Dispositions and essences.
Université Paris XII et Institut Jean-Nicod (CNRS-UMR 8129).
(Colloque “Dispositions et pouvoirs causaux”, Paris X-ENS Ulm, septembre 2002)
From some time now, dispositions have no longer been viewed as ethereal or occult powers that have a pre-scientific status, threats or ghostly forces in need of redemption, mere promissory notes, some lazy or inaccurate way of talking that no self-respecting scientist should ever use. The pregnant spinsters have now acquired the respectable status of unmarried mothers, up to the point that they do lead a life of their own. Indeed, not only are they viewed as possible accidental properties of things: they are taken as essential properties of things in nature. Even more, for some philosophers, all things in nature are essentially dispositional. I have tried elsewhere to sketch the historical and philosophical reasons why there might have been such a revolution from pure elimination (as may be found under various forms in Boyle, Quine, Goodman, or Ryle) to inflation (Ian Thompson, Rom Harré, Nancy Cartwright, Karl Popper, Hugh Mellor, Simon Blackburn) as regards dispositions, powers or capacities (with, in some cases, their idealistic consequences). In what follows, I would like to concentrate on some less extreme versions of dispositional essentialism such as have been proposed by some authors, especially Brian Ellis, and in an even less extreme version, I think, by Stephen Mumford. I shall begin by presenting Ellis’s main lines of argument and then try to see whether some of the difficulties raised by his account and the answers suggested by Mumford are satisfactory, especially as far as a dispositionalist account of laws is concerned. Favoring myself some form of dispositional realism rather than essentialism, I shall finally less present here some arguments in favor of such a position than merely make some suggestions as to what seem to me the major difficulties which any kind of dispositionalism should be ready to face.
1. Brian Ellis’s conception of dispositional essentialism : the main arguments.
Ellis’s conception of dispositional essentialism (which he first exposed in an article written with Caroline Lierse in 1994) is part and parcel of the more general view he now entitles scientific essentialism, which can be summarized in three basic theses :
1) Scientific essentialism deals with natural kinds such as events and processes and not only with objects and substances. According to Ellis, “the world is structured into hierarchies of natural kinds of objects and processes : it is not an amorphous world on which we must somehow impose our own system of categories. There is a pre-existing grid of objective categories, and it is the aim of natural science to reveal and describe them”. Scientific essentialism is concerned with natural kinds which range over events and processes as well as with the more traditional sorts which range only over objects or substances. According to scientific essentialism, the most general laws of nature describe the essential properties of these global kinds, and therefore hold necessarily of all objects, events and processes: “The law of conservation of energy, for example, states that every event or process of this global kind is one that is intrinsically conservative of energy. Hence, any event which was not intrinsically conservative of energy could not be one of a kind that would occur in our world. The laws we think of as causal laws are generally more specific in their direct application. The laws of electromagnetism, for example, apply directly to all electromagnetic radiation, and hold necessarily of all such radiation. Therefore, if there is any radiation which is not propagated according to these laws, it cannot possibly be electromagnetic”.
2) Secondly, scientific essentialism claims that “the essential properties of the most fundamental kinds of things are not just the passive primary qualities of classical mechanism, but also include a number of causal powers, capacities and propensities — powers to act, and powers to interact”, namely properties which are essentially dispositional in nature, implying dispositions to act and react in various ways, depending on the circumstances. Traditionally, such properties have been thought to be ontologically dependent on underlying categorical (i.e. non dispositional) properties and on the laws of nature. According to the new essentialism, however, at least some of these dispositional properties are fundamental, and not dependent upon any other properties In other words (one will note the Aristotelian and/or Leibnizian flavor), the basic things in the world are essentially active and dynamic. “They are not just passive objects obeying blindly the commands of God, as most seventeenth and eigtheenth Century philosophers believed, a world of things having only the attributes of extension and impenetrability, as Descartes’s and Locke’s worlds were; rather it is a world in which things have their own internal dynamics, which are essential to their natures, and which are determinative of their behaviour”. In that respect, “all things are essentially active and reactive: at the most basic level, what they are intrinsically disposed to do is what makes them the kinds of things they are. Things of given kinds must always be disposed to behave in certain kinds of ways, just by virtue of being things of these kinds. Their identities as members of these kinds depend on their being so disposed to act”. Hence,” the real defining characteristics of the most fundamental kinds of things that we know about, namely, thing like protons and electrons, would all appear to lie in their laws of interaction. Things of these kinds would appear to have no real defining characteristics at all apart from their causal roles. A proton, for example, might be defined (by way of real definition) as any particle which behaves as protons do. For no proton could possibly fail to behave in these ways, and no particle other than a proton could possibly imitate this behaviour. Its identity, qua proton, might thus be defined by its causal role. Similarly, one might say that an electron is, by real definition, any particle for which the laws of interaction are precisely those of electrons. Nothing other than an electron could possibly behave in such a way, and whatever does behave in this way has to be an electron”.
3) Hence a third thesis: the laws concerning the behaviour of protons, and their interactions cannot be just accidental, i.e. laws which could well have been otherwise. On the contrary, it is essential to the nature of the proton that it should be disposed to interact with things of various kinds precisely as it does. The protons’s causal powers, capacities and propensities are not just amongst the accidental properties of protons, which depend on what the laws of nature happen to be, but amongst their essential properties, without which there would be no protons, and which protons could not lose without ceasing to exist.
Accordingly, “the traditional view that the laws of particle physics are imposed on intrinsically passive things which have kind identities which are independent of the laws of their behaviour is thus implausible from the point of view of modern science. Essentialism is a much more plausible position to take”.
