I love Carl Sagan. He had a childlike wonder for the vastness of space and time, but sort of glossed over important things like freewill and consciousness. I think it was Sagan that first said something like, 'we're all made of stardust'. Pretty cool concept. And, even though the atoms that make up my body were once the waste product of some star, I'd like to know how these lifeless atoms became consciousness.
First off, maybe I'm asking the wrong question. My question presumes that there is such a thing as consciousness, so we could attack this problem by simply denying the existence of consciousness. There are several ways to do this. For example, you could claim that so many things are conscious, that the term becomes meaningless. After all, isn't the 7-eleven gas pump "conscious" of my credit card entering the little swipe gap, and so forth and so on? Well, this form of attack is slightly dishonest, as most of us should be able to agree that the one thing we know "for certain" is our own consciousness. Now, I can't speak for you--you may be a robot or some sort of trickery--but I know what "I am". I am conscious. Ok, so there's at least one vast collection of stardust that is officially conscious.
By the way, if all we really know for sure is that "I AM', this leads me even further off topic. When Moses was talking to God, he was curious as to God's name. A reasonable request, because maybe Moses was talking to an alien, or someone from another dimension, or who knows what. If I was talking to some scary strange voice, I would probably first wet myself (just being honest), and second, ask "Who are you? What are you?" I love the response found in Exodus 3:14: "Now they may say to me, 'What is His name?' What shall I say to them?" 14 God said to Moses, "I AM WHO I AM"; and He said, "Thus you shall say to the sons of Israel, 'I AM has sent me to you.'" Does a name get any better than I Am? (Maybe this name was some sort of hint as to the essence of God)
Back to the task at hand. We start with some lifeless stuff. Atoms. We end up with consciousness. Can evolutionary biology tell us how consciousness got here? Well, we all know there was a big bang, then bacteria, then billions of years of natural selection, then "I am". From a purely scientific viewpoint, why should atoms bother to organize into a conscious being? Seems pretty pointless. Sure, you can find my personal opinion in the New Testament, but it would be interesting to hear a purely physical explanation for the existence of consciousness.