This paper summarizes basic concepts and principles that I have found to be useful in dealing with causal reasoning. The paper is written as a companion to a lecture under the same title, to be presented at IJCAI-99, and is intended to supplement the lecture with technical details and pointers to more elaborate discussions in the literature. The ruling conception will be to treat causation as a computational schema devised to identify the invariant relationships in the environment, so as to facilitate reliable prediction of the effect of actions. This conception, as well as several of its satellite principles and tools, has been guiding paradigm for several research communities in AI, most notably those connected with causal discovery, troubleshooting, planning under uncertainty and modeling the behavior of physical systems. My hopes are to encourage a broader and more effective usage of causal modeling by explicating these common principles in simple and familiar mathematical form. Af...

The ABL rule is derived and shown to be a tool of standard quantum mechanics. Objections by Kastner [quant-ph/0003098v3] and others to the counterfactual use of the ABL rule are shown to be groundless. In particular, this use is not restricted in the way Kastner has claimed. A variant of the three-box experiment due to Vaidman is discussed. It is argued that Born probabilities (and hence state vectors or density operators) are not the right basis for drawing ontological inferences. What quantum mechanics is trying to tell us about the world must be inferred from the objective ABL probabilities that are assigned to counterfactuals. The correct inferences, however, will remain incomprensible until a prevalent but inconsistent way of thinking about the temporal aspect of the world is rejected. 1 OBJECTIVE PROBABILITIES AND THE ABL RULE Following Mermin [1], I characterized some of the probabilities that quantum mechanics allows us to calculate as being objective in the sense that they have nothing to do with ignorance—there is nothing for us to be ignorant of [2]. In order to be objective, they

Inscrutability arguments threaten to reduce interpretationist metasemantic theories to absurdity. Can we find some way to block the arguments? A highly influential proposal in this regard is David Lewis ’ ‘eligibility ’ response: some theories are better than others, not because they fit the data better, but because they are framed in terms of more natural properties. The purposes of this paper are (1) to outline the nature of the eligibility proposal, making the case that it is not ad hoc, but instead flows naturally from three independently motivated elements; and (2) to show that severe limitations afflict the proposal. In conclusion, I pick out an element of the eligibility response that is responsible for the limitations. 1 The philosophy of intentionality asks questions such as: in virtue of what does a sentence, picture, or mental state represent that the world is a certain way? The sub-question I focus upon here concerns the semantic properties of language: in

Philosophers have appealed to information (as understood by [Shannon, 1948] and introduced to philosophers largely by [Dretske, 1981]) in a wide variety of contexts; information has been proffered in the service of understanding knowledge, justification, and mental content, inter alia. While information has been put to diverse philosophical uses, there has been much less diversity in the understanding of information itself. In this paper we’ll offer a novel theory of information that differs from traditional accounts in two main (and orthogonal) respects: (i) it explains information in terms of counterfactuals rather than conditional probabilities, and (ii) it does not make essential reference to doxastic states of subjects, and consequently allows for the sort of objective, reductive explanations of notions in epistemology and philosophy of mind that many have wanted from an account of information. We’ll first present our counterfactual account of information (§1), and show how it sidesteps a problem that has been raised for its traditional, probabilistic competitors (§2). Next we’ll compare the counterfactual account against that proposed by Dretske (§3), highlighting the differences between the two. After that, we’ll turn to questions about objectivity: we’ll bring out a conflict between the essentially doxastic character of traditional theories of information and the reductive purposes philosophers have had in mind in appealing to information (§4), and we’ll show how the account of §1 can be formulated in non-doxastic terms. Finally, we’ll consider objections against the proposed account (§5). Ultimately, we’ll suggest, the objective counterfactual account of information should be taken as a serious contender to more traditional rivals. 1 Counterfactuals and Information 1.1 A Crude Counterfactual Account It is a plausible and widely accepted view that informational relations require not only simple (actual) covariation, but also counterfactual variation. For ex-∗ This work is fully collaborative; the authors are listed in alphabetical order.

John Hawthorne in a recent paper takes issue with Lewisian accounts of counterfactuals, when relevant laws of nature are chancy. I respond to his arguments on behalf of the Lewisian, and conclude that while some can be rebutted, the case against the original Lewisian account is strong. I develop a neo-Lewisian account of what makes for closeness of worlds. I argue that my revised version avoids Hawthorne’s challenges. I argue that this is closer to the spirit of Lewis’s first (non-chancy) proposal than is Lewis’s own suggested modification. 1 Counterfactuals and Chance The antecedents of some counterfactual statements render their consequent hugely probable, but not certainly true. That is, it is not impossible that a combination of unlikely coincidences could lead to a situation in which the antecedent is true and the consequent false. For example: (A) If I were to toss this fair coin 10,000,000 times, it would not come up heads every time.

Abstract not found

This article presents a novel interpretation of quantum mechanics. It extends the meaning of “measurement ” to include all property-indicating facts. Intrinsically space is undifferentiated: there are no points on which a world of locally instantiated physical properties could be built. Instead reality is built on facts, in the sense that the properties of things are extrinsic, or supervenient on the facts. The actual extent to which the world is spatially and temporally differentiated (that is, the extent to which spatio-temporal relations and distinctions are warranted by the facts) is necessarily limited. Notwithstanding that the state vector does nothing but assign probabilities, quantum mechanics affords a complete understanding of the actual world. If there is anything that is incomplete, it is the actual world, but its incompleteness exists only in relation to a conceptual framework that is more detailed than the actual world. Two deep-seated misconceptions are responsible for the interpretational difficulties associated with quantum mechanics: the notion that the spatial and temporal aspects of the world are adequately represented by sets with the cardinality of the real numbers, and the notion of an instantaneous state that evolves in time. The latter is an unwarranted (in fact, incoherent) projection of our apparent “motion in time ” into the world of physics. Equally unwarranted, at bottom, is the use of causal concepts. Therer nevertheless exists a “classical ” domain in which language suggestive of nomological necessity may be used. Quantum mechanics not only is strictly consistent with the existence of this domain but also presupposes it in several ways. I.