Ghost in the Shell (攻殻機動隊, Kōkaku Kidōtai, Mobile Armoured Riot Police), is a Japanese science fiction manga created by Masamune Shirow.

In 1995, a motion picture adaptation of the manga was created by Mamoru Oshii. The movie received much attention due to its use of revolutionary computer graphics techniques. The classical style soundtrack was written by Kenji Kawai.

In 2002, a sequel to the manga was released titled Ghost in the Shell 2: Man/Machine Interface (Kōkaku Kidōtai 2: ManMachine Interface; 攻殻機動隊 : 2 ManMachine Interface).

Also in 2002, an anime TV series based on the characters and premises in the manga was created by Kenji Kamiyama, entitled Ghost in the Shell: Stand Alone Complex (攻殻機動隊 STAND ALONE COMPLEX). It featured music from popular composer Yoko Kanno. In late 2004 the first season was adapted and released to the American market on Adult Swim, and a second season (Ghost in the Shell: Stand Alone Complex 2nd GIG) began to air.

In 2004, a second movie, Innocence: Ghost in the Shell was released; the date was March 6 in Japan and September 17 in the U.S.

Setting

Set in the 21st century, Ghost in the Shell is superficially a futuristic spy thriller, dealing with the exploits of Motoko Kusanagi, a member of the covert operations section of the Japanese National Public Safety Commission, Section 9, which specializes in fighting technology-related crime. Although supposedly equal to all other members, Kusanagi fills the leadership role in the team, and is usually referred to as "Major" due to her past rank in the armed forces. She is capable of superhuman feats, and specialized for her job; her body is almost completely mechanized, save her brain and a single spinal cord segment.

The setting of Ghost in the Shell is distinctively cyberpunk or postcyberpunk, similar to that of William Gibson's Sprawl trilogy and other post/cyberpunk works, though Shirow's work is focused more tightly on the ethical and philosophical ramifications of the widespread merging of humanity and technology. The development of artificial intelligence and an omnipresent computer network set the stage for a reevaluation of human identity and uniqueness. The manga in particular tackles these questions head on: Kusanagi and her colleagues face external threats and also suffer internal conflict over their own natures.

The overarching story of the manga (and the only story of the first movie) is of the hunt for a cyber-criminal, "The Puppet Master", real identity unknown, who commits a large number of crimes through a single modus operandi: "ghost hacking", breaking into and taking control of human minds. As the agents of Section 9 start to unravel the mystery of the Puppet Master, it becomes clear that it is no ordinary criminal, but a unique autonomous artificial intelligence project (Top Secret Project 2501) created by another government agency, the Ministry of Foreign Affairs (MFA), also known as Section 6. Puppet Master escapes Section 6 servers in pursuit of his evolution through merging with Kusanagi. Kusanagi, although initially skeptical, finally agrees to allow the Puppet Master to merge with her own consciousness, sharing her body, in what is no doubt intended to raise even more questions about the nature of human identity in a world where human consciousness is no longer unique.

The manga is also notable for the proliferance of footnotes and commentary by Shirow himself on both the technology and the socio-political background of the setting (in the complete, English language graphic novel edition, these take up more than 30 pages).

The philosophy of Ghost in the Shell

Ghosts

Ghost is a colloquial slang term for an individual's mind or essence of being. In the futuristic society of Ghost in the Shell, the term has scientifically redefined the "soul", or ghost, as what differentiates a human being from a biological robot. Regardless of how much biological material is replaced with electronic or mechanical substitutes, as long as an individual retains their ghost, they retain their humanity and individuality.

The concept of ghost was borrowed by Masamune Shirow from the essay of structuralism The Ghost in the Machine by Arthur Koestler. The title The Ghost in the Machine itself was originally words used by a British philosopher, Gilbert Ryle, mocking the paradox of the conventional Cartesian dualism and Dualism in general. Koestler, like Ryle, denies the Cartesian dualism and resorts the origin of human mind to the physical condition of the brain.

Shirow follows this course of philosophy of denying dualism in his work. Based on Koestler's idea, in Ghost in the Shell, Shirow defines in a broader context ghost not simply as a physical trait, but a phase or rather vaguely a phenomenon that appears in a system of a certain level of complexity. The brain itself is only part of the whole neural network; so if an organ is removed from a body for instance, the autonomic nerve of the organ and consequently its ghost will vanish unless the stimulus of the existence of the organ is re-produced thoroughly realistically by a certain mechanical substitution. This could be compared to an analogy of a person with innate hearing disability being unable to understand the concept of "hearing" unless taught.

