Probability

Suppose that I know all the laws of physics and the position of all the atoms in the universe. I flip a coin. Obviously I will know with 100% certainty what the outcome will be. Suppose I am a mere mortal, I will only be able to say that there is a 50% chance of heads and a 50% chance of tails. So probability is a measure of our ignorance? That cannot be right! Probability is something intrinsic to reality. But how can an uncertainty be intrinsic without reference to a knower?

Comments

Sometimes probability is a measure of our ignorance. If you give me a quarter with the instruction to hide it in one of my fisted hands while your eyes are closed (and I do as you say), then you'll not know which hand holds the coin. (I will know, I can feel it.) So you can only assign probabilities because you lack knowledge.

In other cases, probability is objective. If current physics is right, then some processes in nature are in principle unpredictable or such that their outcome is uncertain. Yes, this suggests some reference to a knower: it means that it's impossible for there to be someone who can predict or be certain about the outcome. But why should this be problematic? The fact that a black hole emits no light can be expressed by saying that black holes are invisible - and yet the fact is "intrinsic to reality," involves no essential reference to beings with eyes.

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