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SF Themes

Eleven Themes

HG Wells pioneered time travel, space travel, alien invasion, future history and invisibility.
Other writers address telepathy, teleportation and immortality.
Isaac Asimov appropriated robots and the idea of an applicable science of society.
(His future history incorporates time travel and "psychohistory", the science of society, and presents an immortal space-travelling telepathic robot.)
Robert Heinlein's future history introduced the "generation ship" (multi-generation interstellar spaceship) idea.


Interviewed on British radio, Asimov described robots as "mobile computers". However, brains are conscious of their environments and linguistic brains are additionally conscious of meanings whereas computers merely manipulate symbols according to rules and thus are conscious neither of an environment nor of the meanings of the symbols. Asimov's robots have artificial linguistic brains, therefore are not computers.

Asimov formulated Laws of Robotics, then subverted them for story purposes. Pre-Asimov robots were Menace or Pathos. Asimov's were Engineering. But he returned to Menace in "That Thou Art Mindful Of Him", to Pathos in "The Bicentennial Man" and to both in "Robot Dreams" where the robot who dreams suddenly becomes both threat and victim. He says, "I was that man," and is destroyed. (1) I discuss human-robot interactions and interpretations of the Laws in two articles here and here.

I have never seen Otto Binder's earlier I, Robot although I have been told that it is a series that does not develop. Asimov's I, Robot begins with a household servant, continues with several experimental robots and culminates when a humanoid robot (possibly) holds elected office and also when giant robot Brains control the global economy for the good of humanity in accordance with First Law. "Robots as Menace" returns in a later collection when the Brains, regarding self-determination as the greatest human good, have phased themselves out but have been succeeded by the Georges who, programmed to prioritise obedience to the ablest, most intelligent human beings, come to disregard the difference between flesh and metal and therefore to regard themselves as the human beings who should be obeyed in accordance with the Second Law of Robotics, now Humanics.

If, like most, though not all, of Asimov's robot stories, "That Thou Art Mindful Of Him" is incorporated into his future history, then we know that the later history contains not a robotic dictatorship but secret guidance of historical processes by the benign humanoid Robot Daneel Olivaw who, concealing his robotic nature because human beings would reject help from an artefact, plans to transform humanity into a telepathic collective whose "good" will be single, concrete and easier to achieve. Because men programmed robots to value human beings, Daneel now persuades humanity to value itself. Asimov simplified history but was a master of dialectics, the interpenetration of opposites. We have come a long way from Robby the faithful servant to Daneel the benevolent manipulator and Asimov would probably have taken us further if he had lived longer.

Immortality etc

Several future histories incorporate immortality. Robert Heinlein's Future History introduced the generation ship idea and revealed that an immortal man had lived right through the History - and, before that, through the twentieth century in which we lived while reading the series. Poul Anderson's first future history, modelled on Heinlein's, addressed Heinleinian themes (a generation ship and an immortality that becomes pointless because it requires total isolation) and Asimovian themes (an unemployed robot and an applied social science that prevents mutiny in the generation ship but fails to prevent revolution on Earth).

In James Blish's Okies history, antiagathics make generation ships unnecessary and preserve some interstellar nomads until the end of the universe. In Anderson's The Boat Of A Million Years, a few immortal mutants live through recorded history into an indefinite future but I prefer Anderson's treatment of artificial immortality in World Without Stars. In Larry Niven's A World Out Of Time, chemicals associated with ageing are teleported out of the body. Thus, immortality meets teleportation and the instant elsewhere is the young forever.

My point here is that sf resembles an extended seminar with authors presenting innovative deductions from shared premises. I briefly discuss immortality in fantasy and sf in "Immortality" here.


In Superman versus Aliens, an alien is teleported from inside Superman's body. One X Man is a teleport. In Kenneth Bulmer's Behold The Stars, aliens at war with Earth sabotage interstellar matter transmitters so that Earthmen arrive without the will to fight. In Anderson's The Enemy Stars, fuel is teleported to interstellar spaceships and crews teleport between Earth and the ships. One of Heinlein's Scribner Juveniles, Tunnel In The Sky, features interstellar teleportation instead of the usual faster than light spacecraft. In Star Trek, "transporters" make scenes with shuttle craft unnecessary. Alfred Bester's Tiger! Tiger! presents a society in which most people can teleport.


