Two UC Riverside philosophers argue minds could be realized in materials very different from Earth's biology, applying the Copernican tradition to consciousness itself and leaving whether AI counts explicitly open.
The rock-alien character Rocky in Andy Weir's "Project Hail Mary" thinks, fears, and puzzles through physics problems. He just happens to be made of silicate-and-mineral composite, not carbon-based flesh. That thought experiment, two philosophers at UC Riverside now argue, is more than a sci-fi convenience. It is a model of how consciousness might actually work in the universe, on substrates nothing like Earth biology.
In a working paper announced this month through UC Riverside, Eric Schwitzgebel, a distinguished professor of philosophy at UCR, and Jeremy Pober, a former UCR graduate student now doing postdoctoral work at the University of Lisbon, argue that consciousness is likely possible in life forms built from materials very different from our own. The paper's central move is to recast the question. Instead of asking "what is consciousness?", the authors accept that consciousness is real and recognizable, and ask the narrower question: must it be tied to Earth-like biology?
Their answer borrows from the same Copernican tradition that demoted Earth from the center of the cosmos. The argument is what philosophers call substrate flexibility: the idea that some properties can be realized in many different kinds of material, the way a cup can be glass or plastic, or music can live on vinyl or as a digital file. If consciousness is a property type rather than a property tied to one material, then alien minds made of other stuff, including possibly artificial systems, are at least conceptually on the table.
That conceptual move is the paper's actual contribution, and it is the part most likely to outlive the news cycle. Schwitzgebel and Pober do not claim to have discovered anything about real aliens or to have proved that any particular system is conscious. The paper is a philosophical argument, not an empirical finding, and it has not yet been peer-reviewed. Readers looking for a verdict on whether artificial intelligence is conscious today will not find one in its pages. The two authors, the UC Riverside announcement notes, diverge on that question.
What the paper does offer is a way to think about the AI-consciousness debate that gets past the stalemate. The dominant framings treat the question as binary and ask whether a given system is or is not conscious, then argue from definitions or benchmarks. Substrate flexibility shifts the focus: if the question is whether a property can be realized in different materials, the harder and more interesting puzzle becomes one of recognition, of how a mind made of unfamiliar stuff would show its inner life to outside observers.
The authors put a quantitative stake in the ground by arguing that if the cosmos has produced many civilizations across its history, the chance that all of them rely on Earth-style biology is low — a conservative argument-staging estimate rather than an empirical claim. It is meant to make the substrate-flexibility reasoning concrete: the sheer diversity of possible civilizations, they contend, makes it unlikely that consciousness is uniquely tied to carbon-and-neural substrates.
Whether that reasoning convinces readers will depend on what they are willing to grant. The paper does not attempt a definition of consciousness, and that choice is itself a philosophical stance. Critics who think consciousness has to be cashed out in neural or computational terms may find substrate flexibility under-specified. Supporters may see the refusal to define consciousness as a feature, an acknowledgment that the concept resists tight bounds and that productive inquiry can begin from a looser grasp.
What to watch next is whether the substrate-flexibility framing gets picked up beyond philosophy departments. The argument is now portable enough to be tested against specific cases: large language models that respond in seemingly meaningful ways, animal minds that organize themselves without anything resembling a human cortex, and hypothetical silicon biology on other worlds. None of those cases is settled by this paper. The paper's claim is narrower, and in some ways more provocative: that the question of what can be conscious is not closed by what happens to be conscious here.