What a Law of Nature is
W. Russ Payne Ph.D.
In this paper I develop and defend a view of causal laws as analyses of dispositions. I take a disposition to be the property of having some causal base property Ė a property such that a manifestation of the disposition would be produced were its precipitating conditions to obtain. On this view, dispositions are analyzed as complex relational properties. But dispositions are not themselves causal powers. Causal powers are had by the dispositionís causal base property. As property analyses, causal laws are necessary truths. But a further condition on a property analysis being a law is that it analyzes a property that is in fact instantiated. Things might have had fundamentally different dispositions. In this case, different property analyses would have been laws. The alleged intuition that laws are contingent turns out to be the correct intuition that fundamentally different properties might have been instantiated. Concerns about the explanatory value of disposition ascriptions and the epistemological status of laws as property analyses are also addressed.
The title of David Armstrongís book on the topic asks "What is a Law of Nature?" The answer I will develop and motivate in this paper is that causal laws are analyses of dispositions. We typically describe dispositions in terms of subjunctive conditionals. For sugar to be soluble in water, for instance, is just for it to be such that if it were submerged in water (under appropriate conditions), it would dissolve. In general, we can say that for a thing to have a disposition is for it to be such that were certain precipitating conditions to obtain, then a certain manifestation of the disposition would occur. In the case of solubility, being submerged in water (under appropriate conditions) is the precipitating condition for the manifestation of going into solution. A careful account of the conditions under which sugar would go into solution in water, that is, an account of the specific nature of its solubility, would be an analysis of sugarís solubility in water and a statement of law. That statement of law tells us something about the nature of sugar in terms of the dispositions it grounds. This view of laws will be developed in terms of an independently motivated view of analysis. Analyses, on this view, are accounts of the nature of complex properties or relations in terms of their simpler component properties and relations and how they are structured in the analysandum. The objects of analysis on this view are mind independent entities and thus are suitable objects for scientific inquiry.
The view that laws are necessarily true accounts of the essentially dispositional nature of properties has advocates in Brian Ellis and Caroline Lierse, Alan Chalmers, Sydney Shoemaker and John Bigelow among others. What distinguishes the account I will offer is the explicit metaphysics of dispositions as relational properties whose causal bases are "dispositional" in the distinct sense of having their causal powers essentially. Distinguishing relational dispositions from properties that are dispositional in the sense of having their causal powers essentially affords a clear reply to Armstrongís concern that dispositional properties are somehow not sufficiently actual to ground laws.
We have apparently conflicting modal intuitions about laws. On the one hand we think events in the world could have unfolded in accordance with different laws. On the other, it seems that laws must have some kind of necessity in order to explain and support counterfactuals. A primary virtue of the account I will propose here is that it provides a diagnosis and resolution of this apparent conflict. The view that causal laws are analyses of dispositions makes these laws of nature necessary truths. But it remains a contingent matter that things instantiate the dispositions they do. This allows for a natural account of the alleged intuition that the laws might have been different. Specifically, the intuition that the laws of nature are contingent truths turns out to just be the intuition that things might have had fundamentally different properties.
Before I develop the proposed account of causal laws as analyses of dispositions, I will say a few words about the inadequacies of alternative realist account of laws. After developing the proposed account in some detail, I will consider and answer a few potential objections. Specifically, I will address concerns about the epistemic status of laws as necessarily true property analyses, concerns about the explanatory power of dispositions and the intuition that the laws could have been different.
Finally, by way of introduction, I should say a few words about the role of Platonism in this paper. I will employ an abundant Platonist conception of properties as an analytic tool in developing the proposed account. On this conception, there is a property expressed by any unambiguous and non-paradoxical predicate of any possible language (and perhaps there are even more properties). But my purpose in this paper is not to defend any particular position regarding the problem of universals. The issues I am concerned with here are issues for Platonists and in re realists. For the purpose of maximizing clarity in addressing these issues, I want to adopt the most powerful explanatory framework available and that framework is abundant Platonism about properties and relations. I am a realist about properties and relations, but I am officially agnostic on the matter of abundant Platonism vs. sparse in re realism. The extant literature on dispositional essentialism has, in my view, failed to clearly address a range of objections that can be adequately addressed because the ontological commitment of many authors to sparse in re realism has unnecessarily constrained their methodology. In this paper I aim to correct this methodological shortcoming.
I will not address regularity theories of laws. I think they fail for reasons that are well documented in the work of William Kneale, David Armstrong and John Carrol among others. The failure of regularity accounts of laws has lead to the ascendancy of the realist account of laws offered independently by Armstrong, Tooley, and Dretske. These authors defend the view that laws are nomic relations that hold between universals. So, for instance, for it to be a law that water expands when it freezes is just for the universals being water, freezing and expanding to stand in the appropriate nomic relation. In adherence to the alleged intuition that the laws of nature are contingent, these authors each take nomic relations to hold between universals contingently. On this view, properties have causal powers but have their causal powers contingently in virtue of the nomic relations they stand in. It is worth noting that Chris Swoyer was alone among the early proponents of the realist view of laws to take nomic relations between universals to hold necessarily.