Wells' Invisible Man was, like Mr Hyde, a pre-comics super-villain. Invisibility has become a comic book super power (see "Comics and Science Fiction" here) and occurs in CS Lewis' juvenile fantasy, The Chronicles of Narnia.


Anderson's character Dominic Flandry learns how to lie to a telepath. Blish presents four different scientific rationales for telepathy. In Heinlein's Scribner Juvenile, Time For The Stars, the confirmed instantaneity of telepathy between twins on Earth and in an interstellar spaceship facilitates the development of instantaneous spacecraft. Bester's The Demolished Man describes a telepathic society. Telepathy is big in Olaf Stapledon's works, discussed below. In CS Lewis' "The Shoddy Lands", Lewis as character enters another character's consciousness. I have heard of but not read other major works on telepathy. Readers of this article will fill the gaps.

Future Histories

A British future history is a fictitious historical text book whereas an American future history is a series of stories and novels set in successive periods. Olaf Stapledon recounts Martian invasions and Neptunian colonisation but as a historian, not as a novelist, whereas Robert Heinlein's Future History includes a story about financing the first Moon landing and a novel about the Second American Revolution. American future histories can be constructed either "inclusively" or "exclusively". See "American Future Histories" here and "CS Lewis and James Blish" here.

Future histories develop. Wells covers a single period and historical turning point whereas Stapledon covers the entire future. In A Short History of the Future, the little known RC Churchill combines narratives from Orwell, Huxley, Bradbury, Vonnegut etc. Anderson's Psychotechnic History imitated Heinlein's Future History  but Anderson later constructed his Technic History by linking two existing series. Larry Niven and Jerry Pournelle are later successors of Heinlein. In Anderson's Tales of the Flying Mountains, extra-solar colonists discuss how to teach their earlier history among the asteroids to their children. Anderson's Harvest of Stars future history covers human-AI interaction. His Genesis covers post-human, aiming to become post-cosmic, AI. In Galaxies like Grains of Sand, Brian Aldiss synthesises the British and American approaches by linking short stories with historical passages. In Genesis, Anderson synthesises the two approaches by alternating chapters of action and dialogue with chapters on Stapledonian timescales.

Four Wellsian Themes

In "CS Lewis and James Blish", I argue that:

(i) Wells' The Time Machine, The First Men in the Moon, The War of the Worlds and The Shape of Things to Come pioneered time travel, space travel, alien invasion and future history, respectively;
(ii) following Wells, Olaf Stapledon's Last and First Men incorporates these themes and opens a tetralogy also covering past history (Last Men in London), cosmic history (Star Maker) and a contemporary evolutionary advance (Odd John);
iii) replying to Wells and Stapledon, Lewis' Ransom Trilogy covers an interplanetary journey, a demonic invasion of a sinless planet and demonic manipulation of a Wellsian plan for the future of humanity;
(iv) like The Time Machine, Lewis' unfinished Ransom novel, "The Dark Tower", begins with a group discussion of the possibility or otherwise of time travel;
(v) thus, four works by Lewis parallel four by Wells;
(vi) following Wells and referencing Lewis, James Blish's theological trilogy, After Such Knowledge (ASK), addresses past and future science and present demons;
(vii) like Ransom, Blish's character Adolph Haertel travels to Mars in the juvenile novel, Welcome to Mars;
viii) also like Ransom, Haertel's successors travel to a sinless planet in ASK Volume III, A Case of Conscience;
(ix) like Ransom's adversaries, other Blish characters invoke and converse with demons in ASK Volume IIa, Black Easter;
(x) thus, three Blish works, including one and a half volumes of ASK, parallel Ransom;
(xi) however, Blish's Mars is scientifically accurate, his sinless planet is Godless and his demons are victorious;
(xii) thus, his informal post-Lewis trilogy is also an antithesis;
(xiii) Blish disagreed with Lewis' beliefs but respected his insights and admired his novels whereas the later writer, Philip Pullman, is not post- but anti-Lewis;
(xiv) however, Pullman's juvenile trilogy, His Dark Materials, is fantasy, not sf, and replies to Narnia, not to Ransom.

