional cost of investment in future strength is low

the external wealth of nations measures of foreign assets and liabilities for industrial and developing countries abstract although capital flows are closely monitored surprisingly little is known about the accumulated stocks of foreign assets and liabilities held by various countries especially in the developing world this paper constructs estimates of foreign assets and liabilities and their equity and debt subcomponents for a sample of 67 industrial and developing countries it characterizes the stylized facts of international balance sheets and asks whether there are trends in net foreign asset positions and shifts in debt equity ratios over time finally it explores the sensitivity of estimated stock positions to the treatment of valuation effects not captured in balance of payments data

persistent fighting and shifting power three striking features about both interstate and civil war are 1 there are often periods of persistent fighting 2 fighting commonly ends in negotiated settlements as well as in militarily decisive outcomes and 3 fighting sometimes recurs this article links these features to shifts in the distribution of power and to the fact that one of the functions of fighting is to forestall adverse shifts the analysis centers on a simple model of state consolidation the equilibrium displays these features fighting occurs when the distribution of power is shifting rapidly the factions avoid fighting and cut deals when the distribution of power shifts slowly or is stable fighting resumes if the distribution of power again begins to shift rapidly the analysis also shows that state consolidation can occur without fighting if the process is sufficiently slow fighting now rather than later can also reduce the total cost of fighting

program participation and farm level adoption of conservation tillage estimates from a multinomial logit model over the past decade conservation compliance has reduced soil erosion what will happen to these erosion benefits if commodity programs are eliminated or if the subsidy level is greatly reduced this study investigates whether there will be a significant decline in the amount of acreage on which conservation practices are adopted if future farm program benefits are not tied to conservation compliance

country portfolios in open economy macro models this paper develops a simple approximation method for computing equilibrium portfolios in dynamic general equilibrium open economy macro models the method is widely applicable simple to implement and gives analytical solutions for equilibrium portfolio positions in any combination or types of asset it can be used in models with any number of assets whether markets are complete or incomplete and can be applied to stochastic dynamic general equilibrium models of any dimension so long as the model is amenable to a solution using standard approximation methods we first illustrate the approach using a simple two asset endowment economy model and then show how the results extend to the case of any number of assets and general economic structure

valuation effects and the dynamics of net external assets abstract valuation effects can imply that the traditional current account is an inaccurate measure of the change in the net foreign asset nfa position this paper uses new developments in the analysis of portfolio choice in general equilibrium to investigate valuation effects in a two country model broadly speaking the valuation effects in the model correspond to those observed in the data but there is a key distinction between unanticipated and anticipated valuation effects unanticipated effects can be large dominating the movement in nfa but anticipated effects arise only at higher orders of approximation and are small for reasonable parameterizations