Language and Consciousness
Human beings' ability to speak has changed consciousness in several ways. Whereas a dog learns principally from its own experience, we can share our subjective experiences with each other and so learn from each other. We can build up a body of collective knowledge that can be passed down from one generation to another.
Not only do we use speech to talk to each other, we can talk to ourselves, inside our own minds: we can think in words. Of all the significant developments that came from language thinking has been the most important.
Words can conjure up associations to past experiences. The word "dolphin" brings back to mind images of dolphins we have seen, dogs we may have known, dolphins we have heard about, things we know about dolphins, and a range of other associations. Through words we can deliberately bring the past back to mind, independently of what is happening in the present. Other creatures may well experience associations to past experiences -- dogs seem to remember people who have treated them badly -- but their associations are almost certainly determined by what is going on around them in the present moment.
Through thinking we can liberate ourselves from this constraint.
Not only can we think about past experiences, we can entertain thoughts about the future. We can make plans and and take decisions, and exercise far greater influence over our future that other creatures. Just our consciousness has expanded in space to encompass even the edges of the Universe, so too it it has expanded in time.
Thinking has allowed us to ask questions -- "How?" and "Why?" -- and ponder their solutions. Such quests led to science and philosophy -- literally, "knowledge" and "the love of wisdom". Our consciousness discovered a whole new realm -- understanding. We could look into the heart of matter.
Self Awareness
Thinking also allows us to think about our conscious experience. We are aware not only of the many aspects and qualities of our consciousness, but also of the fact that we are conscious. We are aware that we are aware -- conscious of the faculty of consciousness.
As we observe our own inner experience, we feel there must be an experiencer, a self who is having all these experiences, making all these decisions, and thinking these thoughts.
We have used language to label just about everything else in our world of experience, so it seems a natural step to give this self, whatever it was, a label. We called it "I".
But what was this self? What was it like? Where could it be?
The Scottish philosopher David Hume spent considerable time looking within, trying to find something that was his own true self. But all he found were various thoughts, sensations, images and feelings.
The reason he never found the self was that he was looking in the wrong place; he was looking in the realm of experience, in the contents of consciousness. But the self, by definition, cannot be another content of consciousness. It is that which experiences the contents of consciousness.
The only other possibility is that this sense of self has something to do with the faculty of consciousness itself. But if that is the self we are inwardly sensing, it is not an individual, personal self. It is not a self that has any characteristics or qualities. It is not something that can be perceived or known, as we perceive and know other things. It is not a unique self. It is something we all share.