I will give three objections the realistís view where laws are taken to be contingent nomic relations holding between universals. I believe that these objections jointly, if not individually, provide compelling grounds for rejecting contingent nomic relations. The first regards the modal status of laws. The second problem concerns a proliferation of ways the world could be that results from allowing that properties might have had different causal powers. These first two problems have been widely discussed in the literature on dispositional essentialism. To these I will add a third objecton, namely that contingent nomic relations beg the question against the possibility of Platonism about properties and relations.
In order to account for the explanatory role of laws and their role in supporting counterfactuals, the realistís nomic relations, while contingent, are taken to have a modal status lacked by the contingent relation of co-instantiation already recognized on regularity accounts. This requires attributing some kind of necessity to laws. Armstrong does so in the following passage:
In a counterfactual supported by laws, the laws call the tune. Why is this? I take it that it is because the laws involve something which the regularity theory denies them to have, and which particular states of affairs do not have: a certain necessity (which need not be logical). They say what must happen, and so they have authority in counterfactual reasoning.
However, if we are to recognize some intermediate grade of necessity between metaphysical necessity and mere accident, then we ought to be able to give some non-question begging account of it. This general concern is raised by Lewis and van Frassen and developed in more detail in Bird. This is indeed the point of David Lewis well known joke that calling this relation natural necessitation no more makes it so than "one can have mighty biceps just by being called Armstong." An adequate account of this supposed intermediate grade of necessity must go some ways towards a demarkation of just what worlds are invariant with respect to the laws. This is required for our having grounds to expect that the laws remain true at the relevant counterfactual antecedent worlds. But this requirement has not been met by Armstrong or any extant account of contingent nomic relations. Nor do the prospects look good.
A further problem for the view that nomic relations hold among universals contingently is that it leads to a proliferation of possible ways the world could be that is unparsimonious and counter-intuitive. The only differences we can posit as the essential distinguishing features of fundamental properties like charge or mass are differences in their causal powers. Armstrong is prepared to accept this result and take the identity of fundamental properties as primitive. But, accepting "bare universals," as I will call such properties, leads to some peculiar possibilities. Specifically, it opens up the possibility of what Brian Ellis calls a "global transubstantiation," an empirically indistinguishable world containing different kinds of things and processes. A global transubstantiation of the actual world would be a world that differed only with regard to what properties have what causal powers and instances. For instance, suppose that charge and mass are the underlying causal base properties respectively for the dispositions of electrons to push away from each other and for massive bodies to attract. On Armstrongís view, there is a possible way the world could be, a global transubstantiation, that is exactly like the actual world except that charge and mass have swapped their all of their causal powers and instances. This global transubstantiation would be empirically indistinguishable from the actual world. Yet it will have different laws on Armstrongís view in virtue of its universals being differently nomically related. There will be another such world that is exactly like the actual world except with regard to which properties have which causal powers and instances for every possible assignment of basic properties as causal bases for basic dispositions.
There seems to be something unparsimonious about global transubstantiations. For modal realists there really is something unparsimonious about global transubstantiations. For others, though, while perhaps unlovely, such a proliferation of possibilities is not as grave as a proliferation of entities. A more serious problem is that itís hard to get over the feeling that the laws are really the same at global transubstantiations. Global transubstantiations of the actual world will be empirically indistinguishable from the actual world. The differences between such worlds have nothing to do with how we understand, confirm, investigate, or express laws. Worlds that differ only with regard to which properties have which powers will be exactly like the actual world with respect to what (non-nomic) counterfactuals are true, what dispositions things have and which inductive inferences are correct. For all of these reasons we should like to hold that the laws in each such world are the same. We want to say, for instance, that Coulomb's law really holds at global transubstantiations of the actual world. The laws in these worlds may be precise analogues to Coulomb's law in the sense that they relate different bare universals in precisely the same ways. But on Armstrongís view, the laws will be different at transubstantiation worlds in virtue of having different bare universals as their relata.
Finally, I want to offer a new argument against the contingent nomic relations view. It is hard to see how nomic relations could be contingent on a Platonist view of properties and relations. Laws involve relations between properties and Platonism seems committed to taking these relations to hold of necessity. For the Platonist, contingency is entirely a matter of what properties and relations are instantiated by what spatio-temporal bound entities. Relations that hold exclusively among properties and relations are not contingent upon the way things are in the spatio-temporal realm. And there is nothing else for such relations to be contingent upon. So, for the Platonist, relations among universals must hold of necessity. Hence, in-so-far as laws are held to involve relations that hold exclusively among other universals, the Platonist must understand laws as involving nomic relations that hold of necessity. One might say that Platonismís commitment to necessary nomic relations speaks against Platonism. This is fair enough. But this argument is weakened by whatever independent reasons there are for preferring necessary nomic relations. We have just considered two independent arguments against taking nomic relations between properties to hold contingently. And in the remainder of this paper I will develop and defend an entirely satisfactory view of laws as involving necessary nomic relations. If this project is successful, then the argument from contingent nomic relations against Platonism is quite weak.
