Consciousness is still a big mystery, and I've always wondered what causes it. I've decided that it is most likely one of two possibilities: that consciousness is "simple," or "complex." 1) If consciousness is simple, then that means that it is simply an inherent property of the universe. Imagine your consciousness if you did not have a brain: you wouldn't be able to see, hear, or even think. You would be dead in all ways, however there would still be an "awareness" present, aware of the nothingness that it is experiencing. If consciousness is simple, then that "empty awareness" exists just as fundamentally as space, time, and particles. If an organ evolves that is capable of feeling any kind of sensation, then the empty awareness would "pick up" the senses. This would mean that even an organism with no brain can still feel, and have a subjective experience (although it obviously can't think). It would also mean that everything subconscious is still happening consciously, just not communicating with the consciousness of your brain. Your leg, while you are asleep, will still consciously feel the pain of being bitten by a mosquito. But since that information isn't communicated to your brain, "your" consciousness doesn't pick it up. 2) The second way consciousness could operate would be through complexity. If this is the case, then consciousness is a sort of program running on your brain, just like all of the other "programs" that contain your information and behavior. This would mean that consciousness is 100% physical, which brings about some paradoxical thinking. Think of the "Star Trek teleporter" situation. A machine records exactly all of your physical information, destroys you, and reconstructs you. Is that "you?" If consciousness is complex and thus a result of physical matter, then an exact copy of you should be exactly "you." What happens if the original you isn't destroyed, and a copy is still made? Do you experience being in both of these vessels at the same time, but your two minds just can't communicate with each other? Some might argue that their brains would soon become different because they would have different experiences, and thus they would have different consciousnesses (since consciousness is a product of physical matter, if it is indeed complex). But wouldn't that mean that every time you have an experience, you die and are replaced by a new consciousness? This question can be asked another way. Suppose someone created an artificial organ that could feel pain, but with no brain attached to it. The organ receiving the pain would be structured exactly like any part of a human body that can feel pain. The question is, would there be something there to experience that pain, (although it wouldn't know that pain is "bad," having no brain) or would the subjective experience of pain not exist for that organ? Yet a simpler way of asking the question is to ask: is a brain required to have a subjective experience, or does anything that "feels" in any way automatically have a subjective experience?? Hopefully I made this coherent enough to understand. It is hard for me to put these concepts into words. Please let me know if anything needs to be clarified.