Alien Life Could Be Conscious in Ways Very Different From Earth, Philosophers Argue

A new philosophy paper argues that consciousness may not depend on Earth-style biology. Eric Schwitzgebel, a professor of philosophy at the University of California, Riverside, and Jeremy Pober, a former UCR graduate student now at the University of Lisbon, co-wrote it. They say there is little reason to think conscious experience requires flesh, blood or Earth biology. "The universe may contain minds stranger than we can imagine," Schwitzgebel said.

Central to their argument is "substrate flexibility" — the idea that a property can exist in things made of very different materials. A cup can be glass, ceramic or plastic and still be a cup. Amid intensifying debate over artificial intelligence, Schwitzgebel and Pober do not agree with each other on whether today's AI systems are conscious. Their argument leaves open that consciousness could arise in artificial systems someday.

To support their case, the authors note that astronomers estimate the observable universe holds roughly 1 trillion galaxies, most likely hosting planets unlike Earth. Schwitzgebel and Pober estimate at least 1,000 behaviorally sophisticated extraterrestrial civilizations have existed, a figure they call conservative. They cite a survey whose median scientific estimate was more than one civilization per galaxy over that galaxy's lifetime.

The paper's central idea is what the authors call the "Copernican principle of consciousness," based on a familiar astronomical pattern. Earth is not the center of the solar system, and the solar system is not the center of the Milky Way. The authors argue it would be "terrocentrism" to assume consciousness belongs only to Earth-like organisms, if sophisticated alien species with different biology exist. They stress that not every advanced species must be conscious.

As an illustration, the authors point to the alien in Andy Weir's novel Project Hail Mary, later adapted into a film. It is a fictional creature with an exterior of oxidized minerals, two circulatory systems and mercury-based blood. It also has steam-powered muscles and a crystal brain, and evolved on a hot, ammonia-saturated world.