Are propensities (powers, etc.) the right kind of thing to be substance? Let us examine the proposal from the previous post.
One might object that propensities do not appear to have enough being, as they appear instead always to point to an incipient state of becoming. Are they, as Armstrong (1997) claims, always packing but never arriving? Would objects made of such substance as proposed here actually exist, or only potentially exist, or (perhaps) exist potentially? Bird (2007) responds to this by pointing out that this objection assumes that powers or dispositions are not fully actual. Rather, he says, we should insist that powers are actual full-blooded features of objects and that what is merely potential are their manifestations. I would respond slightly differently: powers are the actual full-blooded substance of objects and are not merely the ‘features’ or ‘properties’ of objects.
Perhaps we wonder whether objects made of such substance are really ‘full-blooded’. Do such substantial objects persist as objects should? How do they have being? Can they be individuated properly? Are they simple units, or can they be divided? Could elementary particles be of such substances? Could we be such objects and still feel our own reality? Let us discuss some of these issues.
Do these new kinds of substance persist? There is certainly no need for them to persist forever, but can they persist through accidental changes while maintaining their essential nature? To answer the question about persistence, we note that dispositions are possessed even when they are not being manifested. A vase is still fragile when it is not breaking. The fragility persists for a finite duration: at least from one contact event until the next. What I am asserting is that the corresponding substance of the glass persists for at least exactly that same duration. In that duration, it may change its position, orientation or illumination. These are the variable accidental properties that vary while the underlying substance (fragility and the other dispositions) remain the same. Whether the underlying substance persists forever is the same question as whether the fragility (etc.) persists forever. That can be answered by looking at the future adventures of the vase in the world. If the fragile glass ceases to exist, then the substance ends, perhaps by being changed into another kind of substance. That substantial objects might persist only for a finite time does not render them any less enduring or persistent objects during that time.
How do these substances have ‘being’? The recent dispositional essentialists have taken all properties as ‘powers, and nothing but powers’, so we wonder if we can take all objects similarly. The claim was thought by Bird (2009) to include all properties, including all those previously thought categorical such as position, shape and structure. I do not hold such a strong view. Particular objects have both dispositional and categorical properties, once we understand how this is to be conceived. The dispositional properties are instantiated by the underlying dispositional substance, whereas the categorical properties are instantiated by the form or structure of that substance which makes up this specific object. In this way we have what Martin (1993) calls a ‘Janus-faced’ or ‘dual-aspect’ view, but of objects rather than of properties. We are thereby constructing a notion of substance wherein substantial objects legitimately have both dispositional and categorical aspects. We do not follow Jacobs (2011) in having ‘powerful qualities’ that have both dispositional and qualitative sides. Rather it is the substantial objects that have both. Now, some but not all properties are dispositional. We do not deny the semantic distinction between dispositional and categorical properties but rather reinforce it. Neither do we have a ‘neutral monism’ whereby the dispositional and categorical are ‘modes of presentation’, following Mumford (1998), of the same instantiated properties.
Many philosophers since Prior et al. (1982), and recently, Rives (2005) have argued that dispositions are ‘causally impotent’ following the argument that “if dispositions are distinct from their categorical bases, and their bases are efficacious, then the dispositions themselves are impotent.” Rives explicitly assumes that “the causal efficacy of categorical properties is not in question”. I disagree. I think categorical properties such as size, shape, structure are by themselves never causally efficacious. We saw that above. Such properties are only efficacious when they are shapes or structures of some substantial object, and this requires the participation of dispositional properties. A ‘base’ can never be a structure per se and hence never purely categorical.
