What is it like to be a bat?” asks the philosopher Thomas Nagel in the title of a famous essay.
We cannot know that because we are locked into an external perspective in our observation.
We may know a lot about a bat's cognitive abilities.
But we have no idea how it feels to navigate using echolocation.
It is about the concept of qualia, the subjective experience of a mental state, the phenomenal consciousness.
The term consciousness has different meanings in everyday language.
We sometimes mean heightened alertness, controlled perception as opposed to unfocused or unconscious perception, sometimes alertness as opposed to mental absence, sleep or unconsciousness.
Unfortunately, there is no scientifically strict and uniform definition of the term, philosophy, psychology or neuroscience each emphasize different aspects.
For example, neuroscientist António Damásio defines consciousness as a state of mind in which one is aware of one's own existence and the existence of an environment.
We deal with consciousness as a phenomenon of experience.