A provocative new paper suggests consciousness may not be unique to Earth and could arise in alien life forms far stranger than we can imagine.
A new philosophical paper argues that consciousness may not be exclusive to life as we know it. According to Eric Schwitzgebel, a distinguished professor of philosophy at the University of California, Riverside, there is little reason to think conscious experience depends specifically on flesh, blood, or the biology found on Earth.
Instead, Schwitzgebel and Jeremy Pober, a former UCR graduate student who is now a postdoctoral researcher at the University of Lisbon, propose that consciousness could emerge in life forms built from very different materials. Imagine the five-limbed, rock-skinned alien featured in the recent hit movie Project Hail Mary. The authors argue that such a possibility should not be dismissed simply because it differs radically from life on Earth.
Consciousness May Not Depend on Earth Like Biology
Rather than trying to define consciousness itself, Schwitzgebel and Pober begin with the assumption that consciousness is a genuine and recognizable phenomenon. They focus on a narrower question: Does consciousness require Earth-style biology, or could it arise in organisms with completely different physical makeup?
Their paper arrives as debates over artificial intelligence become increasingly intense. While some people envision conscious AI as either a breakthrough or a threat, the authors do not take a unified position on whether today’s AI systems are conscious. In fact, they disagree on that issue. However, their broader argument leaves open the possibility that consciousness could eventually emerge in artificial systems, even if current AI has not reached that point.
Central to their reasoning is the philosophical concept of “substrate flexibility.” A property is substrate flexible if it can exist in objects made from different materials. For example, a cup can be made from glass, ceramic, or plastic while still serving the same purpose. Likewise, a book can exist as printed pages or as a digital file, and records can be stored on vinyl or compact discs.
Schwitzgebel and Pober suggest consciousness belongs in the same category.
“The universe may contain minds stranger than we can imagine,” Schwitzgebel said.
Why Alien Consciousness Could Be Possible
Astronomers estimate that the observable universe contains roughly 1 trillion galaxies, and planets appear to be abundant. Most of those worlds likely have environments that look nothing like Earth’s.
To support their argument, the authors estimate that at least 1,000 behaviorally sophisticated extraterrestrial civilizations have existed somewhere in the universe. They describe this as a conservative figure, pointing out that “one recent survey found median scientific estimates over one civilization per galaxy at some point in that galaxy’s lifetime.”
Astrobiologists have also explored the possibility that life elsewhere may not rely on the same chemistry as life on Earth. Researchers have examined alternative amino acids, different solvents, and even entirely different chemical structures that might support living organisms.
Andy Weir’s novel Project Hail Mary offers one fictional example. The story features an alien with an exterior made of oxidized minerals, two circulatory systems, mercury-based blood, steam-powered muscles, and a crystal brain. It evolved on an extremely hot world with an ammonia-saturated atmosphere.
Schwitzgebel and Pober are not claiming such exotic organisms actually exist. Instead, they argue that if life can develop under a wide range of chemical conditions and the universe offers countless opportunities for evolution, it would be surprising if every successful life form relied on the exact same biochemical ingredients.
Even on Earth, evolution has produced an extraordinary variety of nervous systems. Octopuses, bees, and dogs all process information differently. The authors argue there is little reason to expect evolution elsewhere would be any less inventive.
The Copernican Principle of Consciousness
The paper builds on a familiar lesson from astronomy. Nicolaus Copernicus and later scientists demonstrated that Earth is not the center of the solar system, the solar system is not the center of the Milky Way, and the Milky Way is not the center of the universe. Over time, science has repeatedly shown that humanity occupies a less privileged position than people once believed.
Schwitzgebel and Pober suggest consciousness may follow that same pattern.
If many sophisticated alien species exist with biological systems unlike our own, they argue that it would be a form of “terrocentrism” to assume that consciousness belongs only to organisms resembling life on Earth. They call this idea the “Copernican principle of consciousness.”
That does not mean every advanced species must be conscious. Instead, they argue that if consciousness does arise in behaviorally sophisticated organisms, there is little reason to believe it would be restricted to life sharing Earth’s particular chemistry.
Throughout history, scientific discoveries have repeatedly challenged the belief that humans occupy a uniquely special place in the universe. The authors suggest consciousness may be another example.
Rather than being a rare feature limited to one type of biological machine, consciousness could emerge wherever evolution, or something similar, produces the right level of complexity.
What This Could Mean for Artificial Intelligence
The paper naturally raises questions about AI, but the authors stop well short of arguing that today’s AI systems are conscious.
Pober believes we should not assume current computer hardware is capable of supporting consciousness. In his view, recognizing that consciousness could arise in more than one physical substrate does not mean it can emerge in every possible substrate.
Schwitzgebel is somewhat more open to the possibility. He argues that once we abandon the assumption that consciousness requires human biology, it becomes more difficult to dismiss silicon-based systems simply because they are made of silicon.
He also believes discussions about AI consciousness have focused on the wrong question.
“It’s focused too much on whether silicon can duplicate a human brain and not enough on the broader question of what kinds of systems can be conscious,” he said.
The paper also distinguishes between highly specific questions and broader categories. Asking whether human consciousness can exist in another substrate is a narrow question because human consciousness may depend on many biological details unique to our species. Consciousness itself is a broader concept.
The authors compare this to flight. An eagle, hummingbird, bat, and insect all fly, but each does so in a different way. In the same way, they argue, consciousness could emerge in many different forms without necessarily resembling human consciousness.
Reference: “Substrate Flexibility and the Copernican Principle of Consciousness” by Jeremy Pober and Eric Schwitzgebel.
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