Review of Economic Dynamics · 2025 · Sebastian Graves、Victoria Gregory、Lars Ljungqvist、Thomas J. Sargent
中文摘要
Heckman 等 (1998a)(HLT)的模型包含信贷市场与期内劳动供给不可分性,这两者正是 Ljungqvist 与 Sargent (2006) "时间平均化"模型的核心特征。但该模型假定在强制退休年龄之前劳动供给无弹性,从而关闭了时间平均化。我们通过将退休年龄内生化来激活时间平均化。我们加入的基准社会保障制度使所有工人的退休决策都落在角点解上,从而使我们的模型能够复现 HLT 模型中的大多数结果。社会保障与税收改革将工人从这些角点上移开,提高了总劳动供给弹性,并可能引致"双重劳动力市场"。HLT 的 Ben-Porath 人力资本技术为受过大学教育的工人生成更陡峭的收入轨迹,在我们的模型中,这使其劳动供给对税收与社会保障改革的抵御能力强于高中工人的劳动供给。但 Ben-Porath 技术固有的非凸性可能带来"临界点":在临界点处,增税会使那些在较低税率下原本选择长职业生涯并进行大量人力资本投资的工人,离散地跳跃到选择短得多的职业生涯、并进行少得多的在职人力资本积累。
Abstract
The Heckman et al. (1998a) (HLT) model includes credit markets and within-period labor supply indivisibilities, two essential features of Ljungqvist and Sargent (2006) “time-averaging” models. But by assuming inelastic labor supplies until a mandatory retirement age, it shuts down time-averaging. We activate time-averaging by endogenizing retirement ages. Our addition of a baseline social security system puts all workers at corner solutions of their retirement decisions, letting our model reproduce most outcomes in HLT's model. By dislodging workers from those corners, social security and tax reforms raise the aggregate labor supply elasticity and can bring about a “dual labor market.” HLT's Ben-Porath human capital technologies generate steeper earnings profiles for college-educated workers that in our model make their labor supplies more resilient to tax and social security reforms than high school workers' labor supplies. But nonconvexities inherent in the Ben-Porath technologies can bring “tipping points” at which tax increases cause workers who at lower tax rates had chosen long careers and made substantial human capital investments to jump discretely to choosing much shorter careers and doing much less on-the-job human capital accumulation.