I have always admired Nicholas Humphrey's perspectives on sensing and consciousness, and referenced his ideas on evolution of the nervous system in my Biology of Mind book. He has now written a nice essay in Seed Magazine, and I strongly recommend that you read it. He argues against the idea:
...that consciousness must be helping us do something that we can do only by virtue of being conscious, in the way that, say, a bird can fly only because it has wings, or you can understand this sentence only because you know English.Rather,
...I want to suggest the role of phenomenal consciousness may not be like this at all. Its role may not be to enable us to do something we could not do otherwise, but rather to encourage us to do something we would not do otherwise: to make us take an interest in things that otherwise would not interest us, or to mind things we otherwise would not mind, or to set ourselves goals we otherwise would not set.
I will not hold back from telling you my own main conclusion from a lifetime's interest in what consciousness does. I may shock you by what may seem the naivety of my conclusion (I've shocked myself): I think the plain and simple fact is that consciousness—on various levels—makes life more worth living.
We like being phenomenally conscious. We like the world in which we're phenomenally conscious. We like ourselves for being phenomenally conscious. And the resulting joie de vivre, the enchantment with the world we live in, and the enhanced sense of our own metaphysical importance have, in the course of evolutionary history, turned our lives around.
Added note 11/16/08: I just found a later published version of this article. PDF here.