Econ Papers Daily / 期刊论文
评让·梯若尔《资产泡沫与世代交叠》
Comment on ‘Asset Bubbles and Overlapping Generations’ by Jean Tirole
摘要
Tirole (1985) studied an overlapping generations model with capital accumulation and showed that the emergence of asset bubbles solves the capital over‐accumulation problem. His Proposition 1(c) claims that if the dividend growth rate is above the bubbleless interest rate (the steady‐state interest rate in the economy without the asset) but below the population growth rate, then bubbles are necessary in the sense that there exists no bubbleless equilibrium but there exists a unique bubbly equilibrium. We show that this result (as stated) is incorrect by presenting an example economy that satisfies all assumptions of Proposition 1(c) but its unique equilibrium is bubbleless. We also restore Proposition 1(c) under the additional assumptions that initial capital is sufficiently large and dividends are sufficiently small. We show through examples that these conditions are essential.
中文摘要
Tirole（1985）研究了一个包含资本积累的代际交叠模型，并指出资产泡沫的出现解决了资本过度积累问题。其命题1(c)声称，若股息增长率高于无泡沫利率（即无资产经济中的稳态利率）但低于人口增长率，则泡沫是必要的，即不存在无泡沫均衡，但存在唯一的有泡沫均衡。我们通过构造一个满足命题1(c)所有假设但唯一均衡为无泡沫的示例经济体，证明了该结果（如所述）是不正确的。我们还在额外假设初始资本足够大且股息足够小的条件下，恢复了命题1(c)。我们通过示例表明，这些条件是必不可少的。