As Brian Ellis observes, the claim that the world is structured into hierarchies of natural kinds of objects and so on, could in principle be accepted by philosophers who were otherwise sympathetic to mechanism : things of different natural kinds, they might say, are just things made up of different basic ingredients, or of the same ingredients, but put together in different ways, although there is nothing in their natures which requires that they should behave in one way rather than another. How they are disposed to behave depends on what the laws of nature happen to be. Now it is precisely such a contingency thesis or Humean view of the laws of nature that Ellis denies. First, the relationship of dependence between the causal powers and the laws of nature is the other way round: the laws depend on the properties, not the properties on the laws; second implication: the laws of nature are metaphysically necessary, and hence true in all possible worlds. That is, “it must be metaphysically impossible for things, constitued as they are, to behave other than in accordance with the laws of nature. Even God (assuming Him to exist and be all powerful) couldn’t make them behave contrary to their natures. He might change their natures, perhaps, so that they might become, or be replaced by, different kinds of things. But there is no possible world in which things, constituted as they are, could behave any differently. For them to behave differently, they would have to be or become things of different kinds, or be made up of things of different kinds”. Hence laws of nature are both descriptive and prescriptive: “What science observes and codifies are the manifestations of these dispositions. Hence, laws which describe how dispositional properties act will, at the same time, tell us what things which have these properties essentially must do in virtue of being the kinds of things they are”. The natural dispositions are the truthmakers for these laws.
2. Mumford’s dispositional essentialism.
Even if Mumford characterizes his own position as being mainly a functionalist view of dispositions coupled with a neutral monistic ontology, at several places, especially in his comment on Ellis & Lierse’s paper as well as in the last chapter of his book Dispositions, he admits that he endorses dispositional essentialism for certain basic kinds and agrees with many points raised by Ellis and Lierse: only, he takes them to task for the ontology they deem necessary for their position.
So, let me try to spell out what are the main arguments Mumford advances in favor of such dispositional essentialism:
1. First of all, Mumford thinks that “the explanatory value of appeal to dispositions typically resides in them being causally efficacious and being properties”. It means that they cannot be reduced, for example, to a different class of entities such as events or occurrences, and that their criterion of existence is the causal criterion which can be defined in the following way :
“The causal criterion of property existence: for any intrinsic abstract property P, P exists if and only if there are circumstances C in which the instantiations of P have causal consequences”.
2. Ellis and Lierse, at least in their 1994 paper, were very clear that they did not seek to “restore the reputation of dispositions by attacking the status of categorical properties, or by arguing that all properties are basically dispositional, as some philosophers have done”, but mainly to show that “their lowly status was a consequence of their traditional affiliation with an inadequate ontology based on a Humean metaphysic, and a flawed semantics of dispositional terms”(ibid.). So, what they sought to provide was “a more adequate semantics, and an ontologically more satisfactory theory of dispositions – one which allows at least some dispositions to be counted as genuine properties existing in their own right”(ibid.).
Mumford, together with most philosophers trying to rescue dispositions, agrees with the first part of the program: a new semantics for disposition is needed, which in particular should provide an adequate analysis of the relation (which is not one of equivalence, but of irreducibility, between disposition ascriptions and subjunctive conditionals.
3. Again, as Ellis and Lierse, and unlike, for example, Hugh Mellor, who thinks that such properties as triangularity which at first sight look categorical, may be viewed as dispositional, Mumford does not so much attack the Categorical-Dispositional distinction as he tries 1. to explain why it is relevant only as a conceptual (though not a real) distinction between ascriptions (chap. 4), 2. to clarify the confusions attached to the concept “categorical”, 3. to fix some criterion for the distinction, namely the following: both dispositional and categorical properties have causal roles. But “disposition ascriptions are ascriptions of properties that occupy a particular functional role as a matter of conceptual necessity and have particular shape or structure characterizations only a posteriori” whereas “categorical ascriptions are ascriptions of shapes and structures which have particular functional roles only a posteriori”, namely as part of scientific investigation. Indeed, “what is crucial to property monism (the position Mumford adopts) is a justification of the claim that dispositions and their categorical bases are actually the same states of particular things, characterized in two different ways, rather than distinct states in the world”. Which, incidentally means that “the identity conditions for properties are separated from the identity conditions for predicates”. Hence “I can know what it is for x to be soluble though I need not know what it is for x to have the particular molecular structure which is a categorical base of solubility, say, xyz. I need not know which molecular structure is involved or even what a molecular structure is, even though ‘x is soluble’ may be true in virtue of the possession of the same state that makes ‘x has molecular structure xyz’ true”.
4. Again, another argument by which Mumford seems to agree with Ellis’s version of dispositional essentialism is his rejection of the Continuing existence argument raised by categorical realists to justify the need of categorical bases for dispositions. Now the continuing existence is the claim that dispositions have existence in between their manifestations only if they are grounded in categorical properties. Indeed, as Ellis and Lierse hold, dispositions need to be based in reality: “They must at least be properties of real things. Moreover, it is often the case that things have the dispositions they do because of their internal structures; and in all such cases, we may say that the dispositions are grounded in these structures. However, it is not clear that the basis of any given disposition must, or must, ultimately be non-dispositional. For, without begging the question against non-Humeans, it cannot be assumed that the basis of a disposition does not, or does not ultimately, include other dispositions. For example, the dispositions of an object might well depend on the causal powers of its parts, as well as on how these parts are arranged”. So a power could well be grounded in a further power: not all powers need categorical properties. Nevertheless, Mumford is very cautious to distinguish “ordinary” from “ultimate” dispositions. First, because “most dispositions are of the ordinary variety”, so that ultimate dispositions are “limited’ (examples of which would be the dispositions of subatomic particles which apparently have no internal constitution that could explain their behaviour). Second, because the history of science shows that mistakes are possible in this respect: “We cannot be sure, for any putative ungrounded position, whether it is genuinely ungrounded or actually just an ordinary disposition and only thought to be ultimate because of the incomplete state of our physics”. Nonetheless, in terms of explanatory requirements and sound methodology we cannot either rule out their existence a priori. Even more: “The nature of explanation is such that ungrounded dispositions will always have to be posited in order to avoid a regress of explanation and, further, we have every reason, as part of the atomist strategy, to assume that there are genuine ungrounded dispositions. So the function of ungrounded dispositions is to ‘fill the space’ of our process of explanation”(ibid.).