Thus, sixteen works by Wells, Stapledon, Lewis and Blish, though not by Pullman, form a conceptual sequence addressing philosophical and moral issues through sf themes. (Two related works are the earlier, unfinished version of The Time Machine, "The Chronic Argonauts", which introduces the circular causality paradox, and the earlier, unfinished version of Star Maker, Nebula Maker, which covers pre-stellar nebular history.) Wells and Stapledon present an anthropocentric alternative to Biblical-Dantean-Miltonic metaphysics. Lewis re-affirms the latter. Blish defends science, though without advocating a Wellsian scientific restructuring of society. He writes ambiguously about the supernatural in ASK Volume I, Doctor Mirabilis, and Volume III, A Case of Conscience, but imagines it as real in Volume II, Black Easter/The Day After Judgement.

These four writers reflect on man's cosmic role by showing men interacting with extraterrestrial races. Lewis alone presents such races as "unFallen" although Blish addresses this issue ambiguously in ASK III. Wellsian and Stapledonian Martians invade Earth. Stapledonian Terrestrials invade Venus and Neptune. A Lewisian demon infests Venus by possessing a space travelling scientist. Thus, Lewis subverts the alien invasion idea for theological purposes. His Ransom Volume II, Perelandra, also, though less obviously, replies to Star Maker because Ransom's Christian vision of creation contrasts with Stapledon's revelation of an aesthetically motivated but morally indifferent creator.

Although Blish's alien invasion novel, VOR, is not part of this conceptual sequence, his A Case of Conscience definitely parallels Perelandra by describing Earthmen arguing on a sinless planet. Despite this summary, the differences between Lewis' and Blish's novels are greater than their similarities. Lewis' humanly habitable sinless planet is Venus whereas Blish's is extra-solar. Lewis' Venerians are green but humanoid and immortal because unFallen whereas Blish's Lithians are reptilian and, of course, mortal. Lewis' Christian character, like Lewis an Anglican layman, fantastically confronts unequivocal evil whereas Blish's Christian character, unlike Blish a Jesuit priest, more plausibly contends with colleagues who have different points of view.

The Time Machine, The Shape of Things to Come, Last and First Men and Ransom Volume III, That Hideous Strength, all address the human future. Will humanity devolve, degenerate or remake itself? Does it need a supernatural salvation? To this second question, the Biblical tradition answers yes, Wells and Stapledon answered no, Lewis answered yes and Blish was agnostic. The other sf futures mentioned above, anthropocentric, robotic or AI-dominated, would also be unacceptable to Lewis who would find demons concealed in the technology of any society that was not theocentric.

That Hideous Strength, although not a future history, is about the future and is specifically a reply to The Shape of Things to Come and to Last and First Men. Lewis mentions Stapledon in the Preface and parodies Wells (as "Jules") in the text. Written during the war, published at the end of the war and set after the war, the novel dramatises two alternative futures for Britain and the world. Wells and Stapledon had thought that mankind would be able to remake itself with science. Lewis replied that any supposed remaking would in fact be a technological dictatorship destroying humanity and even allowing demonic control (!) His invocation of an Arthurian past is not irrelevant but is part of his response to a Wellsian future. Black Easter, although not a reflection on the future, does end with apparent demonic control and is in memoriam CS Lewis.

In Julian May's Pliocene Exile/Intervention/Galactic Milieu sequence (one tetralogy and one trilogy with one intermediate volume):

many people become telepathic;
a few also become immortal;
one character reads Odd John;
a benign extraterrestrial intervention changes society;
a few terrestrials flee to the Pliocene only to meet malign alien invaders then;
the trilogy covers a short period of future history;
a Pliocene exile surviving until the Galactic Milieu influences the events that led to his exile;
Catholic and extraterrestrial characters present a post-Lewisian cosmic theology.

