Molyneux’s Problem

The case of a flagpole that casts a shadow on the ground, which I discussed last week, is an instance of how counterexamples can undermine theories. However, this counterexample was theoretical in the sense that one didn’t need actually put a flagpole somewhere and make observations. Often a theoretical case will not do and we need a real experiment for solving a philosophical issue. In this way one of the most intriguing questions in modern philosophy has been answered: the Molyneux question.

In 1688 the scientist and politician William Molyneux sent a letter to John Locke in which he presented him with the following question, quoted by Locke in his An Essay Concerning Human Understanding (Book II, ch. ix, §8):

“Suppose a man born blind, now adult, who has learned how to distinguish by touch between a cube and a sphere of the same metal and about the same size, so that he can tell when he handles them which is the cube and which the sphere. Now suppose the cube and sphere to be placed on a table, and the blind man be made to see. Can he by his sight, before touching them, tell which is the globe, which the cube?”

Molyneux thought that the answer was no, and so did Locke. However, this was not the end of the discussion but just the start of it. Through the ages, the question attracted the attention of many philosophers and scholars, like Berkeley, Leibniz, Helmholtz, William James, etc, to this day. It’s no wonder, for its answer has important implications for the theory of perception. A negative answer, so Gallagher, implies a theory in which a meaningful access to the world is mediated and performed by different sense modalities that have to be coordinated. A positive answer implies a more direct access to the world based on innate properties. But how to get an answer? An empirical solution would be most obvious, but as long as it wasn’t possible to perform eye operations, only a theoretical reply remained. However, in 1728 William Cheselden published an account of a successful cataract operation in which he noted that the boy operated was not able to recognize a cube from a sphere. This pointed to a negative answer. Nevertheless doubts remained on methodological grounds, for it was not clear whether the boy had been able to make valid perceptual judgments because his eyes had not been functioning properly. Also later eye operations followed by tests were not without ambiguities, for example when there were doubts about the onset of the blindness in the cases studied or there was confusion about the experience of the patient after the operation. Therefore a positive or negative answer to the Molyneux problem couldn’t be given. Actually this was not a matter of how to answer the question but of the dearth of patients who met all methodological requirements, especially in the Western countries, where congenitally blind patients are treated ìn infancy, if possible, so that they are not suitable as test persons.

However, how cynical, useful patients can be found in developing countries where medical facilities for early eye operations are often present but many people who need it don’t get it because of inadequate medical services. So, in 2003 Pawan Sinha, a professor at the Massachusetts Institute of Technology, set up a program in India and as a part of it operated successfully five blind patients who met the methodological requirements and tested them. The answer to the Molyneux question was negative: The patients who could distinguish a cube from a sphere by touching them couldn’t do so by perceiving them. The result of the vision test was barely better than if the test persons had guessed.

After three centuries of discussion and testing the conclusion is that man has to learn to see – which was already known from other research, of course –; that a meaningful access to the world is mediated; and that what one sense modality already “knows” is not automatically passed on to another sense modality. Nonetheless, this doesn’t involve that sense modalities function completely independent of each other. For – paraphrasing Gallagher – to take the case of vision discussed here, the structure necessary for seeing has never been used by congenitally blind persons, and therefore the neural networks for seeing are completely absent in their brains, or present only in a rudimentary form. But it is quite well possible, and not unlikely, that congenitally blind people learn to see and discern much faster, once they have been operated, because of what they learned before with the help of their other senses.

Sources:

- Shaun Gallagher, How the body shapes the mind. Oxford: Clarendon Press, 2005; ch. 7.

- John Locke’s Essay ... on http://www.earlymoderntexts.com/assets/pdfs/locke1690book2.pdf ;

- Stanford Encyclopedia of Philosophy, “Molyneux’s Problem”, on https://plato.stanford.edu/entries/molyneux-problem/#5