Online research in philosophy

Laws of nature are puzzling because they have a 'modal character'—they seem to be 'necessary-ish'—even though they also seem to be metaphysically contingent. And it is hard to understand how contingent truths could have such a modal character. Scientific essentialism is a doctrine that seems to dissolve this puzzle, by showing that laws of nature are actually metaphysically necessary. I argue that even if the metaphysics of natural kinds and properties offered by scientific essentialism is correct, there are still some metaphysically contingent truths that share the modal character of the laws of nature. I argue that these contingent truths should be considered laws of nature. So even if scientific essentialism is true, at least some laws of nature are metaphysically contingent.

A dispositional property is a tendency, or potency, to manifest some characteristic behaviour in some appropriate context. The mainstream view in the twentieth century was that such properties are to be explained in terms of more fundamental non-dispositional properties, together with the laws of nature. In the last few decades, however, a rival view has become popular, according to which some properties are essentially dispositional in nature, and the laws of nature are to be explained in terms of these fundamental dispositions. The supposed ability of fundamental dispositions to ground natural laws is one of the most attractive features of the dispositional essentialist position. In this paper, however, I cast doubt on the ability of dispositional essences to ground the laws of nature. In particular I argue that the dispositional essentialist position is not able to coherently respond?sympathetically or otherwise?to Cartwright's challenge that there are no true general laws of nature.

I show that Armstrong’s view of laws as second-order contingent relations of ‘necessitation’ among categorical properties faces a dilemma. The necessitation relation confers a relation of extensional inclusion (‘constant conjunction’) on its relata. It does so either necessarily or contingently. If necessarily, it is not a categorical relation (in the relevant sense). If contingently, then an explanation is required of how it confers extensional inclusion. That explanation will need to appeal to a third-order relation between necessitation and extensional inclusion. The same dilemma reappears at this level. Either Armstrong must concede that some properties are not categorical but have essential powers – or he is faced with a regress.

This paper discusses the relationship between dispositions and laws and the prospects for any analysis of talk of laws in terms of talk of dispositions. Recent attempts at such a reduction have often been motivated by the desire to give an account of ceteris paribus laws and in this they have had some success. However, such accounts differ as to whether they view dispositions as properties fundamentally of individuals or of kinds. I argue that if dispositions are properties of individuals, we cannot give a complete account of ceteris paribus laws. Alternatively, if dispositions are properties of kinds, any reductive analysis of laws would require an extension of the notion of the dispositional beyond its usual meaning so that in effect there can be no reduction of laws to dispositions as traditionally understood. An attempt to reduce the nomological to the dispositional is therefore not the way to provide a unified account of traditional and ceteris paribus laws.

Recently several thought experiments have been developed (by John Carroll amongst others) which have been alleged to refute the Ramsey-Lewis view of laws of nature. The paper aims to show that two such thought experiments fail to establish that the Ramsey-Lewis view is false, since they presuppose a conception of laws of nature that is radically at odds with the Humean conception of laws embodied by the Ramsey-Lewis view. In particular, the thought experiments presuppose that laws of nature govern the behavior of objects. The paper argues that the claim that laws govern should not be regarded as a conceptual truth, and shows how the governing conception of laws manifests itself in the thought experiments. Hence the thought experiments do not constitute genuine counter-examples to the Ramsey-Lewis view, since the Humean is free to reject the conception of laws which the thought experiments presuppose.

That laws of nature play a vital role in explanation, prediction, and inductive inference is far clearer than the nature of the laws themselves. My hope here is to shed some light on the nature of natural laws by developing and defending the view that they involve genuine relations between properties. Such a position is suggested by Plato, and more recent versions have been sketched by several writers.~ But I am not happy with any of these accounts, not so much because they lack detail or engender minor difficulties, though they do, but because they share a quite fundamental defect. My goal here is to make this defect clear and, more importantly, to present a rather different version of this general conception of laws that avoids it. I begin by considering several features of natural laws and argue that these are best explained by the view that laws involve properties, that this involvement takes the form of a genuine relation between properties, and, finally, that the relation is a metaphysically necessary one. In the second section I start at the other end, and by reflecting on the nature of properties arrive at a similar account of natural laws. In the final section I develop this account in more detail, with emphasis on the nature of the relation between properties it invokes. Along the way several natural objections to the account are answered.

