A unified model of qualitative belief change: a dynamical systems perspective

Belief revision and belief update have been proposed as two types of belief change serving different purposes, revision intended to capture changes in belief state reflecting new information about a static world, and update intended to capture changes of belief in response to a changing world. We argue that routine belief change involves elements of both and present a model of generalized update that allows updates in response to external changes to inform an agent about its prior beliefs. This model of update combines aspects of revision and update, providing a more realistic characterization of belief change. We show that, under certain assumptions, the original update postulates are satisfied. We also demonstrate that plain revision and plain update are special cases of our model. We also draw parallels to models of stochastic dynamical systems, and use this to develop a model that deals with iterated update and noisy observations in (qualitative settings) that is analogous to Bayesian updating in a quantitative setting. Some parts of this report appeared in preliminary form in “Generalized Update: Belief Change in Dynamic Settings,” Proc. of Fourteenth International Joint Conf. on Artificial Intelligence (IJCAI-95), Montreal, pp.1550–1556 (1995)

Professor William Craig’s Criticisms of Critiques of Kalam Cosmological Arguments By Paul Davies, Stephen Hawking, and Adolf Grunbaum

Kalam cosmological arguments have recently been the subject of criticisms, at least inter alia, by physicists---Paul Davies, Stephen Hawking---and philosophers of science---Adolf Grunbaum. In a series of recent articles, William Craig has attempted to show that these criticisms are “superficial, iII-conceived, and based on misunderstanding.” I argue that, while some of the discussion of Davies and Hawking is not philosophically sophisticated, the points raised by Davies, Hawking and Grunbaum do suffice to undermine the dialectical efficacy of kalam cosmological arguments

Is Everything Revisable?

Over the decades, the claim that everything is revisable (defended by Quine and others) has played an important role in Epistemology and Philosophy of Science. Some time ago, Katz (1988) argued that this claim is paradoxical. This paper does not discuss this objection but rather argues that the claim of universal revisability allows for two different readings but in each case leads to a contradiction and is false

Reverse Bayesianism and Act Independence

Karni and Vierø (2013) propose a model of belief revision under growing awareness—reverse Bayesianism—which posits that as a person becomes aware of new acts, consequences, or act-consequence links, she revises her beliefs over an expanded state space in a way that preserves the relative likelihoods of events in the original state space. A key feature of the model is that reverse Bayesianism does not fully determine the revised probability distribution. We provide an assumption—act independence—that imposes additional restrictions on reverse Bayesian belief revision. We show that with act independence knowledge of the probabilities of the new act events in the expanded state space is sufficient to fully determine the revised probability distribution in each case of growing awareness. We also explore what additional knowledge is required for reverse Bayesianism to pin down the revised probabilities without act independence

The Manifestation Challenge: The Debate between McDowell and Wright

In this paper, we will discuss what is called the “Manifestation Challenge” to semantic realism, which was originally developed by Michael Dummett and has been further refined by Crispin Wright. According to this challenge, semantic realism has to meet the requirement that knowledge of meaning must be publically manifested in linguistic behaviour. In this regard, we will introduce and evaluate John McDowell’s response to this anti-realistic challenge, which was put forward to show that the challenge cannot undermine realism. According to McDowell, knowledge of undecidable sentences’ truth-conditions can be properly manifested in our ordinary practice of asserting such sentences under certain circumstances, and any further requirement will be redundant. Wright’s further objection to McDowell’s response will be also discussed and it will be argued that this objection fails to raise any serious problem for McDowell’s response and that it is an implausible objection in general

Reasoning about Uncertain Information and Conflict Resolution through Trust Revision

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