Molyneux's Problem (Stanford Encyclopedia of Philosophy)

Molyneux's Problem (Stanford Encyclopedia of Philosophy) http://plato.stanford.edu/entries/molyneux-problem/

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Molyneux's ProblemFirst published Thu 30 Jun, 2005

On 7 July 1688 the Irish scientist and politician William Molyneux(1656-1698) sent a letter to John Locke in which he put forward a problemwhich was to awaken great interest among philosophers and other scientiststhroughout the Enlightenment and up until the present day. In brief, thequestion Molyneux asked was whether a man who has been born blind andwho has learnt to distinguish and name a globe and a cube by touch, wouldbe able to distinguish and name these objects simply by sight, once he hadbeen enabled to see.

1. Molyneux's Formulation of the Problem2. Eighteenth-Century Philosophical Discussions about Molyneux's Problem3. The First Experimental Data4. Empirical Approaches in the Nineteenth Century5. Modern Approaches6. ConclusionBibliographyOther Internet ResourcesRelated Entries

1. Molyneux's Formulation of the ProblemAs is apparent from both his writings and his lectures, Molyneux was highlyinterested in optics and in the psychology of sight. To some extent thissimply reflects the general attitude of his time: optics was a subject that wasthen engaging the attention of a number of leading scientists. His interestalso had a more personal background, however, for his wife had lost her sightin the first year of their marriage. The immediate cause of his formulating theproblem and sending it to Locke is to be found in Locke's French extract ofAn Essay Concerning Humane Understanding, published in 1688 in theBibliothque Universelle & Historique. In this extract Locke distinguished


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between ideas we acquire by means of one sense and those we acquire bymeans of more than one sense. He maintained that someone who lacks asense will never be able to acquire the ideas pertaining to it. A blind man, forexample, will never be able to have any idea of colour. Among the ideas weare able to acquire by means of a combination of senses, Locke reckonedthose of space, rest, motion and figure. Molyneux's problem had to do withthe last of these. Molyneux was probably inspired by Locke's exposition ofthe ideas of persons born blind and the ideas which can be acquired bymeans of both sight and touch. He was, moreover, a great admirer of Locke.

On Saturday 7 July 1688 William Molyneux wrote a letter to John Lockesetting out for the first time his problem concerning the person born blind:

Dublin July. 7. 88

A Problem Proposed to the Author of the Essai Philosophiqueconcernant L'Entendement

A Man, being born blind, and having a Globe and a Cube, nigh ofthe same bignes, Committed into his Hands, and being taught orTold, which is Called the Globe, and which the Cube, so as easilyto distinguish them by his Touch or Feeling; Then both beingtaken from Him, and Laid on a Table, Let us Suppose his SightRestored to Him; Whether he Could, by his Sight, and before hetouch them, know which is the Globe and which the Cube? OrWhether he Could know by his Sight, before he stretch'd out hisHand, whether he Could not Reach them, tho they were Removed20 or 1000 feet from Him?

If the Learned and Ingenious Author of the Forementiond Treatisethink this Problem Worth his Consideration and Answer, He may at any time Direct it to One that Much Esteems him, and is,

His Humble Servant William Molyneux

High Ormonds Gate in Dublin. Ireland

For reasons unknown Locke never replied to the letter. However, a couple ofyears later, after the two men had started an amicable correspondence,Molyneux returned to his problem. This time with success. In his letter,dated 2 March 1693, Molyneux presented Locke with his problem, thoughin a somewhat altered form, asking Locke if he could perhaps find someplace in his Essay to say something about it. This time Locke reacted withenthusiasm: "Your ingenious problem will deserve to be published to theworld." From the second edition of his Essay (that of 1694) Locke included


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Molyneux's problem in his work and thereby made it accessible to a wideraudience:

Suppose a Man born blind, and now adult, and taught by histouch to distinguish between a Cube, and a Sphere of the samemetal, and nighly of the same bigness, so as to tell, when he feltone and t'other; which is the Cube, which the Sphere. Supposethen the Cube and Sphere placed on a Table, and the Blind Manto be made to see. Qaere, Whether by his sight, before he touch'dthem, he could now distinguish, and tell, which is the Globe,which the Cube.