6. But most of all, Mumford agrees with Ellis not only in letting disposition ascriptions play an explanatory role and in conceiving dispositions as units of explanation, but in favoring a dispositionalist account of laws, instead of what he labels the “law view”, namely, the view that laws, conceived as constant conjunctions or natural necessitations of events, are the basic building blocks of explanation. Instead, “the dispositionalists attempts to dispense with laws of nature by grounding natural necessities within the individual instantiated properties themselves. This gives us the model of instantiated properties as real powers to do things. It is also useful to speak of them as enablements or affordances where this conveys the dispositional notion of causal mediation between events. Thus we have natural necessities without commitment to general laws ranging over classes of events. Instead of general necessities, natural necessity occurs at the level of the particular. It is not in virtue of a general law that sugar dissolves when in a liquid, for instance, it is in virtue of a particular state or instantiated property possessed by that sample that it does so”.
In various places, Mumford has, quite convincingly, I think, outlined the advantages offered by such a dispositionalist account of laws over both the Humean supervenience view as most strongly defended by David Lewis and the Dretske-Tooley-Armstrong (DTA) view of laws, which, despite its challenging the Humean view by taking laws to be real things in nature involving necessary connections between properties, still retained some vestiges of the Humean metaphysic.
Now, what are indeed the advantages of seeing laws to be supervenient upon dispositions instead of dispositions being supervenient upon laws?
The problems with some laws (I do not deal here with statistic laws) (such as “all water boils at one hundred degree centigrade or “all ducks have webbed feet”) are well known: the identification of them with universally quantified conditional statements is doomed to failure. The main challenge to regularity accounts of law is to distinguish coïncidental from genuinely lawlike regularities and, secondly, virtually no statements of this form are true. As Nancy Cartwright has argued, laws of nature qua general statements are, for the most part, idealizations and abstractions that should not be regarded as literally true. And the ceteris paribus strategy amounts to triviality.
Getting away from the notion of the statements of laws being general truths, the DTA or “nomic necessitation” version, by construing them as causal relations holding between universals constitutes a progress in so far as it allows realist causal claims that go beyond empirical evidence. But the nomic necessitation view does not explain how nomic necessitation entails the corresponding generalisations – it has to stipulate that it does. Moreover, at least in the case of Armstrong’s conception, according to Mumford, although it deals with exception cases (the “oaken” laws as opposed to the “iron” laws), it too, like Hume’s and Lewis’s accounts, is “committed to reading off the laws from the actual history of events at a world” and is caught up in some form of actualism: “The only existence of the laws is in what particular causal sequences occur, so the laws are determined by the events” (ibid.). Causation holds between universals but it can only do so if it has instantiations standing in the right relation.
Mumford thinks that a right account of laws must reside somewhere “twixt regularity and regulation”, namely between the descriptive regularist view and the theological view concentrating on regulation with laws as God’s prescriptions. In order to qualify as the right interpretation of laws, both somewhat descriptive and prescriptive, viewing these as that “which bind the possible and necessary but not the actual in the natural world at which they apply”, a dispositionalist standpoint seems the most appropriate. For example, instead of construing “all ravens are black”, let us drop the requirement that the conditionals associated with law statements must be universally quantified: let us just say instead “ravens are black” without quantification. Now there is no need for quantification if we understand such a statement as being not explicitly about a numerable quantity of ravens but as being about the normal dispositional colouring of the species. According to Mumford, such a view fits with scientific practice: namely, the scientist finds a typical representative of some species or kind of thing and then, in carefully controlled conditions, finds out some natural dispositional property of that thing. He is not concerned with amassing more and more cases of black ravens, nor will be troubled by the existence of strange cases, such as an albino (the equivalent of C.B. Martin’s electro fink-case). Thus, such a notion of “the natural behaviour of things” supplies us with as much description and regulation as we need for our laws, it gives us a sense of objects having natural governing principles without obliging us to give up contingency. Indeed, Mumford contends, “because of the dispositional force of such governing principles, these dispositions need not be manifested: whether or not they are manifested depends on the contingencies of the world’s history; for instance, on whether the right stimulus conditions are ever realized and whether the correct background conditions are in place”. In the second place, “what the laws are best understood as descriptive of is not actual or possible events but the capacities of things. Thus, the truth of the claim that a fair coin has a 50/50 chance of landing a head or a tail is true not in virtue of the result of any toss or sequence of tosses, but in virtue of the 50/50 propensity the coin has to land head or tail.…The probabilistic law can thus be explained by it being descriptive of an actual disposition and the account also explains the possibility of unrealized laws. The disposition ascription is true of the coin if it is never tested and thus there can be two true but different ascriptions in two worlds that coïncide in all their events”. In the third place, “there is plenty of contingency in these laws: one needs not even appeal to another possible world to illustrate this : the laws of nature could change, gradually or instantaneously. The laws are fixed only by what things (can) do at present. Thus ravens are black now, meaning that it is true of the raven kind that its normal members are dispostionally black, but tomorrow, through a divine intervention, normal ravens may become dispositionally pink. More naturally, over a period of time normal ravens may become grey through evolutionary processes. So such an account leaves open the possibility that even the fundamental laws could change”(ibid.).
So far so good. But are such arguments wholly convincing?
3. Some suggestions about the main difficulties dispositional realism should be ready to face.
Mumford as well as Ellis or other proponents of the redemption of dispositions intend to confer them a real and not merely fictional status. But what kind of reality have dispositions actually gained? In other words, are their respective versions of dispositional essentialim or functionalism realistic enough?
There are a lot of convincing aspects in Mumford’s account but some are also somewhat puzzling. I shall take them in turn.
