Should humans stay on Earth?

Should humans leave Earth at all? Oftentimes, particularly in communities of people who are interested in outer space, this question is given little real consideration. Of course we should leave, goes the common line of reasoning, since staying on a single planet is existentially risky. But there are also existential risks associated with leaving Earth. We spoke with Phil Torres, a scholar who studies existential threats to humanity. His works include Morality, Foresight, and Human Flourishing, The End, and A Crisis of Faith. He explains to us why “suffering catastrophe” may make leaving Earth less appealing than it first sounds.


Briefly, what is your argument that leaving Earth would cause a “suffering catastrophe”?

Many advocates of space colonization simply assume that space will be peaceful. But why should we accept this idea? What reasons are there for believing that spreading beyond Earth will usher in a new era of cooperation and prosperity? There are three mechanisms that could provide security to future species and civilizations that are spread throughout the universe.

Morality, Foresight, and Human’s Flourishing, written by Phil Torres in 2017

The first mechanism that provides security is trust. If you and I both genuinely trust that we aren’t going to attack each other, then neither you nor I have any reason to preemptively strike the other. But if you don’t completely trust me, it will be rational for you to build up some defenses just in case I strike you; if I perceive this as you preparing to attack, it will be rational for me to build up some defenses as well. The result would be a feedback loop of militarization that can lead to conflict — a phenomenon that international relations scholars call the “security dilemma.” A related concept is the “Hobbesian trap”: even if I harbor no ill will toward you, I might want to attack you simply to eliminate the possibility of you attacking me.

Now we can ask: will future species and civilizations be able to trust each other? I argue that the answer is “definitely no”. The reason is that as we spread into space, our lineage will undergo all sorts of speciation events. A colonized universe would likely contain a huge diversity of distinct creatures with completely different motivations, beliefs, desires, and worldviews, and this diversity will greatly undercut trust. If you and I are so different that you can’t figure out why I do what I do or what I actually want, this will make you nervous about being able to predict my behavior — and this is enough to lead us into a security dilemma or Hobbesian trap.

The second mechanism that provides security is what the philosopher Thomas Hobbes called a “Leviathan,” meaning the state system. In this concept, the state is something of a neutral referee that can prevent conflict from breaking out between you and me. In this case it doesn’t matter if you and I don’t trust each other because if you attack me, I know that the state will intervene to punish you and compensate me for my losses.

Now we can ask: could future species and civilizations establish a cosmic Leviathan that could act as a neutral referee to prevent conflict from breaking out? Could there be a universal governing system that imposes law and order on the cosmopolitical realm? I argue that the answer is “no”. The reason is that for a Leviathan to be effective, its law enforcement, judiciary, and other branches need to be well-coordinated for the state to effectively provide security. If you’re being robbed and you call the cops, but they don’t show up for another five days, the state will have failed to provide security. This is nothing but anarchy! The point is that given the truly vast reaches of space and the speed limit of light, a well-coordinated cosmic Leviathan would be impossible to establish. It would be ineffective and, as such, useless.

Another book written by Phil Torres – The End: What Science and Religion Tell Us about the Apocalypse

Finally, the third mechanism that provides security is a policy of deterrence: if I convince you that I’m not going to attack you, but that if you attack me, I’ll launch a retaliatory strike that is as bad or worse than your attack, this would give you a good reason not to preemptively attack me. If you convince me of the same thing, then we will have achieved a stable equilibrium that’s called a “balance of terror”. This was known as “mutually assured destruction” during the Cold War, and it played a crucial role in maintaining international peace.

Once again, we can ask: would policies of deterrence work in space? I argue that they probably wouldn’t. Consider the Cold War again. If the Soviet Union had launched a barrage of nuclear missiles at the US, the US would have seen these coming and started launching nuclear missiles back at the Soviet Union. Furthermore, until recently it was impossible to completely destroy the other side’s nuclear arsenal — in other words, each side’s nuclear arsenals were “survivable”. Consequently, even if the US didn’t immediately launch a counterstrike, it could do so later because many of its nuclear missiles would still be intact.

Phil Torres wrote A Crisis of Faith in 2012

Now compare this with the situation of a colonized universe. By the time our descendants make it into space, they will likely have offensive technologies that are far beyond what we can currently imagine. They might also have powerful defensive technologies, but the advantage will likely go to the attacker rather than defender. One reason is that, already, we have “direct-energy weapons”, such as laser guns, which can inflict damage almost instantaneously. In a future where perhaps thousands or millions or billions of civilizations have weapons like these — as well as “sun guns” and “particle beam weapons” — policies of deterrence would almost certainly break down, thus failing to provide a sufficient degree of security for civilizations to avoid a Hobbesian trap.

The conclusion, then, is that colonizing space would result in widespread, constant, catastrophic wars between future species and civilizations — in other words, a suffering catastrophe!

Do you think that this scenario is a valid argument for not pursuing space colonization?

So far, no one has provided a particularly compelling counterargument to the line of reasoning above, although perhaps there is a flaw in this reasoning that hasn’t yet been identified. More than anything, I take the moral of this argument, so to speak, to be that we should think really hard about the possible and probable consequences of venturing into space. Yes, we will need to leave Earth within a billion years if we want to survive, but why rush the process? So many times throughout history we’ve done something without seriously thinking through the potential consequences. We’re in a privileged situation right now with respect to space colonization — now is the time to think hard about whether colonizing the universe would actually be a good thing, either this century or later.

How did you come to be interested in writing about such topics?

A major inspiration for this particular project came from the international relations theorist Daniel Deudney, based at Johns Hopkins. He has a forthcoming book called Dark Skies that examines the colonization of the solar system and concludes that the outcome would almost certainly be catastrophic. My approach is more “big picture” in that I imagine a moment in the deep future when our lineage has diversified throughout the cosmos, long after we’ve made it beyond the solar system. In other words, I argue that even if we survive creating an Earth-independent civilization on Mars, we’re still not secure — nor will we (probably) ever be, given the lack of mutual trust between species, the impossibility of a well-coordinated cosmic Leviathan, and the ineffectualness of policies of deterrence.