Streamlining the consciousness debate, from trees to hermit crabs

(Press-News.org) Beyond spirited dinner party debate, establishing which creatures have consciousness matters in terms of animal welfare and conservation policy. A Michigan State University philosophy scholar has added clarity to a messy philosophical debate.

In this month’s journal Biology & Philosophy, PhD candidate Jonah Branding contributes a decision tree that can be applied to questions such as, do fish feel pain when they’re on a hook? Does an ant feel alarm when protecting its colony? Do banana slugs feel anything when they eat dead leaves on the forest floor? Or are these simpler organisms more like stimulus-response machines, which don’t have any mental experience?

“There has been a lot of work on the question of animal consciousness in recent years and claims about consciousness are starting to be taken seriously for more and more organisms,” Branding said. “In the 1990s, there was serious debate over whether chimpanzees are conscious. Today, there is serious debate over whether plants are conscious.”

Acknowledging that creatures have feelings, thoughts and/or a first-person perspective is messy. In the paper “Can a marker approach exclude?” Branding sets some order to different approaches to ethical, scientific, and philosophical questions.

"Consciousness science is notorious for its twists and turns,” said Kristin Andrews, professor of philosophy at City University of New York and York Research Chair in Animal Minds. “In his paper, Branding offers a road map to help us answer some of the most difficult questions about which beings are conscious."

Andrews who is not involved in the study, was an original signer of the 2024 New York Declaration on Animal Consciousness.

Branding works with markers - observable features of organisms that are thought to correlate with consciousness. They can include specific brain regions, patterns of complex behavior, or sophisticated cognitive capacities. If an animal has a lot of the right kinds of markers, the animal is probably conscious.

But what if an animal shows few or no markers? Branding breaks beliefs about that into two groups. On the side is what he calls symmetry, which is those who need evidence – a right number of markers.  If the creature falls short, it’s not a conscious being.

Those who believe markers are evidence of consciousness but say that an absence of markers doesn’t prove against consciousness are in the asymmetry camp.

Branding, a member of MSU’s Ecology, Evolution, and Behavior Program, nails this as the sticky widget of the disagreement and tries to untangle it by asking what it is about that missing marker that is so important in the first place. He creates a decision tree to help narrow down the questions.

He invites considering the hermit crab. Crabs fail in a lot of markers – lacking sizable brains and generally lousy at showing those sophisticated cognitive capacities. But those crabs select their own shell houses, and when confronted with a maze, they’ve been known to swap out shells to better navigate.

“I argue that, depending on which of these approaches you start with, and what you think about a few other related issues in the field, we can figure out where you should fall on the question of exclusion,” Branding said, adding that the questions help parse out how beings in the natural world should be valued and treated.

 “These are questions of how we interact with the world,” he said. “There are major ethical implications about who we have to care about morally.”

END