Abstract

Here's one piece of practical reasoning: "If I do this then a person will reap some benefits and suffer some costs. On balance, the benefits outweigh the costs. So I ought to do it." Here's another: "If I do this then one person will reap some benefits and another will suffer some costs. On balance, the benefits to the one person outweigh the costs to the other. So I ought to do it." Many influential philosophers say that there is something dubious about the second piece of reasoning. They say that it makes sense to trade-off costs and benefits within lives, but not across lives. In this paper I make a case for the second piece of reasoning. My case turns on the existence of morphing sequences—sequences of possible states of affairs across which people transform smoothly into other people