Ipse dixit, Latin for "He, himself, said it," is a term used to identify and describe a sort of arbitrary dogmatic statement which the speaker expects the listener to accept as valid. It is also called "the bare assertion fallacy."This must be one of the most frequent logical fallacies. Certainly, I encounter it daily. It is especially common in political or policy discussions where I think it functions more as a signaling device than as a rhetorical device. In other words, if you agree with my ipse dixit, then it is worthwhile continuing the discussion. If not, then it won't be worth talking because I won't/don't want to examine my priors.
Ipse dixit denies that an issue is debatable. In other words, "that's just the way it is."
The fallacy of defending a proposition by baldly asserting it as a fait accompli ("That's just how it is") distorts the argument by opting out of it entirely: "The most basic way to distort an issue is to deny that it exists."
In Bayesian Analysis (a school of statistics), it is important to identify your priors. From SAS.
A prior distribution of a parameter is the probability distribution that represents your uncertainty about the parameter before the current data are examined.In the vernacular, your priors are the quantification of the things you think you know about the problem but aren't certain are true.