In this formulation Molyneux's problem attracted the attention of lots ofphilosophers and other men of learning, such as Berkeley, Leibniz, Voltaire,Diderot, La Mettrie, Helmholtz and William James. In which ways did theyapproach the problem?

2. Eighteenth-Century Philosophical Discussions about Molyneux's ProblemIn the first instance, philosophers considered it to be impossible that a manborn blind should be able to acquire sight. They regarded Molyneux'sproblem as a kind of thought-experiment, which was to be dealt with byratiocination alone. The arguments put forward were usually concerned withthe relation between visual and tactual sensations or between visual andtactual notions of the form of objects.

All these philosophers assumed that the visual and tactual sensations of anobject differ from each other, but there was no agreement concerning therelation between the two. Some, Berkeley for instance, believed that thisrelation is arbitrary and based only on experience. Others, such as Lee andSynge, thought that it is necessary and perceived directly, while yet others,such as Molyneux and Locke, thought that it is necessary and learned byexperience. Opinions were also divided concerning the relation betweenvisual and tactual notions of objects. Some philosophers defended theposition that the visual and tactual notions of a globe differ from oneanother, and can only be related by either experience or reason (the latterview was defended by Reid). Others believed that the visual and the tactualnotion of a globe are actually the same, or have something in common whichis either observed directly (Boullier and Hutcheson) or inferred by reason(Leibniz).

Investigating how the different positions correlate with the answers given toMolyneux's question, one can conclude as follows. Empiricists such as


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Molyneux, Locke and Berkeley answered in the negative. More rationalistphilosophers such as Synge, Lee and Leibniz gave an affirmative answer.There was no unanimous solution, amongst others because Molyneux'sproblem was interpreted in different ways. Some philosophers thought thatthe man born blind had to answer directly, while others were of the opinionthat he should be able to make use of his memory and reason, and that heshould be at liberty to view all sides of the objects by walking around them.Some philosophers believed that the question implied that the man shouldbe told in advance that he would be presented with a globe and cube,whereas others thought that he should not be provided with this information.

3. The First Experimental DataDiscussion concerning Molyneux's problem took a new turn once theEnglish surgeon and anatomist William Cheselden (1688-1752) publishedan account of what a congenitally blind person had seen after his cataractshad been removed (1728). The publication led philosophers to regard theMolyneux problem no longer as a simple thought-experiment, but as aquestion which could be answered by experimentation.

In his account, Cheselden noted that when the boy was first able to see, hedid not know the shape of a thing and could not recognize one thing fromanother, regardless of how different in shape or magnitude they were. Somephilosophers thought that Cheselden's observations were unequivocal andthat they confirmed the hypothesis that a blind man restored to sight wouldnot be able to distinguish objects and would have to learn to see. Most ofthese philosophers, we might mention Voltaire, Camper and the elderCondillac as examples, were adherents of Berkeley's theory of vision, whichhad predicted a similar outcome.

Others, however, such as La Mettrie and Diderot, regarded Cheselden'saccount as wholly ambiguous in its implications. They pointed out that itwas possible that the boy had been unable to make valid perceptualjudgments because his eyes had not been functioning properly. Theysuggested that this could have been due to the fact that his eyes had notbeen used for a long time, or to their not having had enough time to recoverfrom the operation. They pointed out that Cheselden had, perhaps, asked theboy leading questions. Some philosophers also believed that the results ofthe inquiry depended on the intelligence of the patient.

Those who criticised the significance of Cheselden's account in this way(most of them were French philosophes) made proposals as to how to avoidthe problems mentioned. They suggested that one should prepare the patientcarefully for the operation and for the interrogation, that one should allow


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his eyes time to recover from the operation and that one should give him theopportunity to exercise his eyes in darkness. What is more, one should avoidasking leading questions.

Some philosophers were even more radically critical of operations like thatperformed by Cheselden. Mrian, for example, noticed that Cheselden'sobservations, like all observations of blind people whose cataracts havebeen extracted, present difficulties because cataracts do not cause completeblindness and complete blindness cannot be cured. It could not beconcluded from this that Molyneux's problem could not be solvedexperimentally, however, for it could be maintained that patients operatedupon for cataracts are directly relevant to the solution of it. They are unableto perceive form before they are operated upon, and the essential issue atstake when posing Molyneux's problem is the ability to distinguish andname forms. This is a point of view which was taken by many philosophers.

