What makes a mind powerful—indeed, what makes a mind conscious—is not what it is made of, or how big it is, but what it can do. Can it concentrate? Can it be distracted? Can it recall earlier events? Can it keep track of several different things at once? Which features of its own current activities can it notice or monitor? When such questions as these are answered, we will know everything we need to know about those minds in order to answer the morally important questions. These answers will capture everything we want to know about the concept of consciousness, except the idea of whether, as one author has recently said, “the mental lights would be out” in such a creature. But that is just a bad idea—in spite of its popularity. (...) For suppose that we have answered all the other questions about the mind of some creature, and now some philosophers claim that we still don’t know the answer to that all-important question, Is the mental light on—yes or no? Why would either answer be important? We are owed an answer to this question, before we need to take their question seriously.
Daniel Dennet, Kinds of Minds