1)The merits of ontological deflation or “neutrality”: from properties to predicates. It is surely an interesting part of the neutral monistic understanding of dispositions to show how the dispositionality or non dispositionality of a property or state is not a question which is (mainly) grounded in ontology, but is, rather, a matter relative to the predicate with which the property or state is denoted and to the connection between this predicate and the behaviour which is mediated; or again that “it is not a truth of ontology whether a property is dispositional or not; it can only be a truth about concept”. All the same, as both Ellis and Mumford have observed, such a conceptual reading of the issue does not prevent you from being a realist, as Peirce once also noted, who was one of the first philosophers to attach a particular importance to the reality of dispositions:
“Anybody may happen to opine that ‘the’ is a real English word; but that will not constitue him a realist. But if he finds that, whether the word ‘hard’, itself be real or not, the property, the character, the predicate hardness is not invented by men, as the word is, but is really and truly in the hard things and is one in them all, as a description of habit, or behaviour, then, he is a realist”.
So indeed, any correct account of the role and nature of dispositions should start with a semantic account of dispositional predicates, as Hugh Mellor also reminded us, and, in particular, should try to deal with the reasons why dispositional ascriptions might be meaningless (for example, due to finkish, antidote or mimic cases), or why reduction sentences may or may not tell us what “all” dispositional predicates mean. Suppose, for example, that we know all the manifestations of courage: are we going to be able to say what “courageous” means by summing up all the reduction sentences that say what those manifestations are? Or course not: as Peirce insisted on, a disposition is, by essence, irreducibly general and indeterminate, and cannot be reduced to the mere conjunction of its occurrences.
2) Dispositions as properties or how should one understand the Categorical-Dispositional distinction?
But, as Mellor, Ellis or Mumford also insist on, properties are not (or are not given) simply by the meaning of our predicates. Nobody would ever think that the planet Mars is, or is part of, or is defined by the meaning of the “word” Mars which we use to refer to it. On the contrary, what gives consistency to the referential capacity of our predicate , when we use it, is that it takes for granted the existence and the identity of planet Mars. In other words, we want a conditional and non verifunctional statement such as “if x was dropped, it would break” to have a truthmaker. This is why Mellor, following Armstrong, rejects the Rylean and counter intuitive view according to which when a fragile thing a and a non fragile thing b are not dropped, there need not be a factual difference between them. On the contrary, one should say that if a is fragile and b is not, then a and b, whether dropped or not, must differ in some respect, the most obvious difference consisting in the fact that a has the property of being fragile, which b has not.
But how should one explain what that property consists in? To a certain extent, Mumford refuses to commit himself too far.
“The functionalist theory of dispositions states that nature consists of hierarchically ordered levels where at each level there are entities or properties than can be characterized either dispositionally or structurally and whether they are dispositional or structural characterizations depends on their explanatory relations to other entities or properties within the whole of which they are a part”
“Relative to the functional role of causing dissolving when in liquid, a denotation of a property P that has that causal role by conceptual necessity - solubility- is dispositional. Denoted in such a way that does not conceptually necessitate that causal role, perhaps in terms of molecular structure, that same property comes out as non-dispositional. By the argument from the identity of causal role, however, these two denotations are of the same state or property instance”.
In a similar vein, Mellor suggests that properties are neither categorical nor dispositional: they just are.
But this is a bit unsatisfactory. To a certain extent, Avicenna had a similar formula when he said that equinitas est equinitas tantum. Now everybody knows that the whole problem of universals started from the questions raised by grounding the objective indeterminacy of such a “tantum”. It seems too easy, or a way to have one’s cake and eat it, to deny a real distinction between the Categorical and the Dispositional while agreeing that a conceptual distinction is needed, meaning by this that it must have some objective foundation, or that it is more than a distinction of reason, namely, more like what Duns Scotus would have named a formal distinction, that is “a distinction from the nature of the thing occurring between two or more really identical formalities, of which one, before the operation of the intellect, is conceivable without the others though inseparable from them even by divine power”. One way or other, some deep metaphysical issues will have to be handled here with great care.
3. Substantival or Relational Realism? Again, the “neutral” monism is in danger of committing itself to more ontology than it would surely be prepared to, at least in the following respect: In Hume’s ontology, there is a sharp distinction between the way a thing is, and how it is disposed to behave: the way it is depends on what its properties are. How it is disposed to behave depends on what the laws of nature are. The two are supposed to be independent of each other. Mumford’s general view has the great advantage of trying to account of the changes that occur in the world, from the inside: as he somewhere says, a world described entirely in categorical terms is a static world, and hence, not ours. Again, the familiar Humean point that it is a logically contingent matter what effect follows from any antecedent event, and that laws of nature are what is added to animate, so to speak, the world, has something unconvincing about it.
This is precisely such a confusion which Peirce diagnosed in the scholastics’ treatment of dispositions. As is well known, the scholastics (with the maxim operari sequitur esse) claimed that the operations or activities reflected a corresponding perfection in that thing, which could account for its ability to perform that sort of operation. It was on the basis of this principe that they were able to specify natures and natural classes. If a man performs an action that others animals cannot, such as reasoning, then the man has a power that other animals do not possess. If such a capacity is the distinguishing characteristic, it is dignified with the title “nature”. But why did Peirce finally object to the scholastic operari sequitur esse, i.e. to the substantial form as a dispositional character - aside from the question of how scientific one is in determining distinguishing characters? Because it failed to reveal the relational structure which is ultimately involved. That is, the scholastics were right, as far as they went, but their limited logic did not allow them to see that the nature, power, or disposition represented in these monadic predicates was only a truncated image of a relational law. Apparently, it was the old logic’s inability to handle abstractions properly that was mainly at fault. The scholastics did not realize that their most important abstractions were really hypostatized relations, and therefore that real abstractions indicated real relations - laws and not forms. I am not sure whether Peirce’s substitution of a relational realism to a substantival realism is necessarily the correct way of handling the problem of dispositions, but at any rate, it is true that there is, from Mumford’s part, a very unelaborated commitment to a view of what an object is in terms of a plain substance, and not much elaboration either on the “something” which justifies or constitues the truthmaker for a dispositional ascription: is it mere epistemic indeterminacy? Or is this indeterminacy linked with some irreducible, metaphysical features of, for instance, some Common Nature? Again, Mumford is obviouly committed to a trope theory view of instantiated particulars but neither does he provide an account of the process of instantiation or individuation nor does he present a justification of the reasons why he should rather favor such a view instead of another, while admitting that there are notorious difficulties, raised by Russell for example, with a tropist account.
