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?

  • 2
    No, light does not need to exist unperceived. All that our eyes can attest to is what they perceive, and these perceptions can be created directly in them (say, by God), the rest is just speculation. See SEP for details of Berkeley's position on unperceived objects. – Conifold Aug 28 at 20:49
  • I made an edit which you are welcome to roll back or continue editing. You can see the versions by clicking on the "edited" link above. I assume God is doing whatever perceiving is needed to keep what we are not perceiving in existence in Berkeley's metaphysics. – Frank Hubeny Aug 28 at 21:07
  • Then we can conclude that a priori light does't exist, but only colors and shapes are immediately given by God? Light is just a matematical construct, an abstraction, given after the phenomenon? – Arthur Carneiro Aug 28 at 22:04
  • I think you raise a good question. I don't know the answer. One can even ask this from a quantum mechanical perspective--what is a quantum system when we are not looking at it or measuring it? Of course in Berkeley's case it is not just quantum systems but larger objects such as tables and trees. – Frank Hubeny Aug 29 at 1:18
  • With your last comment, you are "moving towards" Kant: we perceive phenomena (colors, etc.); thus, the "inferred" entities, like photons, are noumena. – Mauro ALLEGRANZA Aug 29 at 9:51

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.

  • Before being perceived by the eyes, light is not light, it is just some process or mechanism outside the subject. Like temperature is just a feeling, not an atomic property (there are no hot atoms). Like sound is just molecular bouncing and vibration until it is interpreted by the brain.
  • You talk of light as it would be an object. Does a rainbow exists as an object? It has all properties of an object, but out there, out of our bodies, mind, ideas, etc. nature is just quantum fields. Sizes, boundaries, time, space, etc. are just subjective ideas. Do you know that your head is older than your feet, and that your head exist after your feet? The idea of now is just mental. The same happens with here or this. Everything occurs and exists in our reason. But objects don't. What are the limits of that light you refer to?
  • Nothing exists unperceived. Even dark matter: we suppose it might exist because mathematically we perceive something out there that causes some things we cannot explain without it. Are there 15 planets in the solar system? No, there exist only 8, because we've perceived it. And there will exist 8 until we perceive new ones. Another example: does money exists? If you read about economy, you will learn that it doesn't. You have just a number on a computer, like you have a message on Hotmail. Money seems so real, but it's just a representation of what we (the society) owe you in exchange (barter) due to your past actions.
  • You say that light "needs" to exist before blah blah. Perhaps not. Perhaps we just live in a simulation, as many believe. In such case, it does not exist as such before reaching our eyes. It does not need to exist. Remember that science does not define the truth. Science is just a set of possible ideas. The fact that scientists are not able to determine if we don't live in a simulator does not mean it is not possible, like the existence of dark matter.

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 :

  1. All that exist are minds or spirits and their ideas.

  2. Light is not a mind or spirit.

  3. Light exists and is therefore an idea.

  4. 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.

  5. Light is such an idea.

  6. The occurrence of any idea must be caused by the will of some being in whose mind the idea occurs.

  7. My ideas of sense are in the mind of, and caused by the will of, some being other than myself.

  8. Therefore my idea of light, or light as an idea, is caused by the will of some being other than myself.

  9. That being is God. (From Berkeleian assumption that my ideas of sense are caused by God.)

  10. Therefore whenever light exists it exists as an idea in the mind of God, who causes my and others' idea of light.

  11. 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.

  12. 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.)

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