May's sequence addresses Wellsian and other sf themes and Christian theology, refers to Odd John and echoes Blish with the term "Okies" although used in a different sense. Thus, May's eight volumes can be added to the sixteen earlier volumes of this conceptual sequence which now has three British authors and two American of whom the first, Blish, moved to Britain (which may not prove much but is an interesting observation).

The four Wellsian themes also provide a template for comparing other authors' works. Most sf is post-Wellsian but not also post-Lewisian, including Blish's time travel story, "The City That Was The World", his interplanetary novel, Welcome to Mars, his alien invasion novel, VOR, and his future history, Cities in Flight. Welcome to Mars fits into the above mentioned sequence first because, as a journey to Mars story, it parallels Ransom Volume I, Out of the Silent Planet, secondly because, as hard sf, it is antithetical to Lewis' theological/mythological approach and thirdly because, although not part of ASK, it is a prequel to ASK III.

Heinlein wrote three first man on the Moon stories: his Future History version, his Scribner Juvenile version and a film version. He also wrote an alien invasion novel, The Puppet Masters, three classic statements of the time travel circular causality paradox, the original American Future History and, arguably also, a Juvenile Future History because five early Scribner Juveniles share background references with each other and with the "Green Hills of Earth" period of the (adult) Future History.

Larry Niven combined first man on the Moon with time travel in "Wrong Way Street". Logically, a future lunar explorer who finds an alien time machine and travels into the past while remaining on the Moon thus becomes the first man on the Moon. Niven addressed alien invasion with Jerry Pournelle in Footfall and is still writing a major future history. Poul Anderson wrote eight future histories, six volumes on time travel covering both circular causality and causality violation, including the sacred texts of the Time Patrol, a novel in which a time dilated spaceship outlasts the universe and a short story in which militarily superior humanoid aliens sell their services to the highest bidding terrestrial government, thus conquering Earth economically. Again, the premises are familiar but not always the conclusions.

Time Travel 

Because time time travel distorts the order of events, it is difficult to write about. An astronaut who will travel to Mars has not yet arrived on Mars whereas a chrononaut who will travel to the eleventh century arrived in the eleventh century a thousand years ago. A ten year round trip to Mars equals a ten year absence from Earth whereas, if a chrononaut who has spent ten years in the eleventh century returns to his departure point, then he loses no time in his home era. If history books do not record a chrononaut's activities in 1918, then they will not start to record such activities after he has departed to 1918. These points may seem simple but conversation about them is not.

A fellow sf fan once argued that, since we do not know how time travel would work, it is pointless to argue about how sf writers present it. However, we do know whether a conclusion follows from a premise. If the Enterprise crew have travelled from the twenty second to the twentieth century without loss of memory, then it cannot be assumed later in the same script that, if a man is returned to an earlier time, then he automatically forgets everything that he has experienced since that time. Writers reasoning consistently from stated premises would improve the quality of time travel fiction. See "The Logic of Time Travel" here.


Listing themes helps us to classify and compare sf works. Such classifications and comparisons can be extremely comprehensive but never complete.

(Added Feb 2012: In There Will Be Time, Poul Anderson linked time travel to the generation ship idea in a way that I had thought of but was not able to write a book about: if time travellers enter a generation ship before it leaves Earth, travel future-wards within the ship, visit its destination, then return past-wards within the ship, then they can report the outcome of the mission before its departure.

(In his Martian Trilogy, Michael Moorcock linked time travel to interplanetary adventure. Edgar Rice Burrough's character John Carter had astrally travelled to a humanly inhabited Mars. Moorcock, pastiching Burroughs but also knowing that Mars is not humanly inhabited, made his character Michael Kane time travel to Mars at a time when it was inhabited, before humanity had migrated from Mars to Earth.) 

1. Asimov, Isaac. Robot Dreams, Ace Books, 1986.


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