 While some argue that the normative profile of understanding is essentially the same as the normative profile of knowledge (Grimm 2006; Khalifa 2013, 2017b; Greco 2014), others claim that they differ in important ways, and especially with respect to the way in which understanding, but not knowledge, seems compatible with luck. Among theorists who see a difference between knowledge and understanding here, we can distinguish those who claim that understanding can be fully externally lucky from those who think it can only be partly externally lucky.