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The future of humanity is often viewed as a topic for idle speculation. Yet our beliefs and assumptions on this subject matter shape decisions in both our personal lives and public policy – decisions that have very real and sometimes unfortunate consequences. It is therefore practically important to try to develop a realistic mode of futuristic thought about big picture questions for humanity. This paper sketches an overview of some recent attempts in this direction, and it offers a brief discussion of four families of scenarios for humanity’s future: extinction, recurrent collapse, plateau, and posthumanity.
The future of humanity as an inescapable topic
In one sense, the future of humanity comprises everything that will ever happen to any human being, including what you will have for breakfast next Thursday and all the scientific discoveries that will be made next year. In that sense, it is hardly reasonable to think of the future of humanity as a topic: it is too big and too diverse to be addressed as a whole in a single essay, monograph, or even 100-volume book series. It is made into a topic by way of abstraction. We abstract from details and short-term fluctuations and developments that affect only some limited aspect of our lives. A discussion about the future of humanity is about how the important fundamental features of the human condition may change or remain constant in the long run.
What features of the human condition are fundamental and important? On this there can be reasonable disagreement. Nonetheless, some features qualify by almost any standard. For example, whether and when Earth-originating life will go extinct, whether it will colonize the galaxy, whether human biology will be fundamentally transformed to make us posthuman, whether machine intelligence will surpass biological intelligence, whether population size will explode, and whether quality of life will radically improve or deteriorate: these are all important fundamental questions about the future of humanity. Less fundamental questions – for instance, about methodologies or specific technology projections – are also relevant insofar as they inform our views about more fundamental parameters.
Traditionally, the future of humanity has been a topic for theology. All the major religions have teachings about the ultimate destiny of humanity or the end of the world.1 Eschatological themes have also been explored by big-name philosophers such as Hegel, Kant, and Marx. In more recent times the literary genre of science fiction has continued the tradition. Very often, the future has served as a projection screen for our hopes and fears; or as a stage setting for dramatic entertainment, morality tales, or satire of tendencies in contemporary society; or as a banner for ideological mobilization. It is relatively rare for humanity’s future to be taken seriously as a subject matter on which it is important to try to have factually correct beliefs. There is nothing wrong with exploiting the symbolic and literary affordances of an unknown future, just as there is nothing wrong with fantasizing about imaginary countries populated by dragons and wizards. Yet it is important to attempt (as best we can) to distinguish futuristic scenarios put forward for their symbolic significance or entertainment value from speculations that are meant to be evaluated on the basis of literal plausibility. Only the latter form of “realistic” futuristic thought will be considered in this paper.
We need realistic pictures of what the future might bring in order to make sound decisions. Increasingly, we need realistic pictures not only of our personal or local near-term futures, but also of remoter global futures. Because of our expanded technological powers, some human activities now have significant global impacts. The scale of human social organization has also grown, creating new opportunities for coordination and action, and there are many institutions and individuals who either do consider, or claim to consider, or ought to consider, possible long-term global impacts of their actions. Climate change, national and international security, economic development, nuclear waste disposal, biodiversity, natural resource conservation, population policy, and scientific and technological research funding are examples of policy areas that involve long time-horizons. Arguments in these areas often rely on implicit assumptions about the future of humanity. By making these assumptions explicit, and subjecting them to critical analysis, it might be possible to address some of the big challenges for humanity in a more well-considered and thoughtful manner.
The fact that we “need” realistic pictures of the future does not entail that we can have them. Predictions about future technical and social developments are notoriously unreliable – to an extent that have lead some to propose that we do away with prediction altogether in our planning and preparation for the future. Yet while the methodological problems of such forecasting are certainly very significant, the extreme view that we can or should do away with prediction altogether is misguided.
