Nathan Ballantyne

David Lewis and Peter van Inwagen have claimed that there are no “knockdown” arguments in philosophy. Their claim appears to be at odds with common philosophical practice: philosophers often write as though their conclusions are established or proven and that the considerations offered for these conclusions are decisive. In this paper, I examine some questions raised by Lewis’s and van Inwagen’s contention. What are knockdown arguments? Are there any in philosophy? If not, why not? These questions concern the nature of the philosophical enterprise and our answers have implications for the limits on the attitudes of informed, rational thinkers.

Recent work on the nature of luck widely endorses the thesis that an event is good or bad luck for an individual only if it is significant for that individual. In this paper, I explore this thesis, showing that it raises questions about interests, well-being, and the philosophical uses of luck. In Sect. 1, I examine several accounts of significance, due to Pritchard (2005), Coffman (2007), and Rescher (1995). Then in Sect. 2 I consider what some theorists want to ‘do’ with luck, taking important examples from epistemology (explaining Gettier-style examples) and political philosophy (offering a rationale for the just distribution of resources in society), while suggesting implications for significance. Drawing together lessons from Sects. 1 and 2, I develop a new account of significance in Sect. 3 before concluding with reflections on the debate in Sect. 4.