  Part of what concerns disability rights advocates is the questionable relation between the existence of certain impairments or bodily anomalies and the availability of equality of opportunity or well-being (Silvers, Wasserman, and Mahowald 1998; Amundson 2005; Asch and Wasserman 2005) that seems to be a common presumption in liberal eugenics theories. Broadly, they worry that many of these theorists are relatively uninformed about the life experiences of people with disabilities, or unfairly dismissive of their claims (Amundson 2005; Goering 2008), and thus rely on an overly negative evaluation of their quality of life. As such, efforts to promote “good birth” often undervalue existing people with disabilities. Additionally, advocates of liberal eugenics, it is argued, allow one trait to stand in for all of what a potential person can be (Asch and Wasserman 2005), and underestimate the value of human diversity that includes non-standard modes of human functioning linked to disability (Silvers 1998; Garland-Thomson 2012), and the possibility of “gains” made possible through living with disability (Baumrin and Murray 2014). (For more discussion, see entries on   disability: definitions and models;   and   feminist perspectives on disability.)