David Spurrett

The present work is focussed on the completeness of physics, or what is here called the Completeness Thesis: the claim that the domain of the physical is causally closed. Two major questions are tackled: How best is the Completeness Thesis to be formulated? What can be said in defence of the Completeness Thesis? My principal conclusions are that the Completeness Thesis can be coherently formulated, and that the evidence in favour if it significantly outweighs that against it. In opposition to those who argue that formulation is impossible because no account of what is to count as physical can be provided, I argue that as long as the purpose of the argument in which the account is to be used are borne in mind there are no significant difficulties. The account of the physical which I develop holds as physical whatever is needed to fix the likelihood of pre-theoretically given physical effects, and hypothesises in addition that no chemical, biological or psychological factors will be needed in this way. The thus formulated Completeness Thesis is coherent, and has significant empirical content. In opposition to those who defend the doctrine of emergentism by means of philosophical arguments I contend that those arguments are flawed, setting up misleading dichotomies between needlessly attenuated alternatives and assuming the truth of what is to be proved. Against those who defend emergentism by appeal to the evidence, I argue that the history of science since the nineteenth century shows clearly that the empirical credentials of the view that the world is causally closed at the level of a small number of purely physical forces and types of energy is stronger than ever, and the credentials of emergentism correspondingly weaker. In opposition to those who argue that difficulties with reductionism point to the implausibility of the Completeness Thesis I argue that completeness in no way entails the kinds of reductionism which give rise to the difficulties in question. I argue further that the truth of the Completeness Thesis is in fact compatible with a great deal of taxonomic disorder and the impossibility of any general reduction of non-fundamental descriptions to fundamental ones. In opposition to those who argue that the epistemological credentials of fundamental physical laws are poor, and that those laws should in fact be seen as false, I contend that truth preserving accounts of fundamental laws can be developed. Developing such an account, I test it by considering cases of the composition of forces and causes, where what takes place is different to what is predicted by reference to any single law, and argue that viewing laws as tendencies allows their truth to be preserved, and sense to be made of both the experimental discovery of laws, and the fact that composition enables accurate prediction in at least some cases

Bas van Fraassen claims that materialism involves false consciousness. The thesis that matter is all that there is, he says, fails to rule out any kinds of theories. The false consciousness consists in taking materialism to be cognitive rather than an existential stance, or attitude, of deference to the current content of science in matters of ontology, and a favourable attitude to completeness claims about the content of science at a time. The main argument Van Fraassen provides for saying that materialism is not cognitive is an account according to which materialism has responded, so far, to changes in science by abandoning previous hallmarks of the material, and accepting new ones instead of by taking materialism to have been refuted. I argue that van Fraassen’s conclusions run far ahead of what his arguments establish. The fact of revision and revolution in the history of science, and the undoubted provisionality and incompleteness of science as we have it, do indeed tell against simply letting current science determine what the physical is for philosophical purposes. But the alternative to betting on current science need not be unconditional open-endedness. The changes that materialists have accepted so far do not, furthermore, support the false consciousness interpretation. The reason for this is not that materialists will swallow anything, but rather that the changes accepted are consistent with the truth of materialism when appropriately characterized

Cartwright attempts to argue from an analysis of the composition of forces, and more generally the composition of laws, to the conclusion that laws must be regarded as false. A response to Cartwright is developed which contends that properly understood composition poses no threat to the truth of laws, even though agreeing with Cartwright that laws do not satisfy the "facticity" requirement. My analysis draws especially on the work of Creary, Bhaskar, Mill, and points towards a general rejection of Cartwright's view that laws, especially fundamental laws, should be seen as false.

People differ in the extent to which they discount the values of future rewards. Behavioural economists measure these differences in terms of functions that describe rates of reduced valuation in the future – temporal discounting – as these vary with time. They measure differences in preference for risk – differing rates of probability discounting – in terms of similar functions that describe reduced valuation of rewards as the probability of their delivery falls. So-called ‘impulsive’ people, including people disposed to addiction, tend to choose rewards in patterns that are described by unusually steeply sloped discount functions. The empirical literature is ambivalent as to whether this applies to pathological gamblers (PGs) who manifest most other behavioural patterns associated with addiction, with different, equally careful studies suggesting opposite conclusions (Petry & Casarella 1999; Holt, Green & Myerson 2003). This puzzle may arise from the fact that most previous experiments on discounting behaviour were not designed so as to allow effects of high temporal discounting to be distinguished from effects of low probability discounting. (Addiction has sometimes been associated with the latter because it seems to involve, at least in the starting addict, under appreciation of risk.) Our research project investigates both forms of discounting behaviour and their relationship to severity of risk of PG in a community sample of South African gamblers.