4) The generality objection: Contingency or Necessity?
There are advantages in adopting a dispositionalist view of laws, as Mumford has clearly outlined. But the dispositionalist also faces problems: namely, how can he, without general laws, explain why generalities in behaviour are true of kinds? For example, all sugar dissolves in liquid and tastes sweet to the tongue. Is is merely a cosmic coïncidence that each sample of the kind carries the same set of capacities? Could we have rogue samples that possessed different dispositions? Here we face a very serious issue with which I am not sure I clearly understand Mumford’s position or whether he provides a satisfactory answer to it: this has to do, it seems to me, with the contingency he wants to maintain in his dispositionalist account of laws.
In the last chapter of Dispositions, Mumford clarifies the charge he had adressed in a previous article, namely that Ellis and Lierse argued that dispositional essentialism entailed “a definite answer to this debate: that dispositions were ultimate, rather than laws. This involved them making a number of controversial (and poorly justified) claims, such as the laws of nature were logically necessary instead of contingent as the Humean tradition takes them to be”. But, Mumford contends, dispositional essentialism could be true even if it were laws rather than dispositions that were in the relevant sense ultimate or basic. Which does not mean, he hastens to adds, “that the basic laws view is proved” or that he was offering a proof, even though in places he “pushed that view for dialectical purposes”. Further, “although basic dispositions as truthmakers of laws are not necessary for the claim of dispositional essentialism about certain fundamental kinds in science, as Ellis and Lierse suggested, …dispositional essentialism may be required for the credibility of the basic dispositions view because it suggests a solution to the generality problem that exists for the basic dispositions view. Hence, basic dispositions are not required by dispositional essentialism but dispositional essentialism may be required for basic dispositions” (Ibid.).
Intricate (or dialectical) as it may sound, such a formulation points to some difficulties I have in understanding Mumford’s exact position as far as the status of laws is concerned, as well as regards the explanatory role he wishes himself to confer to “basic” dispositions. In particular, is Mumford really subscribing to the contingency thesis (CT : the laws of nature are logically contingent) about laws?
In Dispositions, he explicitly says he endorses it: “Although dispositions bring natural necessity in the world there still exists the kind of logical contingency that is required. The replacement of laws with real dispositions is no threat to the view that the way nature behaves could have been otherwise but it does mean that CT will have to be revised accordingly”. Indeed, “a modified version of the CT can be given that is framed in terms of the contingency of a particular’s capacities, rather than the contingency of laws”. And he pursues: “There exist relevant conceptual necessities of dispositional essentialism, such as that described above where an electron must, conceptually, have certain dispositions if it is to be an electron. Such conceptual necessities do not threaten natural contingency in the sense that the only logical necessities are conceptual. Hence it is logically contingent that a particular entity is a particular with the capacities it actually has. That particular could have had different dispositions to the ones it actually has, even though this would entail that the particular belonged to a different kind in virtue of that fact. Such contingency does not threaten the identities for such entities across possible worlds however, for our disposition ascriptions are actual-world relative”.
Hence Mumford denies Ellis and Lierse’s move according to which dispositional essentialism requires the logical necessity of physical laws. “While it is certainly true that an electron would not be an electron if its behaviour were different from the behaviour it has in the actual world, this necessity is purely conceptual. That it is in virtue of behaviour B that a particular x is classified within a kind K does not entail that x necessarily has behaviour B”(ibid.). According to Mumford, this involves a misunderstanding of the scope of the logical necessity involved. “That a particular possesses any disposition is logically contingent even though some particulars, such as electrons, would not have been classes as such if they had a different behaviour. To deny this would be to claim that an electron’s behaviour is dictated by logic, and, presumably, physics is a trivially analytic human folly” (ibid.).
But I do not think that such a criticism is justified, at least, as far as Ellis’s dispositional essentialism is concerned, which indeed does imply some necessitarist account of dispositions, if it aims at presenting kinds of processes as discovered principles active in nature and not as invented classifications. But to a certain extent too, I do not see how Mumford can maintain, even in a reformulated way, the CT about a particular’s capacities. What he may maintain at most (and in fact, it seems to be mainly what he provides as a further account of laws in the paper given at the Grenoble Conference) are some contingent elements understood as changes or departures from the law. At all events, I doubt that one could go so far as admitting such contingency as the one Mumford alludes too: “Thus ravens are black now, meaning that it is true of the raven kind that its normal members are dispositionally black, but tomorrow, through a divine intervention, normal ravens may become dispositionally pink”. Indeed this is making fun of physics or of the laws of evolution. It seems that the contingency Mumford wants to introduce has more to do with what Peirce called “conditional necessity”, in order to account both of the both descriptive and regulative “would-be” (which was not merely a may be or a will be) character of dispositional laws and the tychistic or chance elements he deemed necessary to introduce in his both synechistic and evolutionary metaphysics.
Anyway, should that really be an advantage for the dispositionalist account of laws to try, by all means, to avoid any kind of necessity? For one thing, as we know from Kripke’s and Putnam’s works, a point also recently emphasized by F. Jackson, many necessary facts can be known to be true by a posteriori means only: certain identity statements, including identity statements concerning scientific and natural kinds, express propositions that are necessarily true, but that can be known only a posteriori. Hence, in general, as A. Bird has shown in a recent paper, the thought that laws might be necessary but knowable only a posteriori is not objectionable and should be familiar from other cases. Furthermore, it can be shown that some laws are necessary but have every appearance of contingency:
“Let us for sake of argument grant that the basic laws of nature are contingent. Let a non-fundamental law, say, a law of chemistry, assert that the substance S has some property D. We shall call this law L (S, D). This law may supervene some underlying, more fundamental (contingent) law C. So C entails (L(S,D)(i.e. necessarily, C implies L (S,D). Substances themselves exist as a result of the laws of nature. And it might be that in order for the substance S to exist, some fundamental laws must be true. In particular the existence of S might require the truth of C. Hence S exists entails C. So we have L entails C entails L(S,D). Hence the very existence of S necessitates the truth of the law L (S,D). Hence there is no world where S exists but the law L (S, D) fails to hold. Precisely this relationship can be shown to hold between the existence of salt (sodium chloride) and the law that salt dissolves in water. The underlying law in this case is Coulomb’s law which governs both the electrostatic attraction required for salt to exist and also is sufficient to encure that salt dissolves in water. Clearly the law that salt dissolves in water is a posteriori and at first sight it seems entirely contingent. But it can be shown to be necessary, even if we assume that the underlying laws are contingent”.
Whatever we decide in favour of contingent or necessary laws, it remains that one should be careful, when adopting such and such form of dispositional essentialism or realism, not to indulge in what Popper thought was the major defect of essentialism: to aim at providing an ultimate explanation of what reality consists in. While Mumford’s recourse to “ungrounded” dispositions may sometimes sound a little bit like a virtus dormitiva, I prefer to view it less as a quietist (or Wittgensteinian) invitation (something like: justification must end somewhere) than as a principle of sound, fallibilistic methodological procedure.
. « Sur la réalité des propriétés dispositionnelle », Actes du Colloque de l’université de Caen (janvier-février 2000), à paraître en 2003.
. “The Origins and Forms of Qualities”, in M. A. Stewart (ed.), Selected Philosophical Papers of Robert Boyle, Manchester, Manchester University Press, 23, 1979, 1-96.
. Cf. for ex. The Roots of Reference, La Salle, Ill., 1974, p. 11, or The Ways of Paradox, 1966, Harvard University Press, p. 71-72.
. N. Goodman, Fact, Fiction and Forecast, Indianapolis, 1955.
. G. Ryle, The Concept of Mind, London, Hutchinson, 1949.
. Ian .J.Thompson, “Real Dispositions in the Physical World”, British Journal for the Philosophy of Science, 1988, 39, 67-79, p. 76-77.
. Rom Harré, “Powers”, British Journal for the Philosophy of Science, 2, 1970, 55-101; R. Harré & E.H. Madden, “Natural Powers and Powerful Natures”, Philosophy 48, 1973, 209-230 ; R. Harré & E.H. Madden Causal Powers: A Theory of Natural Necessity, Oxford, Blackwell, 1975.
. Nature’s Capacitie and their Measurement, Oxford, Clarendon Press, 1989: “It is not the laws that are fundamental, but rather the capacities”(p. 181); also see The Dappled World, Cambridge, Cambridge University Press, 1999.
. A World of Propensities, Bristol, Thoemes Press, 1990.
. D.H. Mellor, especially “In Defense of Dispositions”, Philosophical Review, 83, 1974, 157-181; “Counting Corners Correctly”, Analysis, 42, 1974, 96-97 and “The Semantics and Ontology of Dispositions”, Mind, vol. 109, 436, oct. 2000, 757-779.
. For Blackburn, science finds dispositions “all the way down”, “Filling in Space”, Analysis, 50, 1990, 62-5.
. Cf. S. Blackburn, ibid.
 . I have tried to spell out some arguments in favor of such a position in « Sur la réalité des propriétés dispositionnelles », art.cit.
. B. D. Ellis & C. E. Lierse, “Dispositional Essentialism”, Australasian Journal of Philosophy 72, 1994, 27-45 ; “Natural Kinds and Natural Kind Reasoning”, in Natural Kinds, Laws of Nature and Scientific methodology, P. Riggs (ed.), Kluwer Academic Publishers, Dordrecht, 1996, 11-28 ; “Causal Powers and the Laws of Nature”, in Causation and Laws of Nature, H. Sankey (ed.), Kluwer Academic Publishers, Dordrecht, 1999, 21-42 ; “Bigelow’s Worries about Scientific Essentialism”, ibid., 77-97 ; “Response to D. Armstrong”, ibid., 49-55 ; Scientific Essentialism, Cambridge University Press, 2001 ; and for a good summary of his position, see “The New Essentialism and the Scientific Image of Mankind” (NESIM), http://www.rescogitans.it/ita/scenari/tilgher/Ellis.htm.
. Cf. NESIM, 3 “Scientific essentialism”.
 . NESIM, 3.
. Ibid., and Scientific Essentialism, op.cit., p.3.
. NESIM, 3 and Scientific Essentialism, op.cit., p. 6.
. NESIM, 3. Cf. Scientific Essentialism, op.cit., p. 106-144. This is what D. Armstrong objects to. See his “Reply to Ellis”, in Causation and Laws of Nature, op.cit., 43-48. He argues that such intrinsic causal powers are Meinongian properties, and thus objectionable. In principle, he says, there could be causal powers which happen never to be exercised. If such properties have no categorical bases, as Ellis allows is possible, then such powers can be defined only by relationships between non-existent objects, i.e. between the kind of circumstances which would trigger them and the kind of display which would then result. For Ellis’s answer see op.cit., p. 133-135.
. NESIM, 3. Ellis claims that it is this second tenet of scientific essentialism which sets it apart most strongly from other theories of the nature of reality.
. NESIM, 4.
 . Scientific Essentialism, op.cit., p. 2.
. NESIM, 4.
. Op.cit., p. 107 ff.
. See Scientific Essentia lism, op.cit., p. 4, p. 7, and p. 44 ff, p. 211 ff., p. 229 ff., p. 261 ff.
. Op.cit.,part four, chaps. 6 and 7, p. 203 ff.
. “The most elementary kinds of things all have fixed causal powers, i.e. their dispositional properties are all fixed by their essential natures. A copper atom, for example, has the same dispositional properties wherever or whenever it might occur. The same is true of a proton or an electron. They are things which belong to what might be termed “fixed natural kinds”.Their distinguishing feature is that you cannot change any of their dispositional properties. They do what things of these kinds always do, and you cannot teach them any new tricks. There can be no question of a copper atom, for example, being disposed to behave in one way at one time, but in a different way at another time. Nothing with such variable powers could possibly be a copper atom”. NESIM, 5.
