Rational bubbles and macroeconomic fluctuations: The (de-)stabilizing role of monetary policyJournal articleLise Clain-Chamosset-Yvrard and Thomas Seegmuller, Mathematical Social Sciences, Volume 75, Issue C, pp. 1-15, 2015

We are interested in the existence of expectation-driven fluctuations of a rational bubble and the (de-)stabilizing role of monetary policy. This paper highlights the key role of credit market imperfections at the household level to explain bubble fluctuations and exhibits the stabilizing power of monetary rules responding to asset prices. We consider an overlapping generations exchange economy where households realize a portfolio choice between money and a bubble. Money is held because of a partial cash-in-advance constraint affected by the size of the bubble. A higher value of the bubble reduces the need of cash, and thus increases the fraction of consumption purchased on credit. Under these credit market features, multiplicity of steady-states (global indeterminacy) and expectation-driven fluctuations (local indeterminacy) can occur for arbitrarily small market distortions. Investing the stabilizing role of monetary policy, we show that when the monetary policy rule responds only to expected inflation, a more active rule can be destabilizing by promoting local indeterminacy and has no impact on the multiplicity of steady states. In contrast to the previous policy, when the rule responds also to asset prices, then the monetary policy can be stabilizing and rule out the multiplicity of steady states.

Fiscal policy, debt constraint and expectations-driven volatilityJournal articleKazuo Nishimura, Thomas Seegmuller and Alain Venditti, Journal of Mathematical Economics, Volume 61, Issue C, pp. 305-316, 2015

Imposing some constraints on public debt is often justified regarding sustainability and stability issues. This is especially the case when the ratio of public debt over GDP is restricted to be constant. Using a Ramsey model, we show that such a constraint can however be a fundamental source of indeterminacy, and therefore, of expectations-driven fluctuations. Indeed, through the intertemporal budget constraint of the government, income taxation negatively depends on future debt, i.e. on the expected level of production. This mechanism ensures that expectations on the future tax rate may be self-fulfilling. We show that this is promoted by a larger ratio of debt over GDP.

Market distortions and local indeterminacy: A general approachJournal articleTeresa Lloyd-Braga, Leonor Modesto and Thomas Seegmuller, Journal of Economic Theory, Volume 151, Issue C, pp. 216-247, 2014

We provide a methodology to study the role of market distortions on the emergence of indeterminacy and bifurcations. It consists in introducing general specifications for the elasticities of the crucial functions defining the aggregate equilibrium dynamics of the model. This allows us to study how market distortions influence the range of values for the elasticity of input substitution under which local indeterminacy and bifurcations occur, highlighting the main channels and classes of distortions responsible for indeterminacy. Most of the specific market imperfections considered in the related literature are particular cases of our framework. Comparing them we obtain several equivalence results in terms of local dynamic properties. Applying this methodology to the Woodford [30] framework we find that distortions in the capital market, per se, do not play a major role. We further show that, for empirically plausible values of elasticity of substitution between inputs, indeterminacy requires a minimal degree of distortions. This degree seems to be high under output market distortions, while with labor market distortions the required degree is empirically plausible.

Environmental Quality, Public Debt and Economic DevelopmentJournal articleMouez Fodha and Thomas Seegmuller, Environmental & Resource Economics, Volume 57, Issue 4, pp. 487-504, 2014

This article analyzes the consequences on capital accumulation and environmental quality of environmental policies financed by public debt. A public sector of pollution abatement is financed by a tax or by public debt. We show that if the initial capital stock is high enough, the economy monotonically converges to a long-run steady state. On the contrary, when the initial capital stock is low, the economy is relegated to an environmental poverty trap. We also explore the implications of public policies on the trap and on the long-run stable steady state. In particular, we find that government should decrease debt and increase pollution abatement to promote capital accumulation and environmental quality at the stable long-run steady state. Finally, a welfare analysis shows that there exists a level of public debt that allows a long run steady state to be optimal. Copyright Springer Science+Business Media Dordrecht 2014

Population growth in polluting industrializationJournal articleKarine Constant, Carine Nourry and Thomas Seegmuller, Resource and Energy Economics, Volume 36, Issue 1, pp. 229-247, 2014

Recently, many contributions have focused on the relationship between capital level, growth and population dynamics, introducing fertility choice in macro-dynamic models. In this paper, we go one step further highlighting also the link with pollution. We develop a simple overlapping generations model with paternalistic altruism according to wealth and environmental concerns. One can therefore explain a simultaneous increase in capital intensity, population growth and pollution, namely a polluting industrialization. We show in addition that a permanent productivity shock, possibly associated to technological innovations, promotes such a polluting development process, escaping a trap where the economy is relegated to low levels of capital intensity, population growth and pollution.

Longevity, pollution and growthJournal articleNatacha Raffin and Thomas Seegmuller, Mathematical Social Sciences, Volume 69, Issue C, pp. 22-33, 2014

We analyze the interplay between longevity, pollution and growth. We develop an OLG model where longevity, pollution and growth are endogenous. The authorities may provide two types of public services, public health and environmental maintenance, that participate to extend agents' life expectancy and to sustain growth in the long term. We show that global dynamics might be featured by a high growth rate equilibrium, associated with longer life expectancy and an environmental poverty trap. We examine changes in public policies: increasing public intervention on health or environmental maintenance display opposite effects on global dynamics, i.e. on the size of the trap and on the level of the stable balanced growth path. On the contrary, each type of public policy induces a negative leverage on the long-run rate of growth.

Aggregate instability under balanced-budget consumption taxes: A re-examinationJournal articleCarine Nourry, Thomas Seegmuller and Alain Venditti, Journal of Economic Theory, Volume 148, Issue 5, pp. 1977-2006, 2013

We re-examine the destabilizing role of balanced-budget fiscal policy rules based on consumption taxation. Using a one-sector model with infinitely-lived households, we consider a specification of preferences derived from Jaimovich (2008) [14] and Jaimovich and Rebelo (2009) [15] which is flexible enough to encompass varying degrees of income effect. When the income effect is not too large, we show that there exists a Laffer curve, which explains the multiplicity of steady states, and that non-linear consumption taxation may destabilize the economy, promoting expectation-driven fluctuations, if the elasticity of intertemporal substitution in consumption is sufficiently larger than one and the tax rate is counter-cyclical with respect to consumption. Numerical illustrations also show that consumption taxation may be a source of instability for most OECD countries for a wide range of structural parametersʼ configurations. We finally prove the robustness of our conclusions if we consider a discrete-time setup.

Destabilizing balanced-budget consumption taxes in multi-sector economiesJournal articleKazuo Nishimura, Carine Nourry, Thomas Seegmuller and Alain Venditti, International Journal of Economic Theory, Volume 9, Issue 1, pp. 113-130, 2013

We examine the impact of balanced-budget consumption taxes on the existence of expectations-driven business cycles in two-sector economies with infinitely-lived households. We prove that, whatever the relative capital intensity difference across sectors, aggregate instability can occur if the consumption tax rate is not too low. Moreover, we show through a numerical exercise based on empirically plausible tax rates that endogenous business-cycle fluctuations may be a source of instability for all OECD countries, including the US.

Rational bubbles and expectation-driven fluctuationsJournal articleStefano Bosi and Thomas Seegmuller, International Journal of Economic Theory, Volume 9, Issue 1, pp. 69-83, 2013

No abstract is available for this item.

A Note On Environmental Policy And Public Debt StabilizationJournal articleMouez Fodha and Thomas Seegmuller, Macroeconomic Dynamics, Volume 16, Issue 03, pp. 477-492, 2012

No abstract is available for this item.