Thomas Nagel’s definition of consciousness
Whenever we can describe the experience of a different life as “it’s like____”, it means that that thing is experiencing consciousness. That is, if we feel comfortable posing the question "what’s it like to be a bat?", and we believe that there is some sense of experience when talking about what it’s like to be a bat, then by our definition, a bat experiences consciousness.
- This definition of consciousness is as opposed to words that may seem like synonyms, like attentiveness, reportability, mere access etc.