What is light before we see it?
For Berkeley, everything that has not been perceived doesn't exist, but light needs to exist unperceived before it reaches the eyes. How is this possible in Berkeley's idealism?
Considering that light is an object, and the observer is the subject, what Berkley means is:
light needs to exist unperceived before it reaches the eyes.
Light needs to exist unperceived before it reaches the eyes. Berkeley's position would have to be that since nothing can exist without being perceived, light not only does not need to exist unperceived; it cannot do so. To start from basics :
On Berkeley's account, all that exist are minds or spirits and their ideas. Light is improbably a mind or spirit; we may assume, then, that it is an idea.
To set out an argument :
All that exist are minds or spirits and their ideas.
Light is not a mind or spirit.
Light exists and is therefore an idea.
My ideas of sense (i.e. those which I have when I perceive objective states of affairs) come into my mind without being caused to do so by any act of my will.
Light is such an idea.
The occurrence of any idea must be caused by the will of some being in whose mind the idea occurs.
My ideas of sense are in the mind of, and caused by the will of, some being other than myself.
Therefore my idea of light, or light as an idea, is caused by the will of some being other than myself.
That being is God. (From Berkeleian assumption that my ideas of sense are caused by God.)
Therefore whenever light exists it exists as an idea in the mind of God, who causes my and others' idea of light.
Therefore whenever light exists, it exists as perceived as an idea by God and, when God causes it to do so, as an idea in my own mind.
It never exists unperceived.
Modifcation of Jonathan Bennett, 'Berkeley and God', Philosophy, Vol. 40, No. 153 (Jul., 1965), pp. 207-221: 208. (Bennett is clearly not responsible for my additions to his argument.)