In Ghost in the Shell, Kusanagi completely reproduces her stimulus of her entire organs including internal organs to maintain her ghost. In case of a technical transferring of a ghost from one body to another, the attempt normally results in failure since the ghost tends to deteriorate due to either the difference of system at the material level or the deficiency of the transferring protocol. The Puppet Master manages not to deteriorate its ghost when merging with Kusanagi because his system is the body of information itself, thereby avoiding a deterioration due to the deficiency at material level.

Hegel's concept of Geist may also be related.

Another interpretation of the fusion of Kusanagi and the Puppet Master is more analogous to the concept of Birth where two separate entities create a third entity which is not the same as either of the originating Ghosts/DNA sets but shares common traits. The Puppet Master does not wish to merely save himself from termination, to do so he could simply ask Kusanagi to give him shared space in her memory cores that she could offload later into another robotic receptacle. He quite specifically asks her to fuse her "ghost" or "soul" with his own, a form of marriage/birth in which the resultant being is neither the Puppet Master nor Kusanagi but a new being entirely. This touches upon concepts of birth, immortality through progeny, and the union of two ghosts/people in the creation of progeny.

Throughout the story the cyborg characters, being more or less a human brain with a manufactured body, contemplate individually and together what being human really is, and how a soul or ghost is truly defined. The Puppet Master is an AI, yet they recognize traits and personality within his mind structure that are clearly analogous to a human soul or ghost image. They cannot discount this similiarity as it is very clearly analysed by their medical scanning tools when they first capture the Puppet Master. The members of Section 9 must re-evaluate their own tenuous hold on the idea of humanity and "self", when faced with a being who clearly is self directed and has a ghost but was originated as a complex program not a DNA organism.

AI as a step in evolution

A very important concept within this work is that evolution is the process of fusing (procreation) two sets of data (DNA) in order to create a 3rd set of data which contains the most vital elements of the original organisms along with some element of chance. The Puppet Master has evolved beyond DNA as a data set and thus to procreate (his true desire and purpose for leaving the net in the first place) this new organism (a soul not born of DNA) a new paradigm of data merging needs to be contemplated for which he has sought Kusanagi out. This is a merger of two operating "souls" or "ghosts" into one mind, which is specifically different than birth while being analogous to it at the same time.

Extended sequences in an old museum in the film version contemplate life as an evolutionary step to creating AI, differing significantly from the content of the same sequence in the manga.

De-Ghosting

One of the consequences of this revelation is a final resolution of the nature versus nurture debate in criminology. When a criminal is convicted of a crime in Masamune Shirow's future world, a detailed technical analysis is done of the subject. If it is discovered that the crime was committed due to a material defect in either the biological or electronic components of the convict's brain, the defect is repaired and the convict is released. If, instead, the crime is determined to have been the result of an individual's ghost, then there is only one cure: the removal of the portion of the brain that communicates with the soul, thereby de-ghosting the criminal and preventing any possibility of future criminal behavior.

Tachikoma/Fuchikoma

Tachikoma (they are called Tachikoma in Stand Alone Complex, but called Fuchikoma in the original Manga) are artificially intelligent mini-tanks (walkers) employed by Section 9. Because of the demands of field duty, these robots are constructed with extremely flexible, adaptable AIs that lack many of the safeguards present in other artificially intelligent robots. While this enables them to behave unpredictably and flexibly, it also presents difficulties for the members of Section 9, who must monitor the Fuchikoma closely for signs of undesirable emotional development.

The underlying statement here is that predictable behavior results in inherent weakness. Section 9, as an organization, needs heterogeneity and even organic weakness if it is to survive. "A machine where all the parts respond the same way is a brittle tool."

Cyberbrain warfare/Ghost hacking

Cyberbrain warfare is the practice of employing ghost hacking as a means of gaining access to an opponent's cyberbrain, and ultimately, their ghost. A successful cyberhacker can intercept, censor, or augment the sensory information being received by a victim, or even go so far as to destroy or rewrite complete memories.

Cyberbrain warfare is portrayed as a natural consequence of the integration of cybernetic and wireless communication technology directly into the human brain. Despite the apparent risks, even the most paranoid characters in the story find the benefits of directly networking their brains to be indispensable.

Apparently, any conduit by which information is absorbed by the brain can be exploited for ghost hacking. Shirow envisions the use of firewalls for protecting the ghost against attack, and multiple layers of encryption.

Film adaptations