The contrapositive of Platonismís commitment to necessary nomic relations is that views about laws that take nomic relations to hold between properties contingently are committed to the falsity of Platonism about universals. While Platonism has its shortcomings, mainly concerning how we should understand the special relation of instantiation, no view about universals is entirely satisfying. Contingent nomic relations beg the question against the possibility that Platonism is right. Because I see Platonism as a viable contender among views about the nature of universals, I think this does speak strongly against contingent nomic relations.
So we have these three arguments against the view that laws are contingent nomic relations between universals. Because Platonism has a limited, or I prefer to say "exclusive", following, the argument from the viability of Platonism about properties and relations is the easiest to overlook. Still, I think this argument is quite cogent. I also think the argument from global transubstantiation is a cogent one. One could perhaps tolerate the proliferation of possibilities and the counterintuitive consequent that the laws differ at global transubstantiations. But I think we would need good reason to cling to a view with consequences this unsavory. As we develop the view that laws are necessarily true analyses of dispositions and consider how potential objections to the view can be answered, I think it will become clear that we lack adequate grounds for tolerating a view of laws that allows for global transubstantiations. The concern about the modal status of laws I take to be more serious yet. The contingent nomic relations theorist owes us some account of our apparently conflicting modal intuitions about laws and I see no prospects for doing so in a non-question begging manner. However, as we will see shortly, the view that laws are necessarily true analyses of dispositions that have the status of lawhood contingent upon the instantiation of the analysandum handles our modal intuitions about laws quite well. I will now turn to developing this proposal.
Laws as Analyses of Dispositions
Ruling out the possibility of global transubstantiation requires that properties have their causal powers essentially. And this leads to the general view of laws as characterizing the essential causal powers of properties. My focus here will be on causal laws. Alan Chalmers notes that some laws, conservation laws for instance, cannot be straightforwardly treated as analyses of dispositions. Brian Ellis takes worlds to belong to natural kinds and proposes to handle such laws as expressing essential properties of the natural kind a world belongs to. Chalmer's sees no need to follow Ellis here and takes the non-conformism of conservation laws to be "interesting, rather than worrying." Chalmers continues, "I do not see why all the generalizations fundamental to science should be of the same kind." But Chalmers endorses the view that causal laws are best viewed as accounts of the essential nature of dispositional properties. That conservation laws and other non-causal laws analyze properties of the world as a whole strikes me as a plausible generalization of the view that laws are analyses of properties. But it will be enough here to make the case for causal laws.
I propose that causal laws are analyses of dispositions. In spelling out this view, I will first say a bit about how I understand analysis. Then I will discuss the nature of dispositions. Next I will illustrate the view with the case of Coulombís law. And finally I will consider some potential objections.
The view of analysis to be employed here is the view developed in Jeff Kingís What is a Philosophical Analysis. An analysis, according to King, is an account of the nature of a complex property or relation in terms of its structure and simpler component properties and relations. The object of analysis, the analysandum, is a property or relation that exists independent of the mind or language. This allows us to account for how analyses can be informative. We have some grasp on the nature of many properties and relations through our acquaintance with their instances. But this can leave us far short of an adequate understanding of their specific natures. Proposed analyses are propositional conjectures about the nature of properties and relations. These conjectures can be tested against what we already grasp through our prior acquaintance with the property, as when we evaluate philosophical analyses from the armchair. Or, where we are concerned with the nature of a property we are acquainted with through our empirical experience of the world, we may test a proposed analysis against evidence obtained in the field or the laboratory. Kingís view of analysis does not limit knowledge of analyses to the realm of a priori philosophizing.
Proposed analyses of dispositions can be given in the following form:
(1) ("x)(Px iff Cx)
In an analysis of a property given in orthodox form, the predicate to the left of "iff" will express the analysandum, the property that is the object of analysis. The predicate to the right of "iff" will be a complex expression having only x free which includes predicates expressing properties and relations that are components of the analysandum. The analyzing predicate to the right of "iff" does not express the same property as the predicate to the left. But it can be said to "represent" the analysandum by having elements that express properties and relations constitutive of the analysandum and by representing those component properties and relations as standing in a complex relation that reveals some of the structure of the analysandum. That structure revealing relation is given in the syntax of the analyzing predicate. So, for instance, we can analyze the property of being a bachelor as follows:
(2) x is a bachelor iff x is adult, male, human and unmarried.
Here we have an account of the complex property of being a bachelor in terms of the component properties of being adult, being male, being human and being unmarried. Further, the syntax of the analysis reveals the structure of these components in the complex analysandum. Specifically, it shows the analysandum to consist of these four properties structured by a four place conjunctive relation. Not every necessarily true bi-conditional expresses an analysis. Again, the further condition is that the complex predicate to the right of "iff" contains terms that express properties and relations that are components of the complex analysandum, and the syntax of that predicate represents the structure of those component properties and relations in the complex analysandum. Now let us consider the form of an analysis of a disposition.
