What is it that makes a life valuable? A popular view is that life’s moral worth depends in some way on its relationship to consciousness or subjective experience. But a practical application of this view requires the ability to test for consciousness, which is currently lacking. Here, we examine how theories of consciousness (ToC) can help do so, focusing especially on difficult cases where the answer is not clear (e.g. fetuses, nonhuman animals, unresponsive brain-injured patients, and advanced artificial systems). We consider five major ToC and what predictions they offer: Information Integration Theory, Higher-Order Thought Theory, Recurrent Processing Theory, Global Neuronal Workspace Theory, and Attention Schema Theory. We highlight the important distinction between the capacity and potential for consciousness and use it to explore the limitations in our ability to draw firm conclusions regarding an entity's consciousness on the basis of each theory.

© 2023 The Author(s). Published by Elsevier Ltd.