4. Empirical Approaches in the Nineteenth CenturyAbout 1800 several developments occurred which justify the speaking of anew period in the history of Molyneux's problem. New accounts of patientsoperated on for cataracts were published, and shed fresh light on the issue.Whereas Cheselden had only noticed what his patient observed in more orless natural circumstances, later ophthalmologists performed experimentswhich showed whether their patients were able to see form, size, distance,etc. Some, such as Franz and Nunneley, were especially interested inMolyneux's problem as such, and performed experiments with the prescribedglobe and cube. Some of the reports were in agreement with that ofCheselden, others conflicted with it. The cases could not easily be compared,however, since the pre- and post-operative circumstances differed to such agreat extent. As one might have expected, an extended scale of possiblesolutions to the Molyneux problem was brought under consideration.

What is more, specialists also began to consider observations concerning thesight of newly born animals and babies when discussing Molyneux'sproblem. Some of those doing research in the field, such as Adam Smith andJohannes Mller, supposed that the sight of young animals could becompared with that of a person who had been made to see. The fact thatcertain animals see objects at a distance as soon as they are born suggestedthat Molyneux's question could be answered affirmatively. This turned outto be a strong argument against Berkeley's theory of vision. Others, ThomasBrown for instance, were of the opinion that the visual behaviour of babiescould be compared with that of a blind person who had been operated uponand made to see. They were convinced that in both cases seeing has to be


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learned, and that Molyneux's question had, therefore, to be answered in thenegative.

Wheatstone's discovery that the perception by sight of the third dimensionof space is immediate, was used as a reason for answering Molyneux'squestion affirmatively. The discovery was also regarded as disprovingBerkeley's theory of vision.

The data concerning the sight of patients who had been operated upon forcataracts, and of young animals and infants, were used as evidence in thedebate concerning the question of whether the perception of space is innateor acquired. Although Molyneux's problem was frequently discussed in thisdebate, there was still no agreement on the right solution to it.

5. Modern ApproachesDuring the course of the twentieth century, the main interest in Molyneux'sproblem has been historical. Biographers and commentators dealing withwell-known philosophers have analysed the solutions they proposed for it.Molyneux's problem has also turned up frequently in textbooks and generalhistories of psychology, ophthalmology, neurophysiology, etc. A fewauthors have written brief and incomplete histories of the problem. Degenaar(1996) has written a comprehensive survey of the history of the discussionabout Molyneux's problem. Riskin (2002) described Molyneux's problem inthe wider context of the Enlightenment.

Philosophers, psychologists and other scientists have also tried to solve theMolyneux problem by making use of alternative approaches, both old andnew. They have, for example, made use of various accounts of recovery fromearly blindness. As was to be expected, these proved to be as problematicand inconclusive as were their predecessors in the eighteenth and nineteenthcenturies.

The Molyneux problem has also been tackled by methods more amenable toexperimental control than is possible in clinical studies, namely by rearinganimals in darkness. Visual deprivation experiments have shown that duringthe development of the visual system there is a certain critical period inconnection with the presentation of light patterns. During this period,changes brought about by deprivation can be reversed. If exposure to light ispostponed for too long, however, the development of normal visualmechanisms will be extremely difficult, if not impossible. Although theresults of deprivation experiments are not relevant to the solution ofMolyneux's problemMolyneux supposed that his blind man had a goodvisual system, whereas that of deprived animals is abnormalthey have


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been used as evidence for Locke's position.

A recent approach to Molyneux's problem involves the use of sensorysubstitution devices, developed in the context of corporeal mobility orreading (Morgan, 1977). Learning how to use sensory substitution systemshas been considered a good approximation to Molyneux's problem, sincesuch systems present information normally handled by one modality, such asvision, to another sense, typically audition or touch, using forms of codingnovel to the user. Experiments with sensory substitution systems show thatsubjects need some time to learn to distinguish and identify objects, and thishas been interpreted as a confirmation of the position of Molyneux andLocke. Some researchers have stressed the fact that a sensory aid is not,strictly speaking, a new modality, and that to learn to use such devices isonly an approximation to Molyneux's problem, depending as it does uponthe raising of similar issues.