I take a disposition to be a relational property of having some distinct causal base property such that a manifestation of the disposition would be produced were its precipitating conditions to obtain. This view follows Elizabeth Prior, Robert Pargetter and Frank Jackson who propose that if dispositional predicates express properties, then "the property of being fragile will be identical with the property of having a property or property-complex (causal basis) responsible for breaking (in the right way) on dropping." A causal base for a disposition is any property that has the causal power to produce a manifestation of the disposition given the obtaining of the dispositionís precipitating conditions. On this account, a disposition is not identical with its causal base, as Armstrong would have it. Rather, the disposition is a relational property had by a thing when it instantiates an appropriate causal base property. As Prior, Pargetter and Jackson argue such relational dispositions are themselves causally impotent. Causal powers are had by the causal bases of dispositions. And a disposition might have any number of possible or actual causal bases. At this superficial level, we can offer the following schema for analyses of dispositions.
(3) Dv iff ($X)(Xv and CX)
This is a second order formulation with the existential quantifier ranging over properties. In (3), C is the property of being a causal base for the disposition D. So, for instance, a thing is soluble in water iff it instantiates a causal base property for solubility in water. (3) tells us that a disposition is a relational property of having some causal base property. A more complete description of the logical form of an analysis of a disposition will say something about what it is for a property to be a causal base for a disposition.
A property is a causal base for a disposition if instantiating it in conjunction with the precipitating conditions for the disposition would cause a manifestation of the disposition. This account of what it is for a property to be a causal base for a disposition involves a relation of counterfactual dependence between properties; call it R*. R* holds if and only if it is the case that the instantiation of X in conjunction with an instance of P constitutes a sufficient condition for causing an instance of M. A property X is a causal base for a disposition to produce a manifestation M under precipitating conditions P if and only if R*XPM. So, on this account, the logical form of a conditional analysis of a single track disposition D to M if P will be
(4) ("v)(Dv iff ($X)(Xv and R*XPM))
Of course many dispositions are multi-track dispositions. That is, they are dispositions to produce one or another of a range of manifestations depending on which of a range of precipitating conditions obtain. To capture this, we can replace R*XPM in (4) with a suitable conjunction of R* relations fixed by the various possible precipitating conditions and their manifestations.
I will illustrate the proposed view with the case of Coulomb's Law. Coulomb's law characterizes a fundamental force of mutual attraction or repulsion between two bodies as a function of their electromagnetic charge, the distance between the bodies and a certain property of the medium separating those bodies. On the proposed view, we take this force of attraction or repulsion to be the manifestation of a disposition of positive or negative charge. Charge is the disposition partially analyzed by Coulomb's law. A more explicit rendering of this account requires that we explain Coulomb's law in more detail. Coulomb's law is expressed mathematically as follows:
(5) F = KQ1Q2/r2
This law represents a force F between two point charges Q1 and Q2 as directly proportional to the magnitude of those charges and inversely proportional to the distance r between them. The value of K depends on a property, called the permittivity, of the medium separating Q1 and Q2.
On the view of laws I propose, to be in a state of charge is to instantiate a complex multi-track disposition to produce a range of manifestations under a range of circumstances. Coulomb's law provides a partial analysis of this complex disposition. For a body to have a charge of 1, for instance, is in part for it to be disposed to manifest a certain force if separated from another body with a certain charge, by a certain distance in a medium of a certain permittivity and to manifest a different force if the permittivity of the medium differs or if the charge of the second body or its distance from the first differs. Coulomb's law, then, characterizes a very complex disposition of charged bodies. It is a multi-track disposition having as components specific dispositions to manifest specific forces of attraction or repulsion of varying magnitudes depending on the specific magnitudes of the precipitating conditions: the charge of a second body, the distance separating the two bodies and the permittivity of the medium in which their instances exist.
Coulomb's law characterizes a multi-track disposition of point charges to exert forces of mutual attraction or repulsion on other point charges. As such it analyzes a complex multitrack disposition of instances of charge. But it does not provide a complete analysis of charge dispositions. I have suggested that Coulomb's law is a partial analysis of charge. It is a partial analysis of charge because being in a state of charge is not merely a disposition to be attracted to or repelled from other individual instances of charge. Rather, what we find in the world are electrically charged bodies interacting with many other bodies simultaneously. Charges manifest in different forces under these conditions. The force manifested in the behavior of one charged body in the presence of more than one other charged body will be the vector sum of the "component forces" due to the charges of each of the other bodies. Talk of "component forces" is convenient in that it allows us to utilize Coulomb's law in vector analyses of the net forces. But we need not and should not posit the component forces as real phenomenon. The only forces actually manifested in this kind of case are the net forces exerted on the charged bodies. Dispositions to exert these forces are not characterized by Coulomb's law alone. Rather, Coulomb's law characterizes the disposition of charge only with respect to other individual instances of charge. The actual disposition of charge is more complex in that it also involves dispositions to manifest forces in the presence of multiple instances of charge, and when subjected to other forces as well (e.g. gravity, weak and strong).
