标题： 凯恩斯跨期综合（KIS）模型：迈向统一且实证基础的财政政策框架 显示英文标题

标题： A Keynesian Intertemporal Synthesis (KIS) Model: Towards a unified and empirically grounded framework for fiscal policy

摘要： 本文开发了凯恩斯跨期综合（KIS）模型的新一代，这是一个宏观经济框架，旨在调和后凯恩斯主义（PK）和新凯恩斯主义（NK）传统的实证优势。这项工作的核心创新是摒弃传统的柯布-道格拉斯生产函数，转而采用替代弹性恒定（CES）的设定。这一修改直接源于Gechert等人（2021年）进行的元分析中的有力证据，该证据明确拒绝了资本与劳动之间替代弹性为1的假设。我们将这一发现与一系列关于财政乘数状态依赖异质性的元分析结论相结合（Gechert和Rannenberg，2018年），公共资本的生产率（Bom和Ligthart，2014年），支出工具的有效性层次（Gechert，2015年），以及里卡德等价理论的实证失败（Stanley，1998年）。由此产生的KIS-CES模型，在基于跨期优化的基础上，结合了家庭异质性、重视财富并惩罚债务的非标准偏好，以及受零下限约束的货币政策。数学推导表明，校准到一个经验上合理的值$\sigma < 1$的替代弹性成为调节收入分配并放大公共投资挤入效应的关键参数。该模型生成了一个内生的边际消费倾向，一个在危机中急剧增加的非线性财政乘数，以及一个结构上高于消费的公共投资乘数，从而提供了一个统一、严格且最重要的是经验上受约束的理论框架。 显示英文摘要

摘要： This paper develops a new generation of the Keynesian Intertemporal Synthesis (KIS) Model, a macroeconomic framework designed to reconcile the empirical strengths of the Post-Keynesian (PK) and New Keynesian (NK) traditions. The central innovation of this work is the abandonment of the traditional Cobb-Douglas production function in favor of a Constant Elasticity of Substitution (CES) specification. This modification is directly motivated by the compelling evidence from the meta-analysis by Gechert et al. (2021), which emphatically rejects the hypothesis of a unit elasticity of substitution between capital and labor. We integrate this finding with the conclusions from a wide range of meta-analyses on the state-dependent heterogeneity of fiscal multipliers (Gechert and Rannenberg, 2018), the productivity of public capital (Bom and Ligthart, 2014), the effectiveness hierarchy of spending instruments (Gechert, 2015), and the empirical failure of Ricardian Equivalence (Stanley, 1998). The resulting KIS-CES model, while based on intertemporal optimization, incorporates household heterogeneity, non-standard preferences that value wealth and penalize debt, and a monetary policy constrained by the zero lower bound. The mathematical derivations reveal that the elasticity of substitution, calibrated to an empirically plausible value of $\sigma < 1$, becomes a key parameter that modulates income distribution and magnifies the crowding-in effect of public investment. The model generates an endogenous MPC, a nonlinear fiscal multiplier that increases dramatically in crises, and a multiplier for public investment that is structurally higher than that for consumption, thus offering a unified, rigorous, and, above all, empirically disciplined theoretical framework.