Another variation of Molyneux's problem was suggested by Evans (1985).He wondered whether the visual cortex of a patient with congenitalblindness could be electrically stimulated in such a way that the patientexperiences a pattern of light flashes (phosphenes) in the shape of a square orcircle. This question has been investigated experimentally, but the results donot provide a final answer to Molyneux's question (see Jacomuzzi, Kobauand Bruno 2003 for discussion).

There is one author who believes that no new approach is necessary:Gallagher (2005, ch. 7) argues that developmental psychology andneurophysiology have progressed sufficiently far to enable us to answerMolyneux's question once and for all. He claims that Locke was right, but forthe wrong reasons. However, it remains to be seen whether this will be thelast word.

6. ConclusionThe history of the issues surrounding Molyneux's question shows that thequestion was not as easy to answer as Molyneux himself may have assumed.On the contrary, there is no problem in the history of the philosophy ofperception that has provoked more thought than the problem that Molyneuxraised in 1688. In this sense, Molyneux's problem is one the most fruitfulthought-experiments ever proposed in the history of philosophy, which isstill as intriguing today as when Molyneux first formulated it more thanthree centuries ago.

Bibliography


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Cheselden, W., 1728, An Account of some Observations made by ayoung Gentleman, who was born blind, or lost his Sight so early, thathe had no Remembrance of ever having seen, and was couch'd between13 and 14 Years of Age, Philosophical Transactions, 402: 447-450.Degenaar, M.J.L., 1996, Molyneux's Problem: Three Centuries ofDiscussion on the Perception of Forms, Dordrecht: Kluwer AcademicPublishers.Evans, G., 1985, Molyneux's Question, in Gareth Evans: CollectedPapers, A. Phillips (ed.), Oxford: Clarendon Press.Gallagher, S., 2005, How the Body Shapes the Mind, Oxford:Clarendon Press.Jacomuzzi, A.C., Kobau, P., Bruno, N., 2003, Molyneux's questionredux, Phenomenology and the Cognitive Sciences 2: 255-280.Locke, J., 1688, Extrait d'un Livre Anglois qui n'est pas encore publi,intitul Essai Philosophique concernant l'Entendement, o l'on montrequelle est ltendu de nos connoissances certaines, & La manire dontnous y parvenons, Bibliothque Universelle & Historique, 8: 49-142, Amsterdam: Chez Wolfgang, Waesberge, Boom, et Van Someren.-----, 1693, Letter to William Molyneux, 28 March, in TheCorrespondence of John Locke (9 vols.), E.S. de Beer (ed.), Oxford:Clarendon Press, 1979, vol. 4, no. 1620.-----, 1690, An Essay Concerning Humane Understanding, London,printed by Eliz. Holt, for Thomas Basset. Second edition 1694. Fourthedition 1700, edited with an Introduction by P.H. Nidditch, Oxford:Clarendon Press, 1975.Molyneux, W., 1688, Letter to John Locke, 7 July, in TheCorrespondence of John Locke (9 vols.), E.S. de Beer (ed.), Oxford:Clarendon Press, 1978, vol. 3, no. 1064.-----, 1693, Letter to John Locke, 2 March, in The Correspondence ofJohn Locke (9 vols.), E.S. de Beer (ed.), Oxford: Clarendon Press, 1979,vol. 4, no. 1609.Morgan, M.J., 1977, Molyneux's Question: Vision, Touch and thePhilosophy of Perception, Cambridge: Cambridge University Press.Riskin, J., 2002, Science in the Age of Sensibility: The SentimentalEmpiricists of the French Enlightenment, Chicago and London: TheUniversity of Chicago Press.Senden, M. Von., 1932, Raum- und Gestaltauffassung bei operiertenBlindgeborenen, Leipzig: Barth. Translated by P. Heath: Space and Sight: The Perception of Space and Shape in the Congenitally BlindBefore and After Operation, London, Methuen, 1960.Simms, J.G., 1982, William Molyneux of Dublin: A Life of theSeventeenth-Century Political Writer & Scientist, Blackrock: IrishAcademic Press. Edited by P.H. Kelly.

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Molyneux's Problem (Stanford Encyclopedia of Philosophy)