This fascinating question takes center stage in Tyler Cowen’s beautiful new book Stubborn Attachments (pictured below). Professor Cowen, a polymath who teaches economics at George Mason University, combines a branch of moral philosophy called “population ethics” (pioneered by the late Derek Parfit) with a branch of social science called “welfare economics.” In summary, economists engaged in welfare economics attempt to measure the aggregate well-being of populations, while philosophers engaged in population ethics attempt to answer the question posed in the title of this post. Cowen’s contribution is to explore this question from an economic perspective. Furthermore, according to Cowen (spoiler alert!), the welfare of future generations should matter just as much as our own welfare. Or stated in the formal jargon of academic economics, we should apply a low “discount rate” (possibly even as low as zero; see Cowen, p. 127) to the future. (As Cowen notes on page 65 of his book, “A discount rate tells us how to compare future benefits to current benefits (or costs) when we make decisions.”) Although a zero-discount rate may look like a morally attractive principle at first glance, there are numerous practical and theoretical problems with this view. (See this overview, for example, or see this lecture by Jens Saugstad.) We will explore some of these difficulties in our next few posts.
prior probability 