Abstract The role of public banks in financing necessary investment is discussed with reference to a causal framework linking public and private expenditure in sequential time. The text starts by looking at lending to the public and private sector in Europe and develops a simple interpretation of it, which is used to discuss the causes of the recent financial crisis. The evidence shows that the recent financial crisis cannot be imputed to excessive public debt but possibly only to the fast accumulation of private debt. These facts can be interpreted in terms of a simple causality structure where public expenditure determines the level of economic activity. If causality can run from public to private expenditure, the role of public banks in the creation of new savings becomes potentially important because, being part of the public sector, they can play also an indirect role as monetary financial intermediaries, in addition to their traditional role as nonmonetary financial intermediaries recycling savings already accumulated in the past. The article discusses these two possible roles of public banks with reference to some examples. The case of investment for climate change mitigation shows that both roles are important for the pursuit of public policy goals. If only the traditional nonmonetary intermediary role is retained, in the absence of other incentives, the level of environmental investment risks being limited to that portion of the necessary investment that the market considers profitable, i.e., it would probably be insufficient to reduce the climate change risks. In the best variant, these necessary environmental investments would be realized at the expense of other necessary public investment. If, on the contrary, environmental investment is to be realized without reducing other necessary public investments, public banks should engage also in monetary financial intermediary’s activities aimed at creating new wealth. The text concludes by describing briefly the main logical consequences of the analysis developed.

中文翻译：

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必要的公共投资：公共银行的作用

摘要 参考将公共支出和私人支出按顺序时间联系起来的因果框架，讨论了公共银行在为必要投资融资方面的作用。文本首先考察了对欧洲公共和私营部门的贷款，并对其进行了简单的解释，用于讨论最近金融危机的原因。证据表明，最近的金融危机不能归咎于过度的公共债务，而只能归咎于私人债务的快速积累。这些事实可以用一个简单的因果关系结构来解释，其中公共支出决定了经济活动的水平。如果因果关系可以从公共支出延伸到私人支出，那么公共银行在创造新储蓄方面的作用可能变得很重要，因为作为公共部门的一部分，除了作为非货币金融中介回收过去积累的储蓄的传统角色外，它们还可以作为货币金融中介发挥间接作用。本文通过一些例子讨论了公共银行可能扮演的这两种角色。减缓气候变化投资的案例表明，这两种角色对于追求公共政策目标都很重要。如果只保留传统的非货币中介角色，在没有其他激励措施的情况下，环境投资风险水平仅限于市场认为有利可图的必要投资部分，即可能不足以减少气候变化风险。在最好的变体中，这些必要的环境投资将以牺牲其他必要的公共投资为代价。相反，如果要在不减少其他必要的公共投资的情况下实现环境投资，公共银行也应该从事旨在创造新财富的货币金融中介活动。正文最后简要描述了分析的主要逻辑结果。