Nobody believed him. His family told him to get help. But Timothy Trespas, an out-of-work recording engineer in his early 40s, was sure he was being stalked, and not by just one person, but dozens of them.

This monster’s talent for mimicry provokes some of the darkest questions. By foregrounding this capability and coupling it with our inability to discern mimics from the remaining men, The Thing focuses dread light on a question which has haunted thinkers for ages: the “problem of other minds.” How can anyone know if other people actually have selves? What would enable you to tell the difference between your neighbor and a well-programmed robot? Thinkers have posited answers (including the notion that its insolvable nature means we must move on from it), but the question has not been laid to rest. Indeed, the quandary has proven to be a cornucopia of paranoiac fantasies, an essential theme in science-fiction and horror in particular. The Thing shares intellectual DNA with movies like The Invasion of the Body Snatchers and David Cronenberg’s eXistenZ, as well as literature by Poe, Kafka and virtually every piece of fiction penned by Philip K. Dick. This movie, though, has the distinction of being based on source material which pre-dates most of our great works of paranoia. Had The Thing stopped here, focusing on a hidden presence lurking beneath the face of friends and co-workers, it may have still been remembered as a fine work of psychological suspense. This movie brings something else to the cinematic table, a visual excess to counter-balance these narrative ambiguities. Carpenter, drawing heavily on the source material, rejuvenates the paranoiac nightmare with an infusion of gore and unexpected (almost unimaginable) violence.

In the late 1950s, psychologist Milton Rokeach was gripped by an eccentric plan. He gathered three psychiatric patients, each with the delusion that they were Jesus Christ, to live together for two years in Ypsilanti State Hospital to see if their beliefs would change. The early meetings were stormy. "You oughta worship me, I'll tell you that!" one of the Christs yelled. "I will not worship you! You're a creature! You better live your own life and wake up to the facts!" another snapped back. "No two men are Jesus Christs. … I am the Good Lord!" the third interjected, barely concealing his anger.

Frustrated by psychology's focus on what he considered to be peripheral beliefs, like political opinions and social attitudes, Rokeach wanted to probe the limits of identity. He had been intrigued by stories of Secret Service agents who felt they had lost contact with their original identities, and wondered if a man's sense of self might be challenged in a controlled setting.

figure i : he stands opposite his rivals

You are the only one who can never see yourself apart from your image. In the reflection of a mirror, or the pigment of the photograph you entertain yourself. Every gaze you cast is mediated by a looking apparatus, by an image you must stand alongside. The gaze welcomes itself as a guest. The eye orders you to sit at its table, to share in the feast of one's own image. The image stands beside the real, all the while eating at its table, stealing morsels from the feast it enables. The image is not reality, but the image is the only gesture you have in the direction of reality.

From the Greek pará-noos, he who suffers from paranoia has a mind beside itself. He is convinced that his partner conspires against him: a belief in turn organised by a conspiring mentality. I am confident that you are reading my mind: a position founded by my supposed reading of yours. The paranoid stand beside themselves; a part beside itself as part, conspiring against the whole. Paranoia is a kind of paradox, from the Greek pará-doxon, it stands beside the orthodox.

From the Greek pará-sītos, the parasite is a figure who feeds beside, an uninvited guest who eats at the host's table nonetheless. I display my feast openly, in order that my status be established to the community I consider myself a part. The world outside never ceases at its attempt to gain access to my table. Here I consider to offer them a seat, to share my feast. Here I cast a hand skyward, signalling my absolute negation of their status as a guest. The boundary between my feast and theirs is drawn. As the host I set the conditions under which my body stands beside. My body is entire, but it is also part. I stand beside my community, a conglomerate of bodies, each themselves parts of a greater whole.

The parasite inhabits the host, breaching the boundary of the body in order to organise a new ecosystem around their own, distinct, metabolism. The parasite feeds on the body of its host. Some parasites alter their host's body chemistry, perhaps affecting a biological shift from male to female, from alpha to drone, so that the parasite's offspring have a better chance at survival. In order that the parasite enter the next stage in its life-cycle, it is often unimportant that the host survives.

figure iii : his faithful companion is always at his side

From the Greek pará-digme, the paradigm is literally "what shows itself beside". Parasite, paranoid, paradox constitute a class of forms, standing beside one another, each in relation to the whole. They constitute a paradigm that organises the manner of their know-ability. To overturn the paradigm, one must stand beside it, constituting a reordering of knowing from the outside in.

These are the figures set beside each other: the host and the guest; the mind and its image; the belief as its own antithesis. But these are also a series of relations, figured by a paradigm. It may well seem natural to consider the host and the guest, the mind and its image – indeed the words come in pairs, set side by side on the printed page, or expressed as isolated figures of breath by the speaking subject. Once a relation is figured it becomes difficult to consider the isolated, the individual in opposition. After all, biological evolution has shown countless times, again and again, that an uninvited guest can become an accomplice; that a parasitic burden can become a treasured constituent of one's own body. Parasitism is often indistinguishable from symbiosis. Buddhism teaches that the greatest oneness can only come when the division between mind and self-image has been obliterated. To defuse one's paranoia, it is necessary to stand outside oneself, to places one's state of mind beside itself as paradox, to break the condition of division.

Welcoming the parasite to your table requires you to see your body as their body. At the feast we coalesce, my guest and I. Overturning our differences through the manner of their know-ability. True symbiosis stands beside invitation. True symbiosis is a politics aware of its own difference; a paradigm shown beside itself (together again for the first time).

figure iv : some of the things read (side by side)

• What is a Paradigm? (essay) by Giorgio Agamben
• The Parasite (book) by Michel Serres
• Paranoid Reading and Reparative Reading (chapter) by Eve Kosofsky Sedgwick

When, one evening in 1976, Philip K. Dick invited Tim Powers to his Fullerton apartment, the Cal State student expected the kind of night he often passed with the science-fiction titan: a wide-ranging conversation, fueled by wine and beer, about religion, philosophy and Beethoven.

The night began the usual way. But it took a strange turn as Dick's wife, Tessa, and her brother began grabbing lamps and chairs. "She and her brother were carrying things out of the house," recalls Powers. "I said, 'Phil, they're taking stuff, is this OK?' "

" 'Powers, let me give you some advice, in case you should ever find yourself in this position,' Dick said. 'Never oversee or criticize what they take. It's not worth it. Just see what you've got left afterward, and go with that.'

"And then," Powers recalls, "her brother said, 'Could you guys lift your glasses? We want the table.' "

Dick was an old hand at marital dissolution. Tessa had reached her breaking point, and that evening marked the beginnin