In debates about consciousness, one of the most frequently asked questions goes something like this: “What is it about consciousness that helps us survive? Why couldn’t we have had all this cognitive apparatus but simply been machines that don’t feel anything or have any experience?” As I hear it, this question is basically asking, “Why did consciousness get added on to brains that reached a certain level of complexity? Why was consciousness thrown into the bargain as a kind of bonus? What extra evolutionary good does the possession of consciousness contribute, if any?”

To ask this question is to make the tacit assumption that there could be brains of any desired level of complexity that are not conscious. It is to buy into the distinction between Machines Q and Z sitting side by side on the old oaken table in Room 641, carrying out identical operations but one of them doing so with feeling and the other doing so without feeling. It assumes that consciousness is some kind of orderable “extra feature” that some models, even the fanciest ones, might or might not have, much as a fancy car can be ordered with or without a DVD player or a power moonroof.

— I Am a Strange Loop by Douglas R. Hofstadter