*Speaker: Franz Berto (U. St Andrews & ILLC, U. Amsterdam) *Title: Half Empty vs Half Full: Belief Revision and the Framing Effect *Abstract: The dominant logical theory of belief revision, AGM (Alchourron, Gärdenfors and Makinson), imposes an amount of idealisation on cognitive agents revising their beliefs in the light of new information: their belief states are perfectly consistent, closed under the full force of classical logic, and they know all logical truths. Humans are not like that: they can hold inconsistent beliefs; their belief states are not classically closed; and they can be subject to framing effects, revising their beliefs in different ways when presented with logically equivalent options (‘If you apply for the job, you have 40% chances of making it’ vs ‘… you have 60% chances of failing’). Behavioural economics has shown the momentous consequences of framing in social choice and decision theory, where presenting the same situation positively (‘glass half full’) or negatively (‘glass half empty’) can lead to dramatically different beliefs and choices. In this talk, I present a semantics for a belief revision operator which is hyperintensional, that is, capable of modelling distinctions more fine-grained than classical logical equivalence, and in particular, framing effects and inconsistent beliefs. Unlike most approaches to belief revision for non-ideal agents, my semantics does not resort to non-classical logics. The framework combines, instead, a standard semantics for propositional modal logic with a simple mereology of contents. *Bio: Franz Berto is the chair of logic and metaphysics at the university of St Andrews and a research chair at the Institute for Logic, Language and Computation at the university of Amsterdam. He works more or less on anything nonclassical: non-standard ontology, non-classical modal and epistemic logic, and the philosophy of parallel computation. He has written a number papers on these topics, and books with Oxford University Press, Blackwell, King’s College, Synthese Library, Bloomsbury. He has held research positions at the Institute for Advanced Study at the University of Notre Dame, at the Sorbonne and CNRS in Paris, at the University of Aberdeen, and at the Netherlands Institute for Advanced Study. *When: Thursday 7th of June 2018, 12:00-13:00 *Location: Manno, Galleria 1, 2nd floor, room G1-204 *Registration: Pizza (or alternative food) and drinks will be offered at the end of the talk. If you plan to attend, please register in a timely fashion at the following link so that we will have no shortage of food: https://doodle.com/poll/24yvbd6rgs68zarx