Online research in philosophy

Of knowledge and probability: a quick tour of part 3, book 1. Of knowledge ; Of probability; and of the idea of cause and effect ; Why a cause is always necessary? ; Of the component parts of our reasonings concerning causes and effects ; Of the impressions of the senses and memory ; Of the inference from the impression to the idea ; Of the nature of the idea, or belief ; Of the causes of belief ; Of the effects of other relations, and other habits ; Of the influence of belief ; Of the probability of chances ; Of the probability of causes ; Of unphilosophical probability ; Of the idea of necessary connexion ; Rules by which to judge of causes and effects ; Of the reason of animals -- Hume on unphilosophical probabilities -- Hume's skepticism with regard to reason -- Of skepticism with regard to the senses -- Of the ancient and modern philosophy -- The soul and the self -- The conclusion of book 1 -- Two openings and two closings.

John Leslie presents a thought experiment to show that chances are sometimes observer-relative in a paradoxical way. The pivotal assumption in his argument – a version of the weak anthropic principle – is the same as the one used to get the disturbing Doomsday argument off the ground. I show that Leslie's thought experiment trades on the sense/reference ambiguity and is fallacious. I then describe a related case where chances are observer-relative in an interesting way. But not in a paradoxical way. The result can be generalized: At least for a very wide range of cases, the weak anthropic principle does not giverise to paradoxical observer-relative chances. This finding could be taken to give new indirect support to the doomsday argument.

I argue that there are non-trivial objective chances (that is, objective chances other than 0 and 1) even in deterministic worlds. The argument is straightforward. I observe that there are probabilistic special scientific laws even in deterministic worlds. These laws project non-trivial probabilities for the events that they concern. And these probabilities play the chance role and so should be regarded as chances as opposed, for example, to epistemic probabilities or credences. The supposition of non-trivial deterministic chances might seem to land us in contradiction. The fundamental laws of deterministic worlds project trivial probabilities for the very same events that are assigned non-trivial probabilities by the special scientific laws. I argue that any appearance of tension is dissolved by recognition of the level-relativity of chances. There is therefore no obstacle to accepting non-trivial chance-role-playing deterministic probabilities as genuine chances.

This paper considers the ethical issues raised by xenotransplantation underfour headings: interfering with nature; effects on the recipient; effects on other humans; and effects on donor animals. The first two issues raise no insuperable problems: charges of unnaturalness are misguided, and the risks that xenotransplantation carries for the recipient are a matter for properly informed consent. The other two issues raise more serious problems, however, and it is argued that if we take seriously the risk of transferring new infectious agents from animal to human populations and the interests of donor animals, then a moratorium on xenotransplantation is called for. The paperfinds that the recent Nuffield Council and Department of Health reports on xenotransplantation are insufficiently cautious in the conclusions that they draw from these considerations.

considers what I call free-floating chances—objective chances that obtain at a given time despite the fact that their values are not determined by the laws of nature together with the full history of non-chancy facts up to that time. I offer an intuitive example of this phenomenon, and use it to argue that free-floating chances are indeed possible. Their possibility violates three quite widely held principles about chances: the lawful magnitude principle, the principle that chances evolve by conditionalization and a version of David Lewis' principal principle. I argue that we should reject common formulations of each of these principles, though I offer revised understandings of each which retain much of the intuitive attractiveness of the originals and are consistent with the possibility of free-floating chances. I conclude by arguing that, while considerations of free-floating chances are important, they will not sustain the extravagant conclusions Lange attempts to draw from them. Introduction First- and Higher-Order Chances Free-Floating Chances Support for the Intuitive Assessment Three Principles Violated What to do? COND as a Default Hypothesis A More Principled Principal Principle Conclusion.

A common line of argument for the impossibility of closed causal loops is that they would involve causal paradoxes. The usual reply is that such loops impose heavy consistency constraints on the nature of causal connections in them; constraints that are overlooked by the impossibility arguments. Hugh Mellor has maintained that arguments for the possibility of causal loops also overlook some constraints, which are related to the chances (single-case, objective probabilities) that causes give to their effects. And he argues that a consideration of these constraints demonstrates that causal loops are impossible. I consider Mellor's argument and more generally the nature of chance in causal loops. I argue that Mellor's line of reasoning is unwarranted since it is based on untenable premisses about the relation between chances and long-run frequencies in causal loops. Yet, this line of reasoning may still be of interest to those who maintain that causes determine the chances of their effects; for it raises some unresolved questions about the nature of chance in causal loops.

I offer an argument regarding chances that appears to yield a dilemma: either the chances at time t must be determined by the natural laws and the history through t of instantiations of categorical properties, or the function ch(•) assigning chances need not satisfy the axioms of probability. The dilemma's first horn might seem like a remnant of determinism. On the other hand, this horn might be inspired by our best scientific theories. In addition, it is entailed by the familiar view that facts about chances at t are ontologically reducible to facts about the laws and the categorical history through t. However, that laws are ontologically prior to chances stands in some tension with the view that chances are governed by laws just as categorical-property instantiations are. The dilemma's second horn entails that if chances are in fact probabilities, then this is a matter of natural law rather than logical or conceptual necessity. I conclude with a suggestion for going between the horns of the dilemma. This suggestion involves a generalization of the notion that chances evolve by conditionalization. Introduction "Chances evolve by conditionalization" How might the lawful magnitude principle be defended? A historical interlude What if chances failed to be determined by the laws and categorical facts?

The general claims of this paper are as follows. As a result of chaotic dynamics we can usually not know what the deterministic causes of events are. There will, however, be invariant forwards transition chances from earlier types of events, which we typically call the causes, to later types of events, which we typically call the effects. There will be no invariant backwards transition chances between these types of events. This asymmetry has the same origin and explanation as the arrow of time of thermodynamics.