The concept of a homunculus (Latin for "little man," sometimes spelled "homonculus") is often used to illustrate the functioning of a system. In the scientific sense of an unknowable prime actor, it can be viewed as an entity or agent.
The term appears to have been first used by the alchemist Paracelsus. He once claimed that he had created a false human being that he referred to as the homunculus. The creature was to have stood no more than 12 inches tall, and does the work usually associated with a golem. However, after a short time, the homunculus would turn on its creator and run away. The recipe consisted of a bag of bones, sperm, skin fragments and hair from any animal you wanted it to be a hybrid of. This was to be laid in the ground surrounded by horse manure for forty days, at which point the embryo would form.
A variant method for creating a homunculus cited by other alchemists involved the use of the mandrake. Popular belief held that this plant grew where the semen sometimes ejaculated by hanged men during the last convulsive spasms before death fell to the ground, and its roots vaguley resemble a human form to varying degrees. The root was to be picked before dawn on a Friday morning by a black dog, then washed and "fed" with milk and honey and, in some prescriptions, blood, whereupon it would fully develop into a miniature human which would guard and protect its owner. Yet a third method, cited by Dr. David Christianus at the University of Giessen during the 18th century, was to take an egg laid by a black hen, poke a tiny hole through the shell, replace a bean-sized portion of the white with human sperm, seal the opening with virgin parchment, and bury the egg in dung on the first day of the March lunar cycle. A miniature humanoid would emerge from the egg after thirty days, which would help and protect its creator in return for a steady diet of lavender seeds and earthworms.
The term homunculus was later used in the discussion of conception and birth. In 1694, Nicolaas Hartsoeker discovered "animalcules" in the sperm of humans and other animals. Some claimed that the sperm was in fact a "little man" (homunculus) that was placed inside a woman for growth into a child; these later became known as the spermists. This is not as silly as it sounds today, and neatly explained many of the mysteries of conception (for instance, why it takes two). However it was later pointed out that if the sperm was a homunculus, identical in all but size to an adult, then the homunculus must have sperm of its own. This led to a reductio ad absurdum, with a chain of homunculi "all the way down".
Today the term is used in a number of ways to describe systems that are thought of as being run by a "little man" inside. For instance, the homunculus continues to be considered as one of the major theories on the origin of consciousness, that there is a part (or process) in the brain whose purpose is to be "you". The homunculus is often invoked in cybernetics as well, for similar reasons.
The homunculus is also commonly used to describe the distorted human figure drawn to reflect the relative sensory space our body parts represent on the cerebral cortex. The lips, hands, feet and sex organs are considerably more sensitive than other parts of the body, so the homunculus has grossly large lips, hands and genitals. Well known in the field of neurology, this is also commonly called 'the little man inside the brain.'
A Homunculus argument accounts for a phenomenon in terms of the very phenomenon that it is supposed to explain (Richard Gregory (1987)). Homunculus arguments are always fallacious. In the psychology and philosophy of mind 'homunculus arguments' are extremely useful for detecting where theories of mind fail or are incomplete.
Homunculus arguments are common in the theory of vision. Imagine a person watching a movie. They see the images as something separate from them, projected on the screen. How is this done? A simple theory might propose that the light from the screen forms an image on the retinas in the eyes and something in the brain looks at these as if they are the screen. The Homunculus Argument shows this is not a full explanation because all that has been done is to place an entire person, or homunculus, behind the eye who gazes at the retinas. A more sophisticated argument might propose that the images on the retinas are transferred to the visual cortex where it is scanned. Again this cannot be a full explanation because all that has been done is to place a little person in the brain behind the cortex. In the theory of vision the Homunculus Argument invalidates theories that do not explain 'projection', the experience that the viewing point is separate from the things that are seen. (Adapted from Gregory(1987), (1990)).
Very few people would propose that there actually is a little man in the brain looking at brain activity. However, this proposal has been used as a 'straw man' in theories of mind. Gilbert Ryle (1949) proposed that the human mind is known by its intelligent acts. He argued that if there is an inner being inside the brain that could steer its own thoughts then this would lead to an absurd repetitive cycle or 'regress':
"According to the legend, whenever an agent does anything intelligently, his act is preceded and steered by another internal act of considering a regulative proposition appropriate to his practical problem."
