Can Animals Feel? A New Roadmap for Understanding Consciousness

A New Decision Tree Brings Clarity to the Animal Consciousness Debate

What does it mean for an animal to be conscious? This age-old question is more than a philosophical musing—it has tangible impacts on how we treat animals in research, wildlife management, and everyday life. Recently, a philosophy scholar at Michigan State University has developed a practical tool to guide scientists and ethicists through this complex territory: a decision tree for evaluating animal consciousness. This structured framework may be instrumental in shaping future animal welfare policies and scientific research.

The High-Stakes Debate Over Animal Consciousness

Why does it matter if we know whether fish feel pain, or if ants experience alarm? The answer reaches beyond curiosity and into the realms of ethics and law. Granting or denying consciousness to an animal can determine whether it deserves protections, influences how we study it, and shapes conservation priorities. The scientific and philosophical debates have ranged from asking if only our close relatives—such as chimpanzees and dolphins—are conscious, to speculations about the inner lives of crabs, insects, and even plants.

“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,” says Jonah Branding, the Michigan State University researcher behind the new framework. “In the 1990s, there was serious debate over whether chimpanzees are conscious. Today, there is serious debate over whether plants are conscious.”

Markers of Consciousness: What Are They?

The crux of the debate often comes down to markers—observable traits in animals that scientists associate with consciousness. These can include certain regions in the nervous system, complex behaviors, or advanced cognitive skills. If an animal demonstrates enough of these markers, many researchers are comfortable inferring that it likely has some kind of mental experience. But what if, like many crabs or insects, an animal shows few or none of the commonly accepted markers? This is where the controversy sharpens.

Branding’s contribution was to clarify these muddy waters by dividing thinkers into two philosophical camps:

Symmetry Approach: This camp insists on clear, positive evidence. If an organism has enough recognized markers, it’s likely conscious. If it doesn’t, the presumption is that it’s not.
Asymmetry Approach: Here, scholars warn that the absence of evidence isn’t evidence of absence. Just because we lack markers for consciousness in a given animal, we can’t definitively claim it has no consciousness at all.

Branding identified these competing views as central to many scientific deadlocks. His decision tree doesn’t take sides but offers a logical structure for figuring out where we stand and why.

The Decision Tree: How Does It Work?

Branding’s tree acts like a flowchart, guiding users through questions about how markers of consciousness are identified. Are they rooted in theory, analogy (comparing species), or function? Depending on the answers, someone could be steered toward the symmetry or asymmetry view.

Central to the tree is the case of creatures like hermit crabs. While they lack some of the neural complexity seen in mammals, their behaviors—choosing and even swapping shells depending on their needs and environment—demonstrate a sophistication that challenges the notion of them as mere stimulus-response machines. Branding’s tree helps researchers decide whether these capacities are enough to warrant a judgment of consciousness—or whether we should reserve judgment in cases of uncertainty.

Why It Matters: Practical Implications for Science and Ethics

The implications of Branding’s work extend far beyond academic debate. The way we define and detect consciousness influences lab animal protocols, conservation priorities, food production regulations, and moral consideration for diverse species.

Creatures who are recognized as feeling pain or having emotional experiences may warrant humane treatment and protective legislation. Meanwhile, misclassifying animals as entirely unconscious could lead to unnecessary suffering. The decision tree doesn’t provide final answers but frames the debate so that future research and policy can be more consistent and logically defensible.

Kristin Andrews, a leading thinker in the field who was not involved in the study, hailed the approach as a much-needed roadmap for navigating endlessly tangled arguments. “Branding offers a road map to help us answer some of the most difficult questions about which beings are conscious,” she says.

The Road Ahead: More Questions, Better Answers

Branding’s decision tree won’t immediately resolve whether insects feel emotion or if slugs experience anything as they roam the forest floor. Yet it provides a tool for mapping our assumptions about consciousness, guiding more transparent ethical and scientific decision-making.

As testing and understanding the markers of consciousness improves, this framework will help ensure our conclusions are built on clear, rational grounds. Instead of arguing past one another, scientists and philosophers can now identify exactly where their conceptual differences lie and find common ground—or at least, shared ways to refine their disagreements.

Ultimately, the hope is that—with more nuanced reasoning—both the creatures we share the planet with and the policies that govern their treatment will benefit.