Our cat raised the issue when it came into the room at breakfast time. It jumped as we did at the clatter of a dropped pan, then walked calmly round a chair in its way. Was our cat conscious or intelligent, or both?
All the evidence points to intelligence and consciousness being seen as different properties that are intimately, even inevitably, bonded now, because we homo sapiens theorise about the two ideas and felines don't. It's not a case, as Descartes proposed, of 'I think therefore I am', but rather one of 'I am, therefore I think'.
Everyone shares some of the ability of an Einstein to feel and experience the world while lacking any ability to conceive and address the problems he saw in it. Many forms of life must have been, and still are, 'conscious' in that sense - able to exist and persist without thinking about it - but not intelligent in our human meaning of the word.
What we call consciousness comes first as a principle of life. Over time that has developed into the exquisitely responsive state we term intelligence, that mirrors its vastly more complex environment today.
Any difference between the two, as so often, lies only in the way we use words. Consciousness and intelligence are inseparable, if not the same thing, distinguishable only because our evolved minds think and speak of them that way.