1 (Hughes 2007)
That view is expressed, to take one example, in a recent paper on the societal implications of nanotechnology by Michael Crow and Daniel Sarewitz, in which they argue that the issue of predictability is “irrelevant”:
preparation for the future obviously does not require accurate prediction; rather, it requires a foundation of knowledge upon which to base action, a capacity to learn from experience, close attention to what is going on in the present, and healthy and resilient institutions that can effectively respond or adapt to change in a timely manner.2
Note that each of the elements Crow and Sarewitz mention as required for the preparation for the future relies in some way on accurate prediction. A capacity to learn from experience is not useful for preparing for the future unless we can correctly assume (predict) that the lessons we derive from the past will be applicable to future situations. Close attention to what is going on in the present is likewise futile unless we can assume that what is going on in the present will reveal stable trends or otherwise shed light on what is likely to happen next. It also requires non-trivial prediction to figure out what kind of institution will prove healthy, resilient, and effective in responding or adapting to future changes.
The reality is that predictability is a matter of degree, and different aspects of the future are predictable with varying degrees of reliability and precision.3
It may often be a good idea to develop plans that are flexible and to pursue policies that are robust under a wide range of contingencies. In some cases, it also makes sense to adopt a reactive approach that relies on adapting quickly to changing circumstances rather than pursuing any detailed long-term plan or explicit agenda. Yet these coping strategies are only one part of the solution. Another part is to work to improve the accuracy of our beliefs about the future (including the accuracy of conditional predictions of the form “if x is done, y will result”). There might be traps that we are walking towards that we could only avoid falling into by means of foresight. There are also opportunities that we could reach much sooner if we could see them farther in advance. And in a strict sense, prediction is always necessary for meaningful decision-making.4
2 (Crow and Sarewitz 2001)
3 For example, it is likely that computers will become faster, materials will become stronger, and medicine will cure more diseases; cf. (Drexler 2003).
4 You lift the glass to your mouth because you predict that drinking will quench your thirst; you avoid stepping in front of a speeding car because you predict that a collision will hurt you.
Predictability does not necessarily fall off with temporal distance. It may be highly unpredictable where a traveler will be one hour after the start of her journey, yet predictable that after five hours she will be at her destination. The very long-term future of humanity may be relatively easy to predict, being a matter amenable to study by the natural sciences, particularly cosmology (physical eschatology). And for there to be a degree of predictability, it is not necessary that it be possible to identify one specific scenario as what will definitely happen.
If there is at least some scenario that can be ruled out, that is also a degree of predictability. Even short of this, if there is some basis for assigning different probabilities
(in the sense of credences, degrees of belief) to different propositions about logically possible future events, or some basis for criticizing some such probability distributions as less rationally defensible or reasonable than others, then again there is a degree of predictability. And this is surely the case with regard to many aspects of the future of humanity.
While our knowledge is insufficient to narrow down the space of possibilities to one broadly outlined future for humanity, we do know of many relevant arguments and considerations which in combination impose significant constraints on what a plausible view of the future could look like. The future of humanity need not be a topic on which all assumptions are entirely arbitrary and anything goes. There is a vast gulf between knowing exactly what will happen and having absolutely no clue about what will happen. Our actual epistemic location is some offshore place in that gulf.5
Technology, growth, and directionality
Most differences between our lives and the lives of our hunter-gatherer forebears are ultimately tied to technology, especially if we understand “technology” in its broadest sense, to include not only gadgets and machines but also techniques, processes, and institutions. In this wide sense we could say that technology is the sum total of instrumentally useful culturally-transmissible information. Language is a technology in this sense, along with tractors, machine guns, sorting algorithms, double-entry bookkeeping, and Robert’s Rules of Order.6
Technological innovation is the main driver of long-term economic growth. Over long time scales, the compound effects of even modest average annual growth are profound. Technological change is in large part responsible for many of the secular trends in such basic parameters of the human condition as the size of the world population, life expectancy, education levels, material standards of living, and the nature of work, communication, health care, war, and the effects of human activities on the natural environment. Other aspects of society and our individual lives are also influenced by technology in many direct and indirect ways, including governance, entertainment, human relationships, and our views on morality, mind, matter, and our own human nature. One does not have to embrace any strong form of technological determinism to recognize that technological capability – through its complex interactions with individuals, institutions, cultures, and environment – is a key determinant of the ground rules within which the games of human civilization get played out.7
5 For more on technology and uncertainty, see (Bostrom 2007b).
6 I’m cutting myself some verbal slack. On the proposed terminology, a particular physical object such as farmer Bob’s tractor is not, strictly speaking, technology but rather a technological artifact, which depends on and embodies technology-as-information. The individual tractor is physical capital. The transmissible information needed to produce tractors is technology.