. B. Ellis & C. Lierse, art. cit., p. 40.
. I have shown in « sur la réalité des propriétés dispositionnelles » (art.cit.), the difficulties raised by a « functionalist » account of dispositions. On the problems linked with « functions », see also J. Searle, The Construction of Social Reality, 1995, New Yok, éditions Free Press, p. 29 ff.
. “Ellis and Lierse on Dispositional Essentialism”, Australasian Journal of Philosophy, 73, 1995, 606-612.
. Clarendon Press, Oxford, 1998, p. 234 ff.
. Op.cit., p. 14.
. Op.cit., p. 122. This means, in particular, that mere “Cambridge changes” are not allowed. S. Shoemaker also agrees on that criterion; see his “Causality and Properties”, Time and Cause, edited by P. van Inwagen (Dordrecht : D. Reidel, 1980), 109-35, repr. in Properties, ed. by D. H. Mellor & Alex Oliver, Oxford: Oxford Readings in Philosophy, 1997, 228-254, p. 232. cf. Evan Fales in Causation and Universals, p. xiii: “A physical universal exists if and only if it is a member of the causal ‘web’ ; if it is then it exists whether or not it is ever instantiated” quoted by Mumford, op.cit., p. 123. Let us note that some philosophers do no accept the idea that the causal criterion should be a criterion for the existence of a property. For ex., Alex Oliver, “The Metaphysics of Properties”, Mind, vol. 105, 417, jan. 1996, 1-80, p. 8..
. Art.cit., p. 27. The philosophers they cite are R. Harré and E.H. Madden, as well as Evan Fales, who “has argued that the essential properties of the most fundamental natural kinds are their monadic properties, and, in so far as these properties are dispositional, things of these kinds must behave as these properties prescriube” (Evan Fales, “Essentialism and the Elementary Constituents of Matter”, Midwest Studies in Philosophy, 11, 1986, 391-402, Causation and Universals, London, Routledge, 1990). Nevertheless, Ellis and Lierse admit that “in the case of the fundamental particles, the dispositional properties may indeed be all that we have” (art.cit., p. 29). Mumford agrees with this. Not only does he admit the possibility of “ungrounded dispositions”, but his functional analysis makes him give importance to such functionalist systems as “thermostats” or thermometers whose essence is clearly entirely dispositional (op.cit., p 8), i.e. that “the exact mechanisms that equip a thermostat with the dispositions it has are, in a significant way, irrelevant to the fact that it is a thermostat.. Roughly, for something to be a thermostat, it must be sensitive to changes in temperature and be able to trigger a switch if a pre-calibrated temperature threshold is crossed”(ibid.).
. Dispositions, op.cit., p. 63. See chaps 3 and 4 for more details: “What I suggest is the rejection of a solely conditional analysis of dispositions and that we treat them as real instantiations of properties which afford possibilities rather than just being shorthand ways of talking about certain combinations of events”.
. “Counting Corners Correctly”, art.cit., p. 97. Ellis & Lierse note that Mellor’s dispositional foundationalism, which purports to tbe Humean, faces difficulties: “By embracing the Contingency Thesis, Mellor, at the very least, has to subscribe to the view that the laws in this world are only contingently related to the entities that exist in it. Thus, the behaviour of an entity must be logically distinct from the kind of thing it is. Now, if Mellor wants to 1) deny the existence of categorical properties, 2) avoid embracing a behaviourist theory of dispositions, and 3) have an ontology of occurrent properties, then his only option is to identify a disposition with some occurrent property or properties which are not dispositional. But what could these be? Could they be, perhaps, those structural or other properties which must exist if the disposition is to exist?” (art. cit., p. 35).
. He is very careful to distinguish the two levels. See for ex. p. 145: “The thesis of property dualism tries to take this distinction (ie. C-D) further into ontology. Property Monism, on the other hand, is the claim that the conceptual distinction is the only distinction because it denies that there is an ontological division in reality which the conceptual division maps”. “There are not distinct categorical and dispositional types of properties but there are distinct categorical and dispositional ways of talking about instantiated properties”.
. “In particular, if ‘categorical’ means ‘unconditional’, dispositions are, in a very obvious way, categorical : when I say that a particular sugar-cube is soluble, I am in no way making an ascription conditionally for I am saying that it is actually soluble now, not that it could be soluble if some other conditions obtained”(p. 64).
. Dispositions, op.cit., p. 77.
. Dispositions, op.cit., p. 145. In particular this means that “the identity conditions for properties are separated from the identity conditions for predicates”(p. 146). At the same time, it implies also, as Armstrong puts it, “the emancipation of the theory of universals from the theory of semantics”, A Theory of Universals, Cambridge, Cambridge University Press, 1978, p. 6. For Mumford this position has the following consequence: “We can have property monism even if identification between universals cannot be made. The only problem becomes, whether there is some plausible notion of a property instance that can warrant our consent”(p. 160).
. Op.cit., p. 146.
. Op.cit., p. 148.
 . Ellis & Lierse, art.cit., p. 31.
 . Dispositions, op.cit., p. 229.
. Ibid., p. 231.
. Ibid., p. 233.
. This indeterminacy in a deterministic world is due to the linguistic vagueness. Hence, “To define fragility, for example, we cannot do much better than say that a fragile object is likely to break if dropped, or otherwise handled roughly. Any more precise definition might capture some more specific concept of fragility. But it would not be the broad but vague concept with which we are familiar”. On the contrary, in an indeterministic world such as ours, “the dispositions are causally interminate, not because of vagueness, but because of the indeterminacy underlying phsycial processes. For example, the probability that a radium atom existing at t will have decayed by t + ∂ is, for any given frame of reference, a precisely specifiable function of ∂, and this probability is independent of the circumstances in which the radium atom exists. Hence, we cannot, even in principle, eliminate this causally indeterminate disposition in favour of any more precisely defined dispositions which are causally determinate” (Ellis & Lierse, art.cit., p. 42).
