Rational status quo

Decision makers often stick to a status quo without explicitly reconsidering it. Yet, their observed choices might be compatible with a fully rational model. We ask when such a rationalization is possible. We assume as observable only the choice of sticking to the status quo vs. changing it, as a function of a database of cases. We state conditions on the set of databases that would make the decision maker change the status quo, which are equivalent to the following representation: the decision maker entertains a set of theories, of which one is that her current choice is the best; she is inert as long as that theory beats any alternative theory according to a maximum likelihood criterion.