A summary of the new position is to say that specific objects are unions of form and power, of qualitative and dispositional aspects. Objects are structures of propensity, namely forms of substance, in a good Aristotelian manner. Forms may be examined in great detail by form-al sciences such as mathematics and logic, but no natural changes can be generated by formal constructions. For example, contemporary attempts in physics to construct ‘it from bit’ (to derive existence from form) can only produce a static (timeless) universe without changes or causes of change. I would instead say that forms are the means by which dispositional powers operate, since the power-substances can only operate if they are arranged in some form or structure that allows for interaction and movement. Conversely, forms can only have an impact on the world if they are the forms of some propensity, as thereby a physical object in the world is in existence and has powers to influence others. This is why I said that objects in the world are required to be unions of form and power: they require powers to be in some form and require forms to be of some power. The resulting union has an existence that goes beyond either ingredient by itself. In a natural object, the power and form are actually inseparable and only abstractly distinguishable. We can (and should) intellectually distinguish them—as recent philosophers have emphasized—but that does that mean that they can ever exist apart.
Can these substantial objects be individuated? Can we identify individual objects made of such substance? It certainly does not seem that we can divide powers or propensities themselves into parcels, with some for each individual object in the world. I can only see individuation proceeding via the specific forms or trope that the substance-stuff has in specific objects. That is, identifying individual objects, as forms of the underlying substance-stuff, can only proceed by identifying those particular forms used in each individual object. We may say that even the individual and specific existence of an object depends on the specific forms that inform the essential underlying powers/propensities of the substance.
Some scientists may be suspicious of the idea that there is a fundamental level where objects are composed of dispositions directly and do not have parts in substructures. Would that not be the end of science? No, because science’s task is to first determine which is the fundamental level. Secondly, scientists try to exactly characterize and understand all those dispositions, both common and uncommon, in order to predict their exact operation. Any such claims are subject to empirical verification or revision.
Finally, we must consider the logical plausibility of this proposed identity. Grammatically, nouns in sentences are the agents of actions and refer to the bearer of causal influences. The object of an action must cooperate in the operation of those influences. This is entirely consistent with the present claim that subjects and objects are themselves forms of propensity. It is the nature of powers and propensities to be causal influences, so any thing constructed from them will be the bearer of causal influences. We must agree, therefore, to a grammatical move of powers from being adjectives within predicates to being the substance of subjects and objects. Then we must envisage as nouns the forms of such powers and propensities. This seems to me to be quite feasible.
 I would doubt that vases are eternal. I not believe that electrons or nuclei are necessarily eternal either.
 Psillos (2006) also makes this mistake, when he argues that “fundamental properties [..] flow from some fundamental symmetries," for symmetries, as purely mathematical structures, can never physically ‘flow’, and can never produce physical objects. Rather, in our Aristotelian framework, they describe the properties of objects and, here, relations between those properties. It cannot be that “elementary particles are the irreducible representations (irreps) of a group," again because groups (or even their representations) have no causal powers.
 Neither can exist by itself. No dispositions can exist except in a form, and no forms can exist except as forms of dispositions.
 Ellis (2010) has recently written in support of this view of forms as being both categorical and necessary for the operation of powers.
 A hammer and a vase must have powers to interact with each other if fragility is to be manifested this way.
Armstrong, D. M. 1997. A world of states of affairs. Cambridge; New York: Cambridge University Press.
Bird, Alexander. 2007. Nature’s metaphysics: Laws and properties. Oxford; New York: Clarendon Press; Oxford University Press.
Bird, Alexander. 2009. Structural properties revisited. Oxford; New York: Oxford University Press: Clarendon Press;.
Ellis, Brian D. 2010. Causal powers and categorical properties. New York: Routledge.
Jacobs, J.D. 2011. Powerful qualities, not pure powers. Monist, 94(1), 81–102.
Martin, C. 1993. The need for ontology - some choices. Philosophy, 68(266), 505–522.
Mumford, Stephen. 1998. Dispositions. Oxford; New York: Oxford University Press.
Prior, E.W., Pargetter, R., and Jackson, F. 1982. 3 theses about dispositions. American Philosophical Quarterly, 19(3), 251–257.
Psillos, Stathis. 2006. What do powers do when they are not manifested? Philosophy and Phenomenological Research, 72(1), 137–156
Rives, B. 2005. Why dispositions are (still) distinct from their bases and causally impotent. American Philosophical Quarterly, 42(1), 19–31.