Economist Robin Hanson did not invent the Great Filter

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Humanity seems to have a bright future, i.e., a non-trivial chance of expanding to fill the universe with lasting life. But the fact that space near us seems dead now tells us that any given piece of dead matter faces an astronomically low chance of begating (sic) such a future. There thus exists a great filter between death and expanding lasting life, and humanity faces the ominous question: how far along this filter are we? Robin Hanson, 1996 or 1998

During the Cold War, it was a commonplace that we might make ourselves extinct or end industrial civilization. After all, humans were lighting navigable rivers on fire, producing mountains of waste with no good plans to dispose of it, and putting weapons more terrible than the Sun into hands with the self-control of an ornery chimpanzee. It seemed very plausible that the Third World War might start, some junior officer would drop a nuclear warhead on an armoured division in Bavaria or Thuringia, and a few days later there would be mushroom clouds over every city in the Northern Hemisphere with more than 10,000 people. The main thing to debate was whether some remote parts of the world might survive more or less intact to repopulate the Northern Hemisphere (Brazil, South Africa, and New Zealand were among the more realistic choices). Science fiction fans extended this idea to other hypothetical civilizations and suggested that any species like humans would be in danger of starting devastating wars just as it became capable of reaching space. Let’s look at some examples:

In 1963, Fred Saberhagen wrote the first story featuring the Berserkers, self-reproducing artificial intelligences programmed to destroy all life. The Berserkers have eliminated all intelligent life in the Milky Way which they have encountered (including their creators) until they encounter humanity. The very next story in the same issue of Worlds of If has a throwaway paragraph about “A galaxywide game, played for planets, using local cultures. And always according to the rules. No new technologies. No new weapons. Use what you have at hand. Play it fair. Because if you do not, neither will we — and together we will eliminate the universe.” (Gary Wright, “Captain of the Kali,” Worlds of If (January 1963), p. 113 archive.org / isfdb). The main debate among worldbuilders at the time was whether the future would be cyclical rises and falls (Asimov’s Foundation, Piper’s Future History) or a choice between galactic expansion and destruction. In Saberhagen’s setting, almost all spacefaring civilizations are annihilated by Berserkers, but not every civilization builds its own Berserkers.
In 1972, Freeman Dyson gave a talk at the Institute for Advanced Study where he warned that unleashing robotic von Neumann probes or comets laden with trees (!) across the galaxy could end badly. Reporters recorded part of it as follows: “I have a feeling we’re going to discover things that are not so pleasant, particularly since the activities we’re likely to discover first are highly technological activities. We’re more likely to discover first the species in which technology has gone out of control, a technological cancer spreading throughout the galaxy. We should be suitably scared if we discover it, and take our precautions.” (Israel Shenkers, Will Galaxy Reveal a Technological Cancer? A Physicist Wonders, The New York Times 27 Nov 1972 p. 37) Dyson did not say that this was the most likely outcome, but that humans were more likely to notice alien technology which was reproducing out of control than technology which quietly grabbed a few small asteroids or comets and scooped some gas from Saturn. This talk was alluded to by futurists interested in John von Neumann’s robotic probes.
Carl Sagan’s Cosmos (1980 TV series with accompanying book) contains a rhapsody imagining aliens receiving radio transmissions from Earth. “There was our region of the galaxy; there was our world. I had found the entry for earth: HUMANITY: THIRD FROM THE SUN. They had heard our television broadcasts and thought them an application for cosmic citizenship. Our technology had been growing enormously (they got that right). Two hundred nation states, about six global powers, the potential to become one planet. Probability of survival over a century — here, also, less than one percent.” Sagan postulated that if a species developed nuclear weapons, it would probably wipe itself out, and imagined alien scientists estimating humanity’s chance of survival based on observing many civilizations.

With more time I could add many more examples of science fiction which uses aliens to talk about the Cold War and the possibility that humanity or industrialized civilization would annihilate itself, such as Piper’s First Cycle from around 1960 or Murray Leinster’s “Second Landing” from 1954. Most of these do not explicitly say that destruction is the most likely outcome, because they were written for people who understand subtext and can generalize. A science-fiction story is not an academic treatise, but ideas flow back and forth between science fiction and academic futurism.

