In a 2026 paper, Professor Eric Schwitzgebel of the University of California, Riverside, and researcher Jeremy Pober of the University of Lisbon argue that consciousness can emerge in a wide variety of physical substrates, rather than being limited to Earth's carbon-based biochemistry. The authors introduce the concept of "substrate flexibility" and draw on astrobiological estimates, suggesting that roughly a thousand behaviorally complex species could exist or have existed in the universe, while the number of potentially habitable planets may reach one quintillion.
This argument directly challenges biological naturalism, which posits that consciousness requires the specific chemical makeup found on Earth. If complex behaviors—such as communication, goal-setting, and cooperation—can be realized in silicon, sulfur, or other systems, then there is no fundamental reason to limit the phenomenon of internal experience to Earth's vertebrates, cephalopods, and certain insects. The authors refer to this as the "Copernican principle of consciousness": Earth holds no privileged position in space nor on the map of potential hosts for experience.
The study's methodology is purely philosophical and probabilistic. It lacks experimental data, neuroimaging, or behavioral tests; instead, the conclusions rest on the assumption that evolution in different environments—such as the sulfuric acid clouds of Venus—would likely result in alternative chemical foundations for life.
The most significant counterargument is that behavioral complexity does not guarantee phenomenal consciousness: functional equivalence is not identical to the presence of subjective experience. The authors themselves acknowledge that current computer chips are not inherently considered conscious unless specific evidence suggests otherwise.
The concept is most clearly illustrated by an analogy with computing devices: the same logical operation can be performed by vacuum tubes, transistors, or quantum elements—the substrate changes, yet the result remains the same. Similarly, if complex behavior and internal causality can emerge within a non-biological substrate, then tying consciousness exclusively to terrestrial tissue loses its universality.
The paper does not claim that current artificial intelligence is already conscious, nor does it propose empirical criteria for detecting it. It merely removes the a priori prohibition against non-biological substrates, thereby expanding the scope of potential research—from future exoplanet missions to the philosophical analysis of silicon-based systems.
