Imagine a world in which there is no thought.
In such a world, there would not be humans. There would be biological machines, carrying and vocalizing the label “human”, but they would not know they were. For knowing requires thought. There would not be actions, calculated or otherwise. There would be reactions, intricate chemical processes, subsystems interacting with each other in predetermined ways, the only true cause for any effect.
How can we be so sure that isn’t our world? How can we say consciousness isn’t a canvas being projected onto, but part of the interface of control? Every process in our body brought forth by signals of some kind, machinery operating itself. Claiming to be able to control the weather, something so much larger than us, would be absurd. Then why is it we view controlling ourselves, a cohesion of reactions so much smaller than us, as something perfectly normal?
Observers, controllers, or illusions. We can’t possibly tell.