In light of this, it is easy to see how Cartwright comes to the conclusion that the laws of nature lie. If we take laws to be reports of regularities, then paradigm laws, like Coulombís law, turn out to be false as generalizations and may even fail to describe any actual occurrences. We are not driven to the problematic conclusion that laws are false if we take laws to describe potentialities that are essential aspects of the properties of things rather than to report regularities among events.
In taking laws to be analyses of dispositions I propose that we regard the truth of laws as modally on par with analyses generally. That is, I propose that we take them to be metaphysically necessary truths. What difference there is between causal laws and other kinds of analyses is not modal, but spatio-temporal. An analysis of bachelorhood tells us that instantiation of one property, bachelorhood, entails the simultaneous instantiation of other properties, being male, adult and unmarried. An analysis of a disposition, on the other hand, tells us that instantiation of one complex of properties, a disposition and its precipitating conditions, entails the subsequent instantiation of another.
We do not regard every analysis of an instantiated disposition as a law of nature. There are fragile things. But we cite no law when we assert that a thing is fragile if and only if, if it were suitably knocked about it would break. It is only analyses of relatively fundamental dispositions that we want to count as laws. For a disposition to be fundamental in the sense I propose is not necessarily for it to have a simple causal base. I donít think any disposition requires a simple causal base. But some dispositions are fundamental in the sense of being the end of an explanatory line. I take no stance on just what dispositions ought to be regarded as explanatorily fundamental or specifically why these ought to be regarded as such. But we can offer a variety of examples of dispositions that appear to be fundamental in this explanatory sense. In psychology, complex dispositional properties such as personality types, character states and mental states are fundamental in this explanatory sense. Laws of organic chemistry include analyses of the dispositions of enzymes to break down carbohydrates or proteins. Darwinís theory of evolution by natural selection might best be thought of as an analysis of fitness as a propensity to reproduce. For us, lines of explanation end with analyses of these sorts of dispositions. The task of determining which dispositions are fundamental in the relevant sense is a further project I will not take up here. But the view that laws are analyses of fundamental dispositions should not be taken to beg any questions against the anti-reductionist.
Objections and Replies
A variety of potential objections to the proposed view of causal laws as analyses of dispositions will have to be addressed. I suspect that the contingency of laws is too readily embraced for fear that necessary laws would violate certain intuitions about how things might have been. In fact I think the modal intuitions commonly thought to be at stake can be nicely accommodated on the proposed view. I have briefly suggested how previously. I will say more below. It is also alleged that dispositions are explanatorily impotent. I will have to explain how analyses of dispositions can play the explanatory role that laws play in science. These concerns will be addressed shortly. But first I will consider the epistemological status of laws as necessarily true analyses.
The Epistemological Status of Laws as Analyses
One might think the view that laws are necessary must be false because laws are known a-posteriori. This argument against necessary laws is offered by John Carrol. Carrol does mention that Kripke has made a case for a-posteriori necessities. But as Carrol sees it, "over twenty years later, Kripke's so-called discovery is still sufficiently controversial to make me reluctant to dismiss the epistemological worry." I will not rehearse Kripke's case for a-posteriori necessities. But I do find it sufficiently compelling to dismiss the epistemological worry that laws must be contingent because they are known a-posteriori. But what is called for here is not merely the dismissing of epistemological worries, but some positive account of how laws as necessarily true analyses of properties can be known a-posteriori.
Even if we grant Kripkeís case for a-posteriori necessities, we might balk at the notion of knowing analyses a-posteriori. Analytic claims are traditionally characterized as claims that are true in virtue of meaning. Where linguistic competence is assumed to entail complete understanding of meaning, analytic claims, including analyses, will generally be regarded as knowable a-priori. On this view one need only examine the contents of one's mind as a competent speaker to find adequate grounds for the truth of analytic claims. This is hardly how we discover that a scientific hypothesis is a law. But we have already rejected the assumptions that lead to this view. The rough intuition that analyses are known a-priori is typically held in the absence of any specific account of analysis or meaning. But we have taken positions on these matters. The meaning of a predicate is just the property or relation it expresses. Analyses are accounts of the natures of such properties. Given the mind independent status of properties and relations, our epistemic connection to them is left open. That we can competently use a word to express a certain property is no guarantee that we fully understand the nature of that property. We can have acquaintance with properties through their instances and still lack detailed knowledge of their nature. And we can learn more about the nature of properties instantiated in the world through our experience of the world.
We may have acquaintance with some property or relation through our experience of the world without knowing the constituents or structure of that property. We are acquainted with the property of being water through our experience of stuff that has that property. But this experience does not inform us about the properties and relations that are constitutive of the property of being water. We can and have employed empirical methods in testing proposed analyses of the property of being water and we have successfully confirmed that it is H2O. On the proposed account of analysis, we can say both that analyses are true in virtue of meaning and make sense of empirical inquiry into the nature of what is meant.
