[chriselrod]

Your "3" is a Bayesian view. Specifically, from the Jaynesian school, which views probability as ignorance. When we can't calculate which of those world's we're in, we express our remaining uncertainty with probability. The connection to subjective "beliefs" is recognizing that these probabilities are all in our own heads. Believing otherwise is the "mind projection fallacy"; in reality -- as you noted -- these things are certain from the god's eye view, and we fall somewhere in between that and total ignorance/entropy. (I'm not a physicist, but I know some use the Many Worlds interpretation to apply this determinism even to quantum physics.)

E.T. Jaynes fleshes out his worldview in "Probability Theory: The Logic of Science", which was published posthumously in 2003.

[kgwgk]

> Your "3" is a Bayesian view.

Except for the infinite number of universes nonsense :-)

[kgwgk]

Dear downvoters: Even if we assume an infinite number of (real or imaginary) universes, what does “in exactly half of the worlds" mean? This definition doesn’t seem at all less problematic that the usual ones.

[perl4ever]

I think "infinite" is just sloppy language. If every possible universe exists in some sense, that is a large number, but not infinite - because nothing about a universe has infinite precision. Thus, "half" would still mean something.