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?

  • 3
    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 '18 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. Aug 28 '18 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? Aug 28 '18 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. Aug 29 '18 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. Aug 29 '18 at 9:51

I am not aware that Berkeley's offers an account of light at any length outside his 'A New Theory of Vision' (1709). He there refers to light as consisting in 'rays':

... the particles which compose our atmosphere intercept the rays of light proceeding from any object to the eye : New Theory of Vision, §68. This language is entirely typical of the way Berkeley talks of light throughout the text.

Always he uses the language of 'rays' of light proceeding - travelling, moving - towards the eye. It is not clear how, if there are only minds and their ideas, ideas can 'proceed'. Ideas can't literally move, surely : proceed from one spatial location to another.

The only way out seems to be to say that God creates certain ideas which we experience as light. As created by God and preserved in existence by God, and perceived by us, these ideas are never unperceived.

While I think this is what Berkeley should say and does believe, his language of rays of light 'proceeding' from object to eye is physicalist and cannot be taken literally from his own viewpoint. Here does, indeed, think with the wise and speak with the vulgar (Principles of Human Knowledge, §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.

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