For the rainbow experience to happen we need sunshine, raindrops, and a spectator. It is not that the sun and the raindrops cease to exist if there is no one there to see them. . . But unless someone is present at a particular point no colored arch can appear. The rainbow is hence a process requiring various elements, one of which happens to be an instrument of sense perception. It doesn’t exist whole and separate in the world nor does it exist as an acquired image in the head separated from what is perceived (the view held by the “internalists” who account for the majority of neuroscientists); rather, consciousness is spread between sunlight, raindrops, and visual cortex, creating a unique, transitory new whole, the rainbow experience. Or again: the viewer doesn’t see the world; he is part of a world process.
Everything we see, hear, touch, taste, and smell, Riccardo Manzotti argues, involves the same creation of a physical unity—the moment of consciousness—sustained by processes within and without the head. The room, or part of a room, that you see now, including the screen on which you’re reading this blog, becomes, in combination with your faculties, a whole; this is consciousness. It happens in time, and it takes time (consciousness of visual phenomena seems to require at least 100 milliseconds to occur), and it changes constantly.
This minimal time lapse (some claim it is as much as 500 milliseconds) required for brain and world to generate consciousness allows Manzotti to deal with what would seem to be the obvious objection to the externalist theory. Do we not have consciousness when the eyes are shut and the mind lies in silence? And what about dreams? Isn’t the brain evidently sufficient to sustain consciousness without support from outside?
We do indeed have consciousness in these moments, Manzotti replies, but it is still spread out between mind and world. It may take only a fraction of a second for you to become conscious of the face appearing at your window, and then three more years before the same face surfaces in a dream, perhaps mingled with all kinds of other stimuli from elsewhere. But this doesn’t change the fact that consciousness is a coming together of brain and world: the physical process begun at the window is continuing in memory and dream. The congenitally blind, Manzotti points out, don’t dream colors because they have never encountered them. Consciousness is the mingling of mind process with the processes we call objects that are all in a state of flux, however fast or slow.