A fined tuned argument.....Heywood style.

[Angrboda]

If A and B both have a 50% probability of being true then the probability of the existence of a creating intellect goes above 50%.

The reason this would be the case is because 50% of the time A is true and by necessity of it being true a creating intellect exists.

However if B is true the multiverse itself could still have been created by an intellect. Unless you can show the existence of a multiverse positively excludes the existence of a creating intellect, you have to acknowledge there is some probability, call it X, that a creating intellect exists. X might be exceedingly small...but it is not 0.

If A and B are equally likely, the probability of the existence of a creating intellect is 50% + X.

The principle of indifference states that if the n possibilities are indistinguishable except for their names, then each possibility should be assigned a probability equal to 1/n.

Since you're now claiming we have additional information (that B could be caused by an intellect), then the Principle of Indifference no longer applies (indeed, never applied, as we have many ways of distinguishing these alternatives). So you've just eliminated the Principle of Indifference as a valid rule for applying probabilities, so you cannot any longer say that the probabilities should be assigned 50 / 50 on that basis. You never could. You've misapplied the Principle of Indifference.