Functional Concepts in Mental Retardation: Finding the Natural Essence of an Artificial Category

Abstract

Although there have always been people considered to have mental retardation (MR), the category has proven surprisingly difficult to define adequately. This is because it includes a subcategory of mild MR whose members are part of a larger population of marginally competent people, some of whom may be considered to have other forms of disability or who do not qualify as disabled. Where does one draw the line between those incompetent or marginal people who have MR and those who do not? IQ scores have proven inadequate both because they do not capture the full range of ways of being unintelligent and because of the arbitrariness of any particular cutting score. Measures of adaptive behavior have been inadequate because they are not sufficiently grounded in a theory of multiple intelligences, and, thus, they confound MR with other forms of disability. Although MR is a disability status, and thus is somewhat of an artificial social invention, the key to devising a valid definition of mild MR is to ground it in its natural taxon, as determined from the behaviors of people widely viewed as having MR. In exploring the various functional concepts embedded within the formal definitions of MR, the key to the natural category of MR is an inability to protect oneself, without supports, against potential catastrophic failure in academic, daily living, and social roles. Particular emphasis is placed on gullibility and other forms of social vulnerability as a central aspect of MR's natural taxon.