7 See e.g. (Wright 1999).
This view of the important role of technology is consistent with large variations and fluctuations in deployment of technology in different times and parts of the world. The view is also consistent with technological development itself being dependent on socio-cultural, economic, or personalistic enabling factors.
The view is also consistent with denying any strong version of inevitability of the particular growth pattern observed in human history. One might hold, for example, that in a “re-run” of human history, the timing and location of the Industrial Revolution might have been very different, or that there might not have been any such revolution at all but rather, say, a slow and steady trickle of invention.
One might even hold that there are important bifurcation points in technological development at which history could take either path with quite different results in what kinds of technological systems developed. Nevertheless, under the assumption that technological development continues on a broad front, one might expect that in the long run, most of the important basic capabilities that could be obtained through some possible technology, will in fact be obtained through technology. A bolder version of this idea could be formulated as follows:
Technological Completion Conjecture. If scientific and technological development efforts do not effectively cease, then all important basic capabilities that could be obtained through some possible technology will be obtained.
The conjecture is not tautological. It would be false if there is some possible basic capability that could be obtained through some technology which, while possible in the sense of being consistent with physical laws and material constraints, is so difficult to develop that it would remain beyond reach even after an indefinitely prolonged development effort.
Another way in which the conjecture could be false is if some important capability can only be achieved through some possible technology which, while it could have been developed, will not in fact ever be developed even though scientific and technological development efforts continue.
The conjecture expresses the idea that which important basic capabilities are eventually attained does not depend on the paths taken by scientific and technological research in the short term. The principle allows that we might attain some capabilities sooner if, for example, we direct research funding one way rather than another; but it maintains that provided our general techno-scientific enterprise continues, even the non-prioritized capabilities will eventually be obtained, either through some indirect technological route, or when general advancements in instrumentation and understanding have made the originally neglected direct technological route so easy that even a tiny effort will succeed in developing the technology in question.8
8 For a visual analogy, picture a box with large but finite volume, representing the space of basic capabilities that could be obtained through some possible technology. Imagine sand being poured into this box, representing research effort. The way in which you pour the sand will determine the places and speed at which piles build up in the box. Yet if you keep pouring, eventually the whole space gets filled.
One might find the thrust of this underlying idea plausible without being persuaded that the Technological Completion Conjecture is strictly true, and in that case, one may explore what exceptions there might be. Alternatively, one might accept the conjecture but believe that its antecedent is false, i.e. that scientific and technological development efforts will at some point effectively cease (before the enterprise is complete). But if one accepts both the conjecture and its antecedent, what are the implications? What will be the results if,
in the long run, all of the important basic capabilities that could be obtained through some possible technology are in fact obtained? The answer may depend on the order in which technologies are developed, the social, legal, and cultural frameworks within which they are deployed, the choices of individuals and institutions, and other factors, including chance events. The obtainment of a basic capability does not imply that the capability will be used in a particular way or even that it will be used at all.
These factors determining the uses and impacts of potential basic capabilities are often hard to predict. What might be somewhat more foreseeable is which important basic capabilities will eventually be attained. For under the assumption that the Technological Completion Conjecture and its antecedent are true, the capabilities that will eventually be include all the ones that could be obtained through some possible technology. While we may not be able to foresee all possible technologies, we can foresee many possible technologies, including some that that are currently infeasible; and we can show that these anticipated possible technologies would provide a large range of new important basic capabilities.
One way to foresee possible future technologies is through what Eric Drexler has termed “theoretical applied science”.9 Theoretical applied science studies the properties of possible physical systems, including ones that cannot yet be built, using methods such as computer simulation and derivation from established physical laws.10 Theoretical applied science will not in every instance deliver a definitive and uncontroversial yes-or-no answer to questions about the feasibility of some imaginable technology, but it is arguably the best method we have for answering such questions. Theoretical applied science – both in its more rigorous and its more speculative applications – is therefore an important methodological tool for thinking about the future of technology and, a fortiori, one key determinant of the future of humanity.
