Doxastic Attitudes as Belief-Revision Policies

While propositional doxastic attitudes, like knowledge and belief, capture an agent’s opinion about certain propositions, her attitudes towards sources of information express her opinion about the reliability (or trustworthiness) of those sources. If an agent trusts a witness, then she will, within certain limits, tend to accept his testimony as veridical. But if she considers the witness to be a notorious liar, she may come to believe the opposite of what he tells her. In this paper, we put such attitudes towards sources (or dynamic (doxastic) attitudes) center stage, and formalize them as belief-revision strategies: policies governing how an agent changess her beliefs whenever new information from a certain (type of) source is received. We present a semantic, qualitative modelling of this notion and investigate its properties.