Posthuman or post-human is a concept originating in the fields of science fiction, futurology, contemporary art, and philosophy that literally means a person or entity that exists in a state beyond being human. The concept addresses questions of ethics and justice, language and trans-species communication, social systems, and the intellectual aspirations of interdisciplinarity. "Posthumanism" is not to be confused with "transhumanism" (the biotechnological enhancement of human beings) and narrow definitions of the posthuman as the hoped-for transcendence of materiality.
In critical theory, the posthuman is a speculative being that represents or seeks to re-conceive the human. It is the object of posthumanist criticism, which critically questions Renaissance humanism, a branch of humanist philosophy which claims that human nature is a universal state from which the human being emerges; human nature is autonomous, rational, capable of free will, and unified in itself as the apex of existence. Thus, the posthuman position recognizes imperfectability and disunity within him or herself, and understands the world through heterogeneous perspectives while seeking to maintain intellectual rigour and a dedication to objective observations. Key to this posthuman practice is the ability to fluidly change perspectives and manifest oneself through different identities. The posthuman, for critical theorists of the subject, has an emergent ontology rather than a stable one; in other words, the posthuman is not a singular, defined individual, but rather one who can "become" or embody different identities and understand the world from multiple, heterogeneous perspectives.
Steve Nichols published the Post-Human Manifesto in 1988, and holds a contrarian view that human beings are already post-human compared to previous generations.
Critical discourses surrounding posthumanism are not homogeneous, but in fact present a series of often contradictory ideas, and the term itself is contested, with one of the foremost authors associated with posthumanism, Manuel de Landa, decrying the term as "very silly." Covering the ideas of, for example, Pepperell's The Posthuman Condition, and Hayles's How We Became Posthuman under a single term is distinctly problematic due to these contradictions.
The posthuman is roughly synonymous with the "cyborg" of A Cyborg Manifesto by Donna Haraway. Haraway's conception of the cyborg is an ironic take on traditional conceptions of the cyborg that inverts the traditional trope of the cyborg whose presence questions the salient line between humans and robots. Haraway's cyborg is in many ways the "beta" version of the posthuman, as her cyborg theory prompted the issue to be taken up in critical theory.
Following Haraway, Hayles, whose work grounds much of the critical posthuman discourse, asserts that liberal humanism - which separates the mind from the body and thus portrays the body as a "shell" or vehicle for the mind - becomes increasingly complicated in the late 20th and 21st centuries because information technology put the human body in question. Hayles maintains that we must be conscious of information technological advancements while understanding information as "disembodied," that is, something which cannot fundamentally replace the human body but can only be incorporated into it and human life practices.
The posthuman is a being that relies on context rather than relativity, on situated objectivity rather than universal objectivity, and on the creation of meaning through 'play' between constructions of informational pattern and reductions to the randomness of on-off switches, which are the foundation of digital binary systems.
According to transhumanist thinkers, a posthuman is a hypothetical future being "whose basic capacities so radically exceed those of present humans as to be no longer unambiguously human by our current standards."
Posthumans could be completely synthetic artificial intelligences, or a symbiosis of human and artificial intelligence, or uploaded consciousnesses, or the result of making many smaller but cumulatively profound technological augmentations to a biological human, i.e. a cyborg. Some examples of the latter are redesigning the human organism using advanced nanotechnology or radical enhancement using some combination of technologies such as genetic engineering, psychopharmacology, life extension therapies, neural interfaces, advanced information management tools, memory enhancing drugs, wearable or implanted computers, and cognitive techniques.
As used in this article, "posthuman" does not necessarily refer to a conjectured future where humans are extinct or otherwise absent from the Earth. As with other species who speciate from one another, both humans and posthumans could continue to exist. However, the apocalyptic scenario appears to be a viewpoint shared among a minority of transhumanists such as Marvin Minsky and Hans Moravec, who could be considered misanthropes, at least in regards to humanity in its current state. Alternatively, others such as Kevin Warwick argue for the likelihood that both humans and posthumans will continue to exist but the latter will predominate in society over the former because of their abilities. Recently, scholars have begun to speculate that posthumanism provides an alternative analysis of apocalyptic cinema and fiction, often casting vampires, werewolves and even zombies as potential evolutions of the human form and being.