"Must we then say that for the ..[agent's].. reflections how to act to be intelligent he must first reflect how best to reflect how to act? The endlessness of this implied regress shows that the application of the appropriateness does not entail the occurrence of a process of considering this criterion."
Ryle is proposing that if inner reflection were a process then it would be an endless activity if it occurred wholly within the brain (see Ryle's Regress).
However, if the homunculus argument is applied rigorously it should be phrased in such a way that the conclusion is always that if a homunculus is required then the theory is wrong. After all, homunculi do not exist.
The homunculus argument applied to Ryle's theory would be phrased in terms of whether the mental attribute of 'reflecting upon things internally' can be explained by the theory that the mind is 'intelligent acts' without the appearance of a homunculus. The answer, provided by Ryle's own logic, is that internal reflection would require a homunculus to prevent it from becoming an infinite regress. Therefore with these assumptions the Homunculus Argument does not support the theory that mind is wholly due to intelligent acts.
The example of Ryle's theory demonstrates another aspect of the Homunculus Argument in which it is possible to attribute to the mind various properties such as 'internal reflection' that are not universally accepted and use these contentiously to declare that a theory of mind is invalid.
In the classic horror film Bride of Frankenstein, Dr. Frankenstein's old teacher, Dr. Praetorius, shows him his own creations, a series of miniature humanoids kept in specimen jars, including a bishop, a king, a queen, a ballerina, a mermaid, and a devil. These are clearly intended to be forms of homunculi. In his source study of Mary Shelley's original novel upon which the film was based, Prof. Radu Florescu notes that her father, William Godwin was quite familiar with the lives and works of alchemists like Paracelsus and others, and their theories on the creation of the homunculus. Florescu also notes that Konrad Dippel , an alchemist whom he believes may have been the inspiration for Dr. Frankenstein, was a student of Dr. David Christianus.
German horror writer Hanns Heinz Ewers used the mandrake method for creating a homunculus as the inspiration for his 1911 novel, Alraune, in which a prostitute is impregnated with semen from a hanged murderer to create a woman devoid of morals or conscience. Several cinematic adaptations of Alraune have been made over the years, the most recent in 1952 with Erich von Stroheim. The 1995 film Species also appears to draw some inspiration from this variation on the homunculus legend.
In the anime and manga series Fullmetal Alchemist and in the comic Hellboy, the word homunculus describes any man-made human created via alchemy. A homunculus named Roger figures greatly into some of the Hellboy stories.
In the video game Shadow of Memories, Homunculus is the name of an entity that obviously has a great understanding of space and time, and he seems to be helping the main character in the game to escape his death. He seems to be a real homunculus, as his roots seem to be in the age of the alchemists. Very little is known about his past. However, he dresses dark and so are his intentions seemingly.
In The Talons of Weng-Chiang , a 1977 serial from the British television series Doctor Who, the Peking Homunculus is the proper name given to an animated ventriloquist's dummy known as Mr. Sin. The dummy was really an android from the future, with the cerebral cortex of a pig.
In many Role-playing games, a Homunculus is a artificial creature that can be made by magical means to assist the creator. For example in Dungeons & Dragons a wizard can use a spell to make a homunculus. In the Magic: the Gathering card game, two creatures exist with "homunculus" in their name. Both are blue creatures, blue being the color of artificial creation and illusion, among other things.
In the Enix RPG, Valkyrie Profile, the alchemist Lezard Valeth experiments with homonculi. Among them are his minion Bellion, and numerous female elven-like forms kept in large glass tubes.
Florescu, Radu (1975) In Search of Frankenstein. Warner Books, New York.
Gregory, R.L. (1990) Eye and Brain: The Psychology of Seeing, Oxford University Press Inc. New York.
Gregory, T.L. (1987). The Oxford Companion to Mind. Oxford University Press.
Ryle, G. (1949) The Concept of Mind. The University of Chicago Press, 1949.