Logical dynamics of some speech acts that affect obligations and preferences

. In this paper, illocutionary acts of commanding will be differentiated from perlocutionary acts that affect preferences of addressees in a new dynamic logic which combines the preference upgrades introduced by van Benthem and Liu in [vBLar] with deontic updates introduced by Yamada in [Yam07b]. The resulting logic will incorporate Austin’s distinction between illocutionary acts as acts having mere conventional effects and perlocutionary acts as acts having real effects upon attitudes and actions of agents, and help us understand why saying so can make things so in explicit performative utterances.