 Before delving into some of the technical development, we mention some important objections and alternatives to the AGM framework. As we have mentioned, the belief state of an agent is represented by the (deductively closed) set \(\bB\) of sentences the agent is committed to believe. The structure of the agent’s  reasons is not explicitly represented: you cannot tell of any two \(\alpha,\beta\in \bB\) whether one is a reason for the other. Gärdenfors (1992) distinguishes between  foundations theories, that keep track of which beliefs justify which others, and  coherence theories, which ignore the structure of justification and focus instead on whether beliefs are consistent with one another. Arguing for the coherence approach, he draws a stark distinction between the two: