Laws of nature support counterfactuals, explain various events and predict others, are confirmed by their instances and help justify induction. Over the past few decades, philosophical interest in just what laws are and how they fulfil this role has grown considerably. This collection brings together a number of important papers from the 1970s onward, covering three central issues.
1. The metaphysics of laws of nature. Are laws entities that ‘govern’? Are they regularities of a certain sort? Both Fred Dretske and Michael Tooley argue that contingent nomic relations between universals (such as F nomically necessitating [or yielding] G) ensure corresponding regularities (such as that all Fs are G), and so govern the way things are and behave. The regularity that all actual Fs are G cannot support the counterfactual ‘if a had been F, it would have been G’, since it is about a possible but non-actual F. But the nomic relational entity F yields G can support counterfactuals, since the closest possible world to ours where a is F also contains that nomic relational entity, and anything that is F instantiates it, and so is G. Regularities, Dretske claims, are not confirmed by their instances; nomic relations between universals are (28). Interestingly, both take laws to be propositions, not the (in their view platonic) relations between universals that those propositions express (22, 68).
Bas van Fraassen criticizes the relations-between-universals account, and David Armstrong's version in particular. Armstrong takes laws to be nomic relations between universals. He also takes them to be immanent entities, rather than platonic. However, there is no reason to think that the proportion of X-particles decaying within two years is .5, even if it is a law that the probability of an X-particle decaying within two years is .5. So how, van Fraassen wonders, can probabilistic laws be immanent? After further objections, he declares that the view that there are no laws seems “no longer much more eccentric than its opposite” (133).
Barry Loewer and Helen Beebee, on the other hand, defend the regularity theory, in the guise of the Ramsey-Lewis view: laws are those theorems or axioms of the true deductive system with the best combination of strength and simplicity (or, in the event of ties, in each equally good system). Loewer defends Humean supervenience—the claim, roughly, that there are local matters of particular fact upon which all other facts (e.g., general, nomic) supervene—by showing how Ramsey-Lewis laws accord with our law-concept. They support counterfactuals, he argues, given Lewis's account of counterfactuals. And a Bayesian account of confirmation allows regularities to be confirmed by their instances (191).
Beebee focuses on intuitions. Take Carroll's example of a world of X-particles and Y-fields, where no X-particle ever goes into a Y-field. Couldn’t it be a law there that all X-particles in Y-fields have spin up, and a law in some physically indistinguishable possible world that they all have spin down? Carroll takes our intuitions to support the answer yes. But Beebee shows that it is not a conceptual truth that laws govern. And as such thought experiments rely on intuitions presupposing a governing conception, using them to argue against the Ramsey-Lewis view amounts to begging the question.
John Bigelow, Brian Ellis, and Caroline Lierse present the only ‘necessitarian’ account in the collection. Laws, they claim, either describe the essential properties of natural kinds or are derivable from them, and so are true in all possible worlds containing the natural kinds involved. The most fundamental laws, such as the conservation laws, describe the essential properties of that natural kind of which the actual world is a member (141). A world's set of essential properties is “the complete catalogue of all its natural laws” (145), but, just as two individuals with different genotypes may nevertheless both be human, so two worlds with different laws may nevertheless be of the same kind (145–146). No other account, they argue, adequately accommodates fundamental laws.
2. ‘Ceteris paribus’ laws. Many statements we take to express laws do not entail or express regularities, nor can we add all the ‘provisos’ to make them do so. Marc Lange, in his paper, argues that Hempel's standard of ‘completeness’ for law-statements—that they must state all the provisos if they are to inform one of the corresponding law—is too high, and we should adopt a normative account of law-statements: ‘so long as there are no disturbing factors’, even if it cannot be unpacked explicitly, is not an empty proviso as long as scientists almost unanimously agree on how to test the law-statement involving it (171). John Earman and John Roberts worry that if the background information possessed by scientists cannot be stated explicitly, the link between science and pseudoscience blurs (219–220). They argue that typical theories of fundamental physics, if true, give us exceptionless fundamental physical laws (214), and that a ‘ceteris paribus law’, if there is such a thing, should be seen as part of “an embryonic theory on its way to being developed to the point where it makes definite claims about the world” (235). Nancy Cartwright presents a third view: the fundamental laws of physics, taken as descriptions of regularities, are false, and adding a ceteris paribus clause to make them true robs them of their explanatory force (e.g., adding ‘if no other forces other than gravitation are at work’ to the law of universal gravitation makes it true, but renders the law unable to explain ordinary cases where other forces are at work [74]). Cartwright's solution is to take these laws as describing the casual powers bodies have (77).
3. The role of laws in induction. John Foster argues that induction is rational only if laws are more than regularities and inference to the best explanation gets us from observed Fs being G to the law that Fs must be G, from which we conclude that other Fs are G (100). Frank Jackson and Robert Pargetter, and Elliot Sober in response, look at confirmation and the projectibility of predicates.
Choosing what to include in a collection can never be an easy matter, but there are a number of conspicuous omissions. Dispositionalism—in which laws hold in virtue of the irreducible dispositionality of properties—is only briefly mentioned. But it is a serious position, acknowledged by Armstrong as perhaps the biggest threat to his own. Swoyer's (Reference Swoyer1982) paper would have been an ideal introduction. Other theories also deserved coverage, such as Fales's (Reference Fales1990) categorical necessitarianism, the view that laws are necessary relations between non-dispositional universals. And where is Armstrong? Why include papers by two relations-between-universals theorists but not the philosopher who developed the fullest account? Reprinting some of Armstrong's published responses to van Fraassen—or, indeed, his arguments against dispositionalism—would have been a useful way into the nuances of his position.
This is a long overdue paperback containing much of interest. But anyone concerned primarily with the metaphysical question of what a law is will come away from it with only an incomplete understanding of the range of options available and the arguments wielded in their support.