In this paper I discuss and evaluate different arguments for the view that the laws of nature are metaphysically necessary. I conclude that essentialist arguments from the nature of natural kinds fail to establish that essences are ontologically more basic than laws, and fail to offer an a priori argument for the necessity of all causal laws. Similar considerations carry across to the argument from the dispositionalist view of properties, which may end up placing unreasonable constraints on property identity across possible worlds. None of my arguments preclude the possibility that the laws may turn out to be metaphysically necessary after all, but I argue that this can only be established by a posteriori scientific investigation. I therefore argue for what may seem to be a surprising conclusion: that a fundamental metaphysical question – the modal status of laws of nature – depends on empirical facts rather than purely on a priori reasoning.

This book advocates dispositional essentialism, the view that natural properties have dispositional essences.1 So, for example, the essence of the property of being negatively charged is to be disposed to attract positively charged objects. From this fact it follows that it is a law that all negatively charged objects will attract positively 10 charged objects; and indeed that this law is metaphysically necessary. Since the identity of the property of being negatively charged is determined by its being related in a certain way to the property of being positively charged, in any world in which these properties exist they must be related so that all negatively charged objects attract positively charged objects. 15 Bird opposes his dispositional essentialism to the view that properties are categorical in nature, with their identities grounded in quiddities that are not exhausted by their relations to other properties. The main exponents of this view are D.M. Armstrong and David Lewis. They take the laws of nature to be contingent though they entertain very different views about their nature: Armstrong is a necessitarian 20 about laws, taking them to be relations of nomic necessitation between universals, while Lewis is a Humean about laws who takes them to be a special kind of regularity. The book is a sustained defence of the dispositional essentialist conception of properties and laws against the competing conceptions espoused by Armstrong and Lewis. One rough way to characterize the difference between these conceptions is to say that 25 the categoricalist sees properties as passive and inert with the laws of nature being fixed independently of the nature of properties whereas, in contrast, the dispositional essentialist sees properties as active potencies from which the laws of nature automatically spring. A slightly more tendentious way to express the difference is to say, as Bird does, that the categoricalist views embrace the Humean doctrine that there are no 30 necessary connexions in nature, while the dispositional essentialist view, on the other hand, repudiates this doctrine..

Those who favour an ontology based on dispositions are thereby able to provide a dispositional essentialist account of the laws of nature. In part 1 of this paper I sketch the dispositional essentialist conception of properties and the concomitant account of laws. In part 2, I characterise various claims about the modal character of properties that fall under the heading ‘quidditism’ and which are consequences of the categoricalist view of properties, which is the alternative to the dispositional essentialist view. I argue that quidditism should be rejected. In part 3, I address a criticism of a strong dispositional essentialist view, viz. that ‘structural’ (i.e. geometrical, numerical, spatial and temporal) properties must be regarded as categorical.

Debate between Humean contingentists and anti-Humean necessitarians in the philosophy of science is ongoing. One of the most important contemporary anti-Humeans is Alexander Bird. Bird calls the particular version of Humeanism he is opposed to 'categoricalism'. In his paper (2005) and in Chapter 4 of his book (2007) Bird argues against categoricalism about properties and laws. His arguments against categoricalism about properties are intended to support the necessitarian position he calls dispositional monism. His arguments against categoricalism about laws are intended to refute the contingent regularity view of laws (even in its sophisticated Lewisean version) and the nomic necessitation view of Armstrong (which involves a contingent necessitation relation). The general position Bird defends is that properties are necessarily related to the dispositions they bestow on their bearers and laws are necessary truths. I consider two of Bird's arguments against categoricalism about properties, and one of his arguments against the regularity view of laws. Maybe other arguments against categoricalism are persuasive. These, I submit, are not.