Suppose a surgeon tells a patient who is about to undergo a knee operation that when he wakes up he will feel a sharp pain. When the patient wakes up, the surgeon hears him groaning and contorting his face in certain ways. Although we are naturally inclined to say that the surgeon knows what the patient is feeling, there is a sense in which he does not know, because he is not feeling that kind of pain himself. Unless he has undergone such an operation in the past, he cannot know what his patient feels. Indeed, the situation is more complicated than this, for even if the surgeon has undergone such an operation, he cannot know that what he felt after his operation is the same sort of sensation as what his patient is feeling now. Because each person’s sensations are in a sense “private,” for all the surgeon knows, what he understands as pain and what the patient understands as pain could be very different. (Similar remarks apply to our use of colour terms. For all a person knows, the colour sensation he associates with “green” could be very different from the sensations other people associate with that term. This possibility is known as the problem of the inverted spectrum.)
It follows from this analysis that each human being is inevitably and even in principle prevented from having knowledge of the minds of other human beings. Despite the widely held conviction that in principle there is nothing in the world of fact that cannot be known through scientific investigation, the other-minds problem shows to the contrary that an entire domain of human experience is resistant to any sort of external inquiry. Thus, there can never be a science of the human mind.
Close-up-of-two-straws-in-a-glass-of-waterClose-up of two straws in a glass of water. The straws appear bent owing to the refraction of light.[Credits : Steve Lupton/Corbis]
Plato-marble-portrait-bust-from-an-original-of-the-4thPlato, marble portrait bust, from an original of the 4th century bc; in the Capitoline Museums, …[Credits : © Gianni Dagli Orti/Corbis]
Detail-of-a-Roman-copy-of-a-Greek-alabaster-portraitDetail of a Roman copy (2nd century bc) of a Greek alabaster portrait bust of Aristotle (c. …[Credits : A. Dagli Orti/© DeA Picture Library]
St-Augustine-reading-the-epistles-of-St-Paul-fresco-bySt. Augustine reading the epistles of St. Paul, fresco by Benozzo Gozzoli, 1468; in the church of …[Credits : Scala/Art Resource, New York]
Rene-Descartes-lithograph-19th-centuryRené Descartes, lithograph, 19th century.[Credits : The Granger Collection, New York]
David-Hume-oil-painting-by-Allan-Ramsay-1766-in-theDavid Hume, oil painting by Allan Ramsay, 1766; in the Scottish National Portrait Gallery, …[Credits : Courtesy of the Scottish National Portrait Gallery]
Immanuel-Kant-pencil-portrait-by-Hans-Veit-Schnorr-von-CarolsfeldImmanuel Kant, pencil portrait by Hans Veit Schnorr von Carolsfeld; in the Kupferstichkabinett, …[Credits : Marburg/Art Reference Bureau]
Edmund-Husserl-1930Edmund Husserl, c. 1930.[Credits : Archiv für Kunst und Geschichte, Berlin]
We welcome your comments. Any revisions or updates suggested for this article will be reviewed by our editorial staff. Contact us here.
Regular users of Britannica may notice that this comments feature is less robust than in the past. This is only temporary, while we make the transition to a dramatically new and richer site. The functionality of the system will be restored soon.