If anyone wants to defend the best system theory of laws and chances both (as opposed to the best system theory of laws, given chances), I suppose the right move would be to cripple the Principal Principle by declaring that information about the chances at a time is not, in general, admissible at that time; and hence that hypothetical information about chances, which can join with admissible historical information to imply chances at a time, is likewise inadmissible.