Something similar can be said in the case of analyses of more characteristically philosophical properties and relations as well. Even though we cannot give a detailed analysis of what it is to know that something is the case, we do grasp what it is to know that something is the case. I think I grasp the nature of knowledge because I readily attribute knowledge of this or that proposition to various individuals, occasionally including myself. Also, I recognize counterexamples to proposed analyses of knowledge, etc. Nevertheless, giving a detailed account of the nature of knowledge is not a trivial matter of stating something I already know as a competent speaker of the language. Rather, it is the end product of exercising a philosophical method of rational inquiry. A proposed analysis is offered. We then test it against various possible cases looking for counterexamples or other flaws. We then refine our analysis in light of any discovered problems so as to more accurately explain the nature of the property or relation we grasp, but don't fully understand. The method is not so different from that of the natural sciences. Perhaps the difference lies mainly in what counts as evidence. In the natural sciences, what typically counts as evidence is, in varying degrees, our sensory experience of the world. In the case of more characteristically philosophical analyses intuition, rational insight, or coherence with other analytic commitments, bears more heavily on the issue.
Some might doubt whether philosophical intuitions carry any weight as evidence. Kripke says, "I think [intuitive content] is very heavy evidence in favor of anything, myself. I really don't know, in a way, what more conclusive evidence one can have about anything, ultimately speaking." Whether or not one is sympathetic to Kripke on this point, given the theory ladenness of observation, it does not appear that what counts as evidence in the empirical sciences is entirely divorced from our intuitions. No less so than in philosophy, every judgment about a proposed hypothesis in the natural sciences involves bodies of background theory. I donít think there is any way to avoid recognizing some role for intuition, or rational insight, in evaluating the evidence in either the natural sciences or philosophy. But what matters here is that we describe some role for empirical inquiry in evaluating scientific hypotheses where these are taken to be analyses of properties and relations.
I take it that every clear, consistent proposed analysis analyzes some property or relation. The conditions given in a proposed analysis may be inconsistent, ambiguous or obscure. In this case we should say that the proposed analysis fails to analyze any property. But when we reject an analysis it is not necessarily because the conditions given fail to analyze any property at all. Often we reject analyses because the conditions given in the analysis fail to analyze the property we are interested in and intend to be the object of our analysis. We could give the property analyzed by the proposed analysis a name and substitute that name for the property term identifying our intended analysandum and thereby express a necessarily true analysis of a more or less uninteresting property or relation. For example, since Gettier, we reject the analysis of knowledge as true justified belief. But give true justified belief the name "schmowledge" and "a person schmows that P if and only if she has a true justified belief that P" expresses a necessarily true analysis of the relation of schmowing. Of course, since we no longer take knowing to be schmowing this is an analysis of a relation that is no longer very interesting to philosophers. Many bona fide analyses are relatively uninteresting to philosophers just because they are not analyses of the interesting properties and relations we take to be instantiated in the world. Likewise in the natural sciences, we can take any clear coherent hypothesis to analyze some property or relation. But only those hypotheses that analyze properties and relations we have grounds for thinking to be instantiated in our world will help to explain the nature of our world. The task of empirical inquiry is to determine whether or not a proposed hypothesis analyzes the specific property we are acquainted with through our experience of its instances in our world. We examine the world to see if the properties we find in the world are in fact the ones analyzed by our proposed property analyses. If they are not, we reject the analysis, not because it fails as a necessarily true analysis of some property, but because it is not an analysis of the specific property we find instantiated in the world. So for instance, a proposed analysis of an instantiated disposition may lead us to expect a certain manifestation of that disposition under certain empirically observable circumstances. If the disposition fails to manifest in accordance with our expectation based on the proposed analysis, then we have empirical grounds for thinking the proposed analysis fails to adequately analyze the instantiated disposition. There is nothing new here. We can regard this as akin to an application of Popperís method of conjecture and refutation to conjectures about the essential nature of the properties we find instantiated in the world. Though I am not convinced that mere corroboration is the best we can hope for from our empirical testing of proposed property analyses. Unlike Popper, Iím inclined to recognize a legitimate role for abduction in providing positive support for scientific hypotheses. But my only aim here is to identify some role for empirical inquiry in evaluating scientific hypotheses. And we have done this much.
The Alleged Intuition that Laws are Contingent
We have the intuition that things might have been different than they are. I think our intuitions about how things might have been deserve to be respected. And I think that the proposed view of laws as necessarily true analyses of instantiated properties can elegantly accommodate our modal intuitions. Suppose that the laws of nature are necessary and that causes could not have had different effects. It does not follow that things could not have been different from the way they are. For one thing, neither of these suppositions presupposes universal causation; the thesis that every event has a cause (in the sense of a sufficient condition). Some sets of laws might entail universal causation. But we can also imagine a world where some types of events are governed by laws and others occur randomly. For instance, a relatively simple world might contain only events of types P and Q. In this world it might be a law that P events cause Q events while the P events themselves are mere random occurrences not governed by laws. The possibility of such a world is independent of whether or not the laws are necessary truths. So, the view that laws are necessary doesn't presuppose universal causation. Given this, even if the laws are necessary truths, at any point in the causal history of a world where the laws are not deterministic, improbable events might have necessitated that things thereafter follow a different course than they in fact have. But the thesis of universal causation has a following. So, let us suppose in addition that universal causation holds.