In 1996 or 1998 a PhD student named Robin Hanson called this the Great Filter. He acknowledged that this idea was not new:

A devastation scenario is implicit in the usual formulation of the Drake equation. For prior evolutionary steps the equation asks for the probability that the system will reach the next step, but at our level of evolution, the equation asks for the expected time until the civilization disappears, and once gone it is assumed to never return. … I personally think that most of the Great Filter is most likely to be explained by the steps I think we understand the least about: the steps in the biological evolution of life and intelligence. However, many physical scientists focus on explaining the filter via the area they seem to think we understand the least: social science. Astronomers Sagan and Newman, for example, claim that either we will destroy ourselves with nuclear weapons, or learn to “live with other groups in mutual respect” by losing “our own predispositions to territoriality and aggression. … This adaptation must apply … with very high precision, to … every individual within the civilization”, so that we become the “least likely to engage in aggressive galactic imperialism” [Sagan & Newman]. Similarly, Papagiannis claims that “those that manage to overcome their innate tendencies toward continuous material growth and replace them with non-material goals will be the only ones to survive this crisis,” implying a galaxy “populated by stable highly ethical and spiritual civilizations” [Papagiannis 84]. And Stephenson claims that “for a truly advanced intelligence the drive for quality rather than redundant quantity would be paramount” [Stephenson 82].

The early Internet was scholarly, and it was hard not to know in 1996 that many educated people thought humanity had almost extinguished itself or civilization had almost ended itself. So Robin Hanson naturally cited earlier versions of his idea. However, time passed, and people got distracted from nuclear war by other dangers. Hanson and his friends like Eric Drexler and Toby Ord are still around and promoting themselves, while writers from the 1960s and 1970s are not. And so I meet people online, and read Wikipedia pages, which say things like “The concept originates in Robin Hanson’s argument …”

This is clearly incorrect. The idea that a civilization able to build radios and travel into space would likely destroy itself was common in the 1960s and 1970s, and featured in an extremely popular TV series in 1980. Therefore, the idea existed long before Robin Hanson gave it a catchy name in 1996 or 1998.

I am not as amusing as those old science-fiction writers and futurists, and I would much prefer to be writing about ancient roads and medieval doublets. But someone was wrong on the internet, and dreams of yesterday’s tomorrows seem more important than zombie ideas about ancient Greek cleavers. If you can, please support this site. If not, continue as I point to some other context for Hanson’s ideas.

What we have forgotten and what we have learned

Hanson’s post has some curious ideas, like the idea that a “bright future” for humanity requires filling the universe with life, and perhaps disassembling Jupiter or Sol for spare parts. When he shared it, I think most readers ignored them and went back to arguing about whether Captain Picard could beat Darth Vader or which operating system to use. This was a mistake, just as the magazine article a few years earlier which called some similar ideas the California Ideology. His ideas came from places much older than California, and some of them could first be found in monasteries not think-tanks.

Sagan and Hanson and Hanson’s disciples like to contrast light with darkness. That is theological language out of Zoroastrianism via Jewish and Christian thought. If you tell yourself that all that matters is whether eternity is filled with life and light or death and darkness, you can screw yourself to the sticking point and do terrible things to actually existing human beings today. Elsewhere Hanson envisions a future of countless simulated humans working themselves to exhaustion for a bare minimum subsistence while biological humans live in luxury (The Age of Em, 2016), and in 2023 he was still concerned about fertility decline even though the world population was the highest it had ever been and still growing. The same righteousness that comes out of dualistic theology is the righteousness that might let someone launch the A-bombs or unleash the Berserkers. Words have power and these are dangerous visions.

I am a scholar of ancient Iran, not of apocalyptic religions. I don’t want to explore all the places that Hanson’s ‘s ideas come from here. But for now, I will leave you with two questions. If you think that expanding across the universe is the most sacred of all causes, and machines seem better suited to doing that than humans, do you really love life? And what if the interests of life as we know it clash with what would be required to launch that first von Neumann probe? Bertolt Brecht saw what happens when men who love ideas more than people find that the ideas lose their stark beauty when human beings are ordered to carry them out.

Wäre es da / Nicht doch einfacher, der Philosoph / Löste Menschheit auf und / Schäfte etwas neues?

Economist Robin Hanson did not invent the Great Filter

What we have forgotten and what we have learned

Further Reading