Many science fiction authors, such as Greg Egan, H.G Wells, Bruce Sterling, Frederik Pohl, Greg Bear, Charles Stross, Neal Asher, Ken MacLeod and authors of the Orion's Arm Universe, have written works set in posthuman futures.
A variation on the posthuman theme is the notion of a "posthuman god"; the idea that posthumans, being no longer confined to the parameters of human nature, might grow physically and mentally so powerful as to appear possibly god-like by present-day human standards. This notion should not be interpreted as being related to the idea portrayed in some science fiction that a sufficiently advanced species may "ascend" to a higher plane of existence—rather, it merely means that some posthuman beings may become so exceedingly intelligent and technologically sophisticated that their behaviour would not possibly be comprehensible to modern humans, purely by reason of their limited intelligence and imagination. The difference here is that the latter stays within the bounds of the laws of the material universe, while the former exceeds them by going beyond it.
- Haraway, Donna J, "Situated Knowledges" in Simians, Cyborgs, and Women. Routledge, New York: 1991
- Full text of the Cyborg Manifesto
- Haraway, Donna J, Simians, Cyborgs, and Women. Routledge, New York: 1991. "A Cyborg Manifesto" originally appeared in Socialist Review in 1985.
- Hayles, N. Katherine (1999). How We Became Posthuman: Virtual Bodies in Cybernetics, Literature, and Informatics. University Of Chicago Press. ISBN 0-226-32146-0.
- World Transhumanist Association (2002–2005). "The transhumanist FAQ". Retrieved 2006-08-27.
- Warwick, K: “I,Cyborg”, University of Illinois Press, 2004
- Deborah Christie, Sarah Juliet Lauro, ed. (2011). Better Off Dead: The Evolution of the Zombie as Post-Human. Fordham Univ Press. p. 169. ISBN 0-8232-3447-9, 9780823234479
- Orion's Arm - Encyclopedia Galactica - Archailects
- Michael Shermer. Shermer's Last Law, Jan 2002
- Nichols, Steve (1988). "The Posthuman Manifesto (originally published 1988 UK)."
- Dixon, Dougal (1990). Man After Man: An Anthropology of the Future.
- Pepperell, Robert (1995). The Posthuman Condition: Consciousness beyond the brain.
- Rahimi, Sadeq (2000). Identities without a Reference: Towards a Theory of Posthuman Identity., M/C: A Journal of Media and Culture , Vol. 3, No. 3, June 2000.
- Nedkova, Iliyana; Byrne, Chris. (2004) Designer Bodies: Towards the Posthuman Condition, Art Research Communication.
- (French) Babin, Dominique (2004). PH1. Manuel d'usage et d'entretien du post-humain. Flammarion. (review in The Future Fire 1).
- Bostrom, Nick.(2005) In Defence of Posthuman Dignity, Bioethics, Vol. 19, No. 3, pp. 202–214. doi:10.1111/j.1467-8519.2005.00437.x
- Nalesnik, Daniel (2005). "Posthumanity: Changing Our Species."
- (French) Serge Venturini (2007). Éclats d’une poétique du devenir post-humain, 2000-2007, (Livre II), Éditions L'Harmattan, coll. « Poètes des cinq continents », Paris, 2007 ISBN 978-2-296-03301-6. 
- Elhefnawy, Nader (2007) Nikolai Fedorov and the Dawn of the Posthuman in The Future Fire.
- Seidel, Asher (2008). Inhuman Thoughts: Philosophical Explorations of Posthumanity. Review by C. L'Hôte, Ph.D. in Metapsychology, Jan 6th 2009.
- Hiller, James P. (2010). A Superluminal Transmission, Short Story.
- Ferrando, Francesca (2012). Humans, Cyborgs, Posthumans, TED (conference).