9 (Drexler 1992)
10 Theoretical applied science might also study potential pathways to the technology that would enable the construction of the systems in questions, that is, how in principle one could solve the bootstrap problem of how to get from here to there.
It may be tempting to refer to the expansion of technological capacities as “progress”. But this term has evaluative connotations – of things getting better – and it is far from a conceptual truth that expansion of technological capabilities makes things go better. Even if empirically we find that such an association has held in the past (no doubt with many big exceptions), we should not uncritically assume that the association will always continue to hold. It is preferable, therefore, to use a more neutral term, such as “technological development”, to denote the historical trend of accumulating technological capability.
Technological development has provided human history with a kind of directionality. Instrumentally useful information has tended to accumulate from generation to generation, so that each new generation has begun from a different and technologically more advanced starting point than its predecessor. One can point to exceptions to this trend, regions that have stagnated or even regressed for extended periods of time. Yet looking at human history from our contemporary vantage point, the macro-pattern is unmistakable.
It was not always so. Technological development for most of human history was so slow as to be indiscernible. When technological development was that slow, it could only have been detected by comparing how levels of technological capability differed over large spans of time. Yet the data needed for such comparisons – detailed historical accounts, archeological excavations with carbon dating, and so forth – were unavailable until fairly recently, as Robert Heilbroner explains:
At the very apex of the first stratified societies, dynastic dreams were dreamt and visions of triumph or ruin entertained; but there is no mention in the papyri and cuniform tablets on which these hopes and fears were recorded that they envisaged, in the slightest degree, changes in the material conditions of the great masses, or for that matter, of the ruling class itself.11
Heilbroner argued in Visions of the Future for the bold thesis that humanity’s perceptions of the shape of things to come has gone through exactly three phases since the first appearance of Homo sapiens. In the first phase, which comprises all of human prehistory and most of history, the worldly future was envisaged – with very few exceptions – as changeless in its material, technological, and economic conditions. In the second phase, lasting roughly from the beginning of the eighteenth century until the second half of the twentieth, worldly expectations in the industrialized world changed to incorporate the belief that the hitherto untamable forces of nature could be controlled through the appliance of science and rationality, and the future became a great beckoning prospect. The third phase – mostly post-war but overlapping with the second phase – sees the future in a more ambivalent light: as dominated by impersonal forces, as disruptive, hazardous, and foreboding as well as promising.
Supposing that some perceptive observer in the past had noticed some instance of directionality – be it a technological, cultural, or social trend – the question would have remained whether the detected directionality was a global feature or a mere local pattern. In a cyclical view of history, for example, there can be long stretches of steady cumulative development of technology or other factors. Within a period, there is clear directionality; yet each flood of growth is followed by an ebb of decay, returning things to where they stood at the beginning of the cycle. Strong local directionality is thus compatible with the view that, globally, history moves in circles and never really gets anywhere. If the periodicity is assumed to go on forever, a form of eternal recurrence would follow.
Modern Westerners who are accustomed to viewing history as directional pattern of development may not appreciate how natural the cyclical view of history once seemed.12
11 (Heilbroner 1995), p. 8
12 The cyclical pattern is prominent in dharmic religions. The ancient Mayans held a cyclical view, as did many in ancient Greece. In the more recent Western tradition, the thought of eternal recurrence is most strongly associated with Nietzsche’s philosophy, but the idea has been explored by numerous thinkers and is a common trope in popular culture
Any closed system with only a finite number of possible states must either settle down into one state and remain in that one state forever, or else cycle back through states in which it has already been. In other words, a closed finite state system must either become static or else start repeating itself. If we assume that the system has already been around for an eternity, then this eventual outcome must already have come about; i.e., the system is already either stuck or is cycling through states in which it has been before.
