... For example, Knetsch and Sinden (1984) speculated that the endowment effect would generalize broadly, despite using a model that did not permit generalization beyond students at the University of New England trading lottery tickets for $3 in the year 1984. Later research iteratively modified this generalization scope, showing that the endowment effect extends across goods (e.g., Rowe, D'Arge, & Brookshire, 1980;van Dijk & van Knippenberg, 1998), age groups (Harbaugh, Krause, & Vesterlund, 2001), cultures (Maddux et al., 2010), and species (Lakshminaryanan, Keith Chen, & Santos, 2008), but is limited by market features (Kahneman, Knetsch, & Thaler, 1990), learning (Apicella, Azevedo, Christakis, & Fowler, 2014Coursey, Hovis, & Schulze, 1987), and expertise (List, 2003). At the risk of overgeneralizing from a single example, this shows that the familiar, messy process of iterative science is in some cases capable of untangling the causal structure of social phenomena. ...