I think that could have read "At time T=1, the mind has 10 bits of mutual information... at time T=2, the mind has 100 bits of mutual information," and meant the same thing. Meaning, he's saying that, if during any time period the mind has acquired mutual information with S, then mind must have encountered evidence. This doesn't preclude us from starting out with some bits of information. The statement is about the change in the amount of information; starting from 0 is just convenient for the explanation.
Silas,
I think that could have read "At time T=1, the mind has 10 bits of mutual information... at time T=2, the mind has 100 bits of mutual information," and meant the same thing. Meaning, he's saying that, if during any time period the mind has acquired mutual information with S, then mind must have encountered evidence. This doesn't preclude us from starting out with some bits of information. The statement is about the change in the amount of information; starting from 0 is just convenient for the explanation.