Necessary laws and universal causation do not entail that things could not have been different. The initial state of the world, assuming for the moment that it had one, might have been different. Had the initial state of the world been different, every subsequent state of the world would be different as well. We might suppose that the world's being in a different initial state is just a matter of its consisting of more or less stuff or that stuff being differently arranged. But the initial state of the world might also have differed with respect to the properties instantiated by its stuff. Further, the supposition of an initial state of the world only serves to make the possibility of differing arrangements of matter or differing properties being had by that matter easier to grasp. It is not essential here. An infinitely old world might have always had differently arranged matter instantiating different properties. So, the intuition that things might have been different is not at stake in considering whether causes could have had different effects or whether or not the laws of nature are necessary.
Perhaps we also have the intuition that the world might have been just as it is up to a certain point in time and then diverged in some way. If we assume determinism and universal causation, then this intuition proves false whether laws are contingent or necessary. The supposition that the laws of nature are contingent allows that they might have been different. But it does not allow that the laws of nature are mutable. If, on the other hand, universal causation is rejected, then things might have been just as they are up to a certain point in time and then diverged regardless of whether laws are necessary or contingent. So, the intuition that things might have been as they are up to a certain time and then diverged is also not at stake in the current discussion. Whether laws are necessary or not, determinism rules out divergence and indeterminism allows it.
Perhaps a sufficiently subtle difference in the arrangement of stuff or in the properties instantiated or in the laws of nature could have yielded a world that is empirically indistinguishable from ours up to a certain point but diverging thereafter. That is, the world might have been different in subtle ways that lurked hidden from us up to a certain time. But the apparent similarity of such a world's earlier history is just that, merely apparent. On either view, that the laws of nature are contingent, or that they are necessary, the actual differences would have obtained from the start.
John Carrol offers another reason for holding that the laws of nature are contingent. It is just that "it is easy to imagine the laws of one possible world being false in another." This argument is perhaps just a special case of the general intuition just discussed that things might have been different. But there we were considering the possibility that "things" might have been different. "Things" might include events, things, states of affairs, etc. But the intuition that laws specifically might have been false has not yet been explicitly addressed. However, I don't think we actually have the intuition that the laws are contingent truths. The proposed view takes laws to be necessarily true property analyses which have the further property of law-hood contingent upon the analyzed disposition actually being instantiated. I would suggest that the intuition that Carrol appeals to is not the intuition that the laws of nature might have been false, but the correct intuition that things in the world might have instantiated different dispositions. This intuition is readily accommodated on the proposed view.
To elaborate on this point, let us take Newtonian gravitational mass (NG mass) to be a disposition to manifest an inverse square force in accordance with Newton's law of universal gravitation. On this supposition, Newton's law of universal gravitation is a necessarily true analysis of NG mass. It follows that we cannot coherently imagine a world in which Newton's law of universal gravitation is false. That is, we cannot imagine a world in which NG massive bodies fail to exert an inverse square force in accordance with Newton's law. However, the view here offered does allow that things have properties similar to, but distinct from NG mass. In fact things do. This does not render Newton's law false as an analysis of NG mass; just false as an analysis of mass, that property of mutual attraction that is in fact instantiated by all bodies. Newton's law, though we still call it a law, isn't a law of nature; not because it isn't a true analysis of some property similar to mass, but because it is an analysis of a mass like property that is not instantiated by actual bodies. Conceivability arguments can only support the contingency of laws of nature if they presuppose that laws represent relations between non-dispositional properties. But this merely begs the question against necessarily true laws. In fact, our intuitions about how things could have been can be comfortably accommodated on the view that laws are necessarily true analyses of dispositions.
The Alleged Explanatory Impotence of Dispositions
One might object to the proposed view of laws as analyses of fundamental dispositions on the grounds that dispositions are explanatorily impotent. We have, for instance, the familiar case of Moliere's joke. We give no explanation of why ingesting opium causes a person to sleep by attributing to opium the dormative virtue, a disposition to induce sleep when ingested. How then can laws, conceived of as analyses of dispositions, perform the explanatory work we take laws to perform. In fact, I think a closer inspection of the precise respects in which dispositions are and are not explanatorily impotent will reveal analyses of dispositions to be very well suited for the explanatory role of laws.
Appeals to dispositions are explanatorily impotent in certain respects. That opium has the dormative virtue does not explain why opium causes people to fall asleep. The question "why does ingesting opium cause people to fall asleep?" presupposes that ingesting opium has the dormative virtue and asks what accounts for its having this disposition. Attributing the dormative virtue to opium fails to address this question. But attributing the dormative virtue to a substance does have explanatory value with respect to other questions. For instance, that Curious George ingested a substance with the dormative virtue can explain why Curious George is asleep. He might have fallen asleep because he was sleepy. But appealing to the dormative virtue of a substance Curious George has ingested identifies his being asleep as the manifestation of a particular disposition as opposed to some other possible cause.
