What if consciousness has nothing to do with flesh and blood?

The possibility may sound like science fiction, but it is becoming an increasingly serious philosophical question as scientists search for alien life and artificial intelligence grows more sophisticated. A new analysis argues that consciousness may not be unique to Earth’s biology and could, in principle, emerge in life forms built from entirely different materials.

Eric Schwitzgebel, a distinguished professor of philosophy at the University of California, Riverside, and Jeremy Pober, a former UCR graduate student now a postdoctoral researcher at the University of Lisbon, contend that there is little reason to think conscious experience is tied exclusively to carbon-based life. Instead, they argue, consciousness could arise wherever evolution, or something like it, produces the right kind of complex system.

Rather than attempting to define consciousness itself, the researchers begin with the assumption that it is a real phenomenon. From there, they explore a deceptively simple question: Must consciousness depend on the biology found on Earth, or could it take forms unlike anything humanity has ever encountered?

Their paper arrives as debates over conscious artificial intelligence grow more urgent, inspiring both hopeful visions and alarming scenarios. Schwitzgebel and Pober address AI only briefly and do not offer a shared conclusion. In fact, their views differ. Still, their argument leaves room for the possibility that AI could be conscious someday, even if current systems may not be.

The central idea in the paper is “substrate flexibility.” A property is substrate flexible when it can be produced by more than one type of material. A cup, for example, can be made from glass, plastic or many other substances. A book can exist on paper or in digital form. Music can be stored on vinyl or compact discs.

Schwitzgebel and Pober argue that consciousness may work in a similar way.

“The universe may contain minds stranger than we can imagine,” Schwitzgebel said.