History of Learning Disabilities: Hinshelwood's
Logical Flaw

James Hinshelwood, a Glasgow eye surgeon, is today cited as the first major figure in what became the field of learning disabilities. There is, however, a logical flaw inherent in Hinshelwood's reasoning.

In 1907, a schoolmaster in Glasgow, Scotland, mentioned to a county Medical Officer of Health that he was "greatly puzzled" about four of his students. They were the youngest brothers in a family of eleven children and, unlike their seven siblings, had "experienced the greatest difficulties in learning to read." The medical officer, a former student of James Hinshelwood, "at once recognized" the "true nature of the difficulty." He referred the boys to his former mentor to confirm the diagnosis and provide the schoolmaster with expert help.

Hinshelwood confirmed the medical officer's preliminary conclusions: the boys indeed had congenital word-blindness, a condition that "frequently assumes a family type," that probably was hereditary and that was caused by a defective language-related area of the brain. He reasoned that, because the reading problems were clustered in one family, and because the four boys had normal general intelligence, lacked visual problems, had good visual memory except for letters and words, had a family life which had not impeded their siblings' learning, but had failed to read with school instruction that had been successful with their siblings, it was "evident that their cerebral defect was a purely local one … that it was strictly confined to the cerebral area for the visual memory of words and letters, the left angular gyrus, and did not extend at all beyond that."¹

Hinshelwood concluded that the root of congenital word-blindness lay in children's brains because he had observed that dysfunctional reading symptoms found in adults with brain lesions were analogous to those of certain children with reading problems. If an inability to recognize and remember letters and words, or to unite recognizable letters into syllables or into words, was acquired word-blindness, a symptom of localized brain damage in adults, and if it was clear that sensory functioning, intellectual functioning and environmental conditions could be excluded as causes of the reading disability, and if the reading symptoms were similar to those of acquired word-blindness, it was "evident" — Hinshelwood's exact word — that the problem was caused by localized brain damage that was probably hereditary.²

This line of reasoning, however, comprises an invalid argument: If A then B; B; therefore A.

Hinshelwood's argument can be summarized as follows:

There may perhaps be some readers who are unable to see that the above argument is invalid. For their benefit, another argument, showing the same form as the above one is offered below. The invalidity of this argument, however, cannot be doubted.

Goodman used another analogy to point out the logical flaw inherent in Hinshelwood's reasoning: A drought can kill vegetation. If, however, we find dead vegetation, we cannot assume that drought was the cause. The vegetation could have been destroyed, not by drought but by any number of causes including nonbiological ones such as lumbering.³ Consider also that, when a person is being chased by a ferocious bull, he will run. However, when we see a person running, we cannot jump to the conclusion that he is being chased by a bull. Similarly, if a brain-damaged person exhibits certain characteristics, we cannot simply jump to the conclusion that a person is brain damaged when we see him exhibiting the same characteristics. There may be many other reasons for his behavior.

In his diagnosis of the four boys, Hinshelwood rejected or ignored the role that school, family, and other environmental conditions may have played. As Coles points out, there were other plausible explanations for the boys' reading difficulties. Perhaps by the time the eighth child arrived, the parents of this large mining family were too busy and too tired to provide the nurturing they had given the others. Perhaps a large family dependent upon a small salary had become increasingly poor as the family grew, and the diminishing financial means relative to family needs had adversely affected the younger children.⁴ Hinshelwood also ignored the role motivation might have played. Upon leaving school, the oldest of the four boys, motivated by his enthusiasm for football (soccer), managed to master on his own the vocabulary of football terms, and could read, "fairly well," the football reports of a sports newspaper that he religiously bought. Yet, the young man had great difficulty reading a child's first primer or an "ordinary book."⁵

Sources:

1. Hinshelwood, J., "Four cases of congenital word-blindness occurring in the same family," British Medical Journal, 1907, vol. 2, 1229-1232, cited in Coles, The Learning Mystique, 3-5.
2. Coles, The Learning Mystique, 5-6.
3. Goodman, J. F., "Organicity as a construct in psychological diagnosis," in T. R. Kratochwill (ed.), Advances in School Psychology (Hillsdale: Lawrence Erlbaum, 1983), 101-139.
4. Coles, The Learning Mystique, 4.
5. Hinshelwood, "Four cases of congenital word-blindness," cited in Coles, The Learning Mystique, 4.