The view that charge is a disposition analyzed by Coulomb's law accords well with the foregoing intuitions about explanatory value. Suppose we take charge to be a disposition to behave according to Coulomb's law. In this case, that electrons have charge will be explanatorily impotent with respect to the question "Why do electrons behave in accordance with Coulomb's law?" Again, the question presupposes that things have a disposition to behave in accordance with Coulomb's law and asks for some account of why this is the case. But explanatory impotence in this regard fits our intuitions about the explanatory value of laws quite well. Science may tell us that electrons have a disposition to behave in accordance with Coulomb's law. In so doing it tells us that things have charge. But science does not tell us why electrons have charge. Or at least not yet. But even if a grand unified theory ultimately does explain why things have charge in terms of some single underlying force, it will not be Coulomb's law that is offered as an account of why things have charge.
If we take charge to be a fundamental force, we accept certain facts as basic and reject the relevance of certain questions regarding those basic facts. In so far as we take charge to be a fundamental force, we accept things having charge as the end of the explanatory line and we reject the question "Why do bodies have charge?" In taking charge to be just a disposition to behave in accordance with Coulomb's law we also reject the question "Why do bodies with charge behave in accordance with Coulomb's law?" I see no significant cost in accepting this. That bodies have charge, in conjunction with various other laws, still retains ample explanatory power with respect to questions like "Why does the flashlight light up?" or "Why does the voltmeter register?"
In addressing the foregoing potential objections to the view that causal laws are analyses of dispositions, we have gone some ways towards saying how laws are known, how laws explain, and how to accommodate our seemingly conflicting modal intuitions about laws. In light of the promising avenues open for addressing these core issues and answering the most significant potential objections to the proposed view, I think we have insufficient grounds for tolerating global transubstantiations and concerns about the modal status of laws associated with the view that laws are contingent nomic relations between universals. Therefore, I conclude that nomic relations are necessary, properties have their causal powers essentially, and causal laws are analyses of dispositions.
Armstrong, D. M. What is a Law of Nature. Cambridge University Press, 1983.
Bigelow, John. "Scientific Ellisianism." In Causation and the Laws of Nature. ed. H. Sankey, 45-59. Dordrect: Kluwer, 1999.
Bird, Alexander. "The Ultimate Argument Agaist Armstrongís Contingent Necessitation View of Laws." Analysis (forthcoming)
Carrol, John. "The Humean Tradition." The Philosophical Review 99 (1990): 185-219.
Carrol, John. Laws of Nature. Cambridge: Cambridge University Press, 1994.
Cartwright, Nancy. How the Laws of Physics Lie. Oxford University Press, 1983
Chalmers, Alan. "Making Sense of Laws of Physics." in Causation and the Laws of Nature. ed. H. Sankey, 3-18. Dordrect: Kluwer, 1999.
Dretske, Fred. "The Laws of Nature." Philosophy of Science, 44 (1977): 248-68.
Ellis, Brian. Scientific Essentialism. Cambridge: Cambridge University Press, 2001.
Ellis, Brian, and Caroline Lierse. "Dispositional Essentialism." Australasian Journal of Philosophy 72 (1994): 27-45.
Goodman, Nelson. Fact Fiction and Forecast. Cambridge: Harvard University Press, 1955.
King, Jeffery. "What is a Philosophical Analysis?" Philosophical Studies 90 (1998): 155-179.
King, Jeffrey. "On the Possibility of Correct Apparently Circular Dispositional Analyses." Philosophical Studies 98 (2000): 257-178.
Kneale, W. C. "Natural Laws and Contrary-to-fact Conditionals." Analysis 10 (1950).
Kripke, Saul. Naming and Necessity. Cambridge, Massachusetts: Harvard University Press, 1972.
Lewis, David. Counterfactuals. Cambridge: Harvard University Press, 1973.
Lewis, David. "New Work for a Theory of Universals." Australasian Journal of Philosophy. 61 (1983): 343-377.
Martin, C. B. "Dispositions and Conditionals." The Philosophical Quarterly. 44 (1994): 1-8.
Mills, Susan K. and John H. Beatty. "The Propensity Interpretation of Fitness." In Conceptual Issues in Evolutionary Biology, ed Elliot Sober, 3-24. Cambridge: The MIT Press, 1997.
Prior, Elizabeth, Robert Pargetter and Frank Jackson. "Three Theses about Dispositions." American Philosophical Quarterly 19, 3 (July, 1982): 251-57.
Shoemaker, Sydney. "Causality and Properties." In Time and Cause, ed. Peter van Inwagen, 109-135. Dordrecht: Reidel, 1980.
Swoyer, Chris. "The Nature of Causal Laws." Australasian Journal of Philosophy 60 (1982): 203-23.
Tooley, Michael. "The Nature of Laws." Canadian Journal of Philosophy 7 (1977): 667-98.
Van Fraassen, Bas. Laws and Symmetry, Oxford: Clarendon Press 1989.