The proviso that the system has only a finite number of states may not be as significant as it seems, for even a system that has an infinite number of possible states may only have finitely many proviso.13
For many practical purposes, it may not matter much whether the current state of the world has already occurred an infinite number of times, or whether an infinite number of states have previously occurred each of which is merely imperceptibly different from the present state.14
Either way, we could characterize the situation as one of eternal recurrence – the extreme case of a cyclical history.
In the actual world, the cyclical view is false because the world had a beginning a finite time ago. The human species has existed for a mere two hundred thousand years or so, and this is far from enough time for it to have experienced all possible conditions and permutations of which the system of humans and their environment is capable.
More fundamentally, the reason why the cyclical view is false is that the universe itself has existed for only a finite amount of time.15 The universe started with the Big Bang an estimated 13.7 billion years ago, in a low-entropy state. The history of the universe has its own directionality: an ineluctable increase in entropy. During its process of entropy increase, the universe has progressed through a sequence of distinct stages. In the eventful first three seconds, a number of transitions occurred, including probably a period of inflation, reheating, and symmetry breaking. These were followed, later, by nucleosynthesis, expansion, cooling, and formation of galaxies, stars, and planets, including Earth (circa 4.5 billion years ago). The oldest undisputed fossils are about 3.5 billion years old, but there is some evidence that life already existed 3.7 billion years ago and possibly earlier. Evolution of more complex organisms was a slow process. It took some 1.8 billion years for eukaryotic life to evolve from prokaryotes, and another 1.4 billion years before the first multicellular organisms arose. From the beginning of the Cambrian period (some 542 million years ago), “important developments” began happening at a faster pace, but still enormously slowly by human standards. Homo habilis – our first “human-like ancestors” – evolved some 2 million years ago; Homo sapiens 100,000 years ago. The agricultural revolution began in the Fertile Crescent of the Middle East 10,000 years ago, and the rest is history.
13 The proviso of closed system may also not have seemed significant. The universe is a closed system. The universe may not be a finite state system, but any finite part of the universe may permit of only finitely many different configurations, or finitely many perceptibly different configurations, allowing a kind of recurrence argument. In the actual case, an analogous result may hold with regard to spatial rather than temporal repetition. If we are living in a “Big World” then all possible human observations are in fact made by some observer (in fact, by infinitely many observers); see (Bostrom 2002c).
14 It could matter if one accepted the “Unification” thesis. For a definition of this thesis, and an argument against it, see (Bostrom 2006).
15 According to the consensus model; but for a dissenting view, see e.g. (Steinhardt and Turok 2002).
The size of the human population, which was about 5 million when we were living as hunter-gatherers 10,000 years ago, had grown to about 200 million by the year 1; it reached one billion in 1835 AD; and today over 6.6 billion human beings are breathing on this planet.16 From the time of the industrial revolution, perceptive individuals living in developed countries have noticed significant technological change within their lifetimes.
All techno-hype aside, it is striking how recent many of the events are that define what we take to be the modern human condition.
If compress the time scale such that the Earth formed one year ago, then Homo sapiens evolved less than 12 minutes ago, agriculture began a little over one minute ago, the Industrial Revolution took place less than 2 seconds ago, the electronic computer was invented 0.4 seconds ago, and the Internet less than 0.1 seconds ago – in the blink of an eye.
Almost all the volume of the universe is ultra-high vacuum, and almost all of the tiny material specks in this vacuum are so hot or so cold, so dense or so dilute, as to be utterly inhospitable to organic life. Spatially as well as temporally, our situation is an anomaly.17
16 (Bureau 2007). There is considerable uncertainty about the numbers especially for the earlier dates.
17 Does anything interesting follow from this observation? Well, it is connected to a number of issues that do matter a great deal to work on the future of humanity – issues like observation selection theory and the Fermi paradox; cmp. (Bostrom 2002a).
Given the technocentric perspective adopted here, and in light of our incomplete but substantial knowledge of human history and its place in the universe, how might we structure our expectations of things to come? The remainder of this paper will outline four families of scenarios for humanity’s future:
• Recurrent collapse