The weight of fairness

Many philosophers argue that individuals have duties to do their fair shares of the demands of achieving important common ends. But what happens when some individuals fail to do their fair shares? Are the remaining duty bearers required to take up the slack? The most prominent view, Fair Shares, holds that individuals are never required to take up the slack. But this view has counterintuitive implications; in many cases, it would show callous disregard not to take up the slack to help those in dire need. The central alternative, Slack-Taking, holds that considerations of fairness have no bearing in determining whether individuals are required to take up the slack. But this view fails to capture the practical importance of fairness in nonideal circumstances. I defend an alternative view, Weighing, according to which individuals properly weigh the value of fairness against the value of taking up the slack in determining whether they are all-things-considered required to take up the slack. While this view has been suggested before in the literature, I develop it by clarifying its structure and underlying rationale and defending it against important recent objections.