SLD Parameters
A definition delineates the nature and limits of a phenomenon (Kavale, Forness, & Lorsbach, 1991). The SLD definition does not adequately circumscribe the condition, meaning that its interpretation for practical purposes (i.e., operationalization) is suspect. For example, "discrepancy" is not specifically articulated in the SLD definition but has been the primary criterion used for SLD identification. The disconnect between the formal definition and its operational consequences demonstrates the impossibility of the theoretical being accurately represented in the operational and vice versa. Discrepancy alone is too disconnected from what it actually stipulated in the formal definition to meet the criteria of significance and meaningfulness necessary for a valid operational definition. It is important to emphasize that "specific learning disability" is the concept articulated in the formal definition. As a category of special education defined in the law, SLD should represent a particular and circumscribed disability class (Kavale & Forness, 1985a). For linguistic reasons, however, it has been easier to use the plural term "learning disabilities" which has eroded the notion of SLD as a discrete and independent condition different from other more generalized learning deficiencies. Predictably, the meaning of SLD is diluted by the conventional wisdom suggesting that "there are many types of learning disability" thereby extending the boundary conditions to the point where SLD is no longer a distinct classification. Thus, in practical terms, SLD moves in a direction that makes it increasingly unrecognizable (Kavale & Forness, 2003). The logical relation moves from All students with SLD have learning problems to All students with learning problems have SLD which is not true if SLD is properly viewed as a categorical designation (Kavale & Forness, 1985b). No other category in special education has demonstrated similar confounding which has resulted in the very existence of SLD being called into question by being termed "myth" (McKnight, 1982), "questionable construct" (Klatt, 1991), or "imaginary disease" (Finlan, 1993). Clearly, SLD should reclaim its position as a legitimate category for students experiencing particular types of learning difficulties. A good place to start is with a new formal definition that articulates strict parameters for the condition. Simple tinkering with a new operational definition cannot achieve this goal.
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