. “Where we have a causal disposition, there is typically a certain pattern of cause-and-effect or stimulus-and-response which anything having the disposition would normally display if it were appropriately caused or stimulated to do so” (Ellis & Lierse, art.cit., p. 40).
. “A Stochastic disposition is a propensity of some kind, in which the antecedent condition is not strictly the cause of its manifestation, but only a necessary condition for it. For example, the disposition of a radium atom to decay in a certain way is a stochastic disposition. If this species of radioactive decay is to occur, it is a necessary condition that radium atomes should exist. But events of radioactive decay are not caused by the existence if such atoms. Not, as far as they know, are they caused by anything else. There is just a certain objective probability p that within any given-time interval ∂ such an event will occur’ (ibid., p.40).
. Dispositions, op.cit., p. 217.
. Op.cit., p. 221.
. Counterfactuals, Blackwell, 1973 and “Humean Supervenience Debugged”, Mind, 1994.
. F. Dretske, “Laws of Nature”, Philosophy of Science, 1977, 248-268.
. M. Tooley, “The Nature of Laws”, Canadian Journal of Philosophy, 1977, 667-698; Causation: a Realist Approach, Oxford, Clarendon Press, 1987.
. What is a Law of Nature? Cambridge, Cambridge University Press, 1983.
. See A. Bird, “The Dispositionalist Conception of Laws”, Foundations of Science (forthcoming) 2003. The best of these is the systematic regularity theory of Lewis (following from Ramsey), Counterfactuals, Cambridge, Mass., Harvard University Press, 1973, p. 72-77: according to this view, a generalisation states a law only if it is deducible from that axiomatic systematisation of the facts that optimally combines strength and simplicity. While this reduces the pressure of the objection from accidental regularities, it does not, as Bird notes, remove it altogether. “For we could imagine a system of laws that was itself rather complicated and weak but which generated an accidental regularity, whose addition to the axiomatic sytem might in fact add considerably to its strength without detracting much from its overall simplicity”.
 . Dispositions, op.cit, p. 122 ff.
. When the relation holds between two universals it entails the corresponding generalisation but the reverse entailment does not.
. S. Mumford, « L’état des lois», paper from the Conference which took place at the University of Grenoble (december 2000), in Objets, propriétés, états de choses : le renouveau de la métaphysique australiene, Paris, Vrin.
. C. B. Martin,”Dispositions and Conditionals”, The Philosophical Quarterly, 44, 1994, 1-8. Note that C.S. Peirce makes a similar remark: “what the chemist is interested in is not the particular sample, but the molecular structure”, The Collected Papers of C.S. Peirce, Cambridge, Mass., Harvard University Press, (8 vols. 1939-1958), vol. 4, § 530.
 . This is more than a counterfactual difference, Dispositions, op.cit., p. 231.
. Dispositions, op.cit., p. 210.
 . Ibid., p. 213.
. Collected Papers, op.cit., vol.1. §27n1.
. Mellor, 2000, art.cit., 757-779.
. Mellor, Matters of Metaphysics, Cambridge, Cambridge University Press, 1991, p. 171. See also B. Ellis, op.cit., p. 18, n.1.
. 1997, A World of States of Affairs, Cambridge, Cambridge University Press, chap. 6.6.
. Ryle, 1949, chap. 5.
. S. Mumford, op.cit., p. 215.
. M. J. Grajewski, The Formal Distinction of Duns Scotus, Washington, 1944, p. 93.
. Cf. Ellis & Lierse, art.cit., p. 28.
. Op.cit., p. 214.
. Collected Papers, vol. 6 § 361.
. Collected Papers, vol. 3 § 642.
. He rejects’s Prior’s contention that some identification of properties as universals is needed. Mumford claims that he can have property monism even if identification between universals cannot be made. The only problem becomes whether there is some plausible notion of a property instance that can warrant our consent. One candidate notion is that of trope, being an “abstract particular”(cf. K. Campbell, Abstract Particulars, Oxford 1990, or J. Bacon, Universals and Property Instances, Oxford, 1996), such as the redness of a particular apple or the squareness of a particuler window. According to the ontology of tropes, squareness and redness in general do not exist, but only as samples of particular rednesses and squarenesses of things. But, as Mumford himself admits, the problem with such an account is notorious, and was noted by B. Russell: the trope theorist cannot explain how a number of tropes resemble each other. How is it that ten red things are all red, for instance? Mumford has this formulation : “Unless we accept some notion of properties being instantiated in particulars, then it seems difficult to sustain the evident link between a thing’s properties and the causal transactions into which it enters. It is difficult, in short, to see how, unless we allow that there are particular property instances possessed wholly by objects and substances, a thing’s properties can have causal effects. What causes a square peg to fit a square hole? It is not a timeless universal that exists nowhere, rather it is something about this hole and this peg, regardless of what else exhibits a similar quality elsewhere”. (op.cit., p. 161). Indeed, but it is precisely on the “something about” that we expect some explanation
. Cf. op.cit., p. 221 ff.
 . Op.cit., p. 235-236.
. Op.cit., p. 236-237.
. Collected Papers, vol. 2 § 664. This is a point recently emphasized by A. Bird, “Necessarily Salt Dissolves in Water”, Analysis 61, 2001, 267-275, and “On whether some laws are necessary’, Analysis 62 (2002), 257-274.
. Cf. C. Tiercelin, « C.S. Peirce et le projet d’une métaphysique scientifique évolutionnaire », Publications de la Sorbonne, Philosophie 5, nov. 2000, 453-463.
. From Metaphysics to Ethics: a Defense of Conceptual Analysis, Oxford, Clarendon Press, 1998. I have analysed and commented such views in C. Tiercelin, « La métaphysique et l’analyse conceptuelle », Revue de Métaphysique et de Morale, oct-déc. 2002, 559-584.
. “The Dispositionalist Conception of Laws”, forthcoming (2003). Available in PDF on A. Bird’s web page.
. Cf A. Bird, ibid., p. 8, § 7.1; see also A. Bird, “On whether some laws are necessary”, Analysis 62, july 2002, 257-270.