 These recent developments have spawned a burgeoning literature, with a focus on the issue of normative powers themselves, e.g., Chang (2013, 2020), Westlund (2013, 2018), Nieswandt (2017), as well as their propriety for explaining promissory obligation, e.g., E. Taylor (2013), Fruh (2014, 2019), Molina (2019), Melenovsky (2017) and others.