David Hume's sympathetic principle applies to physical equals. In his account, we sympathize with those like us. By contrast, Adam Smith's sympathetic principle induces equality. We consider Hume's “other rational species” problem to see whether Smith's wider sympathetic principle would alter Hume's conclusion that “superior” beings will enslave “inferior” beings. We show that Smith introduces the notion of “generosity,” which functions as if it were Hume's justice even when there is no possibility of contract.