- I'll see if I can find an official statement, but sure think we're expected to "speculate" in Bayesian statistics.
one is not encouraged to "speculate" in bayesian statistics so much as to make the background information you are using explicit.
in his book, Good Thinking: The Foundations of Probability and Its Applications, IJ Good has a paper in which he discusses the 46656 varieties of bayesian. there are more today. but none of them suggest one "speculate" in terms of "just make stuff up without a foundation".
the aim (as i read it) is to reach robust probability statements that would generally be agreed upon by all, and when that is not possible to agree that no robust statements can be made and to still find agreement on why this is the case.