 Three leading defenses against this criticism have been offered. Some virtue ethicists (Kupperman 2009) have conceded that virtue is extremely rare, but argued that it may still be a useful regulative ideal. Others (Hurka 2006; Merritt 2000) have attempted to weaken the concept of virtue in such a way as to enable more people, or at least more behaviors, to count as virtuous. Still others (Kamtekar 2004; Russell 2009; Snow 2010; Sreenivasan 2002) have challenged the situationist evidence or its interpretation. While it remains unclear whether these defenses succeed, grappling with the situationist challenge has led both defenders and challengers of virtue ethics to develop more nuanced and empirically informed  views.[10]