E. J. Lowe

(1950 - 2014)

When, for example, we say of something that it ‘is an object’, or ‘is an event’, or ‘is a property’, we are engaging in categorial predication: we are assigning something to a certain ontological category. Ontological categorization is clearly a type of classification, but it differs radically from the types of classification that are involved in the taxonomic practices of empirical sciences, as when a physicist says of a certain particle that it ‘is an electron’, or when a zoologist says of a certain animal that it ‘is a mammal’, or when a meteorologist says of a certain weather‐phenomenon that it ‘is a hurricane’. Classifications of the latter types presuppose that the items being classified have already been assigned to appropriate ontological categories, such as the categories of object, species, or event. What do categorial predications mean? How are their truth‐conditions to be determined, and how can those truth‐conditions be known to be satisfied? Do they have truthmakers? Questions like these are amongst those addressed in the present paper

John Heil’s new book is remarkable in many ways. In a concise, lucid and accessible manner, it develops a complete system of ontology with many strikingly original features and then applies that ontology to fundamental issues in the philosophy of mind, with illuminating results. Although Heil acknowledges his intellectual debts to C. B. Martin, he is unduly modest about his own contribution to the development and application of this novel metaphysical system. A full examination of the position that Heil defends would require a book in itself, so I shall limit myself to discussing some of its central themes and to explaining a few doubts that I have concerning some aspects of it.

A self or person does not appear to be identifiable with his or her organic body, nor with any part of it, such as the brain; and yet selves seem to be agents, capable of bringing about physical events as causal consequences of certain of their conscious mental states. How is this possible in a universe in which, it appears, every physical event has a sufficient cause which is wholly physical? The answer is that this is possible if a certain kind of naturalistic dualism is true, according to which the conscious mental states of selves, although not identifiable with physical states of their brains, are emergent effects of prior physical causes. Moreover, mental causation on this model promises to explain certain aspects of physical behaviour which may appear arbitrary and coincidental from a purely physical point of view

Recently, Terry Horgan and Matjaž Potrč have defended the thesis of ‘existence monism’, according to which the whole cosmos is the only concrete object. Their arguments appeal largely to considerations concerning vagueness. Crucially, they claim that ontological vagueness is impossible, and one key assumption in their defence of this claim is that vagueness always involves ‘sorites-susceptibility’. I aim to challenge both the claim and this assumption. As a consequence, I seek to undermine their defence of existence monism and support a common-sense pluralist ontology of ‘ordinary objects’ as being fully consistent with a thoroughgoing metaphysical realism.

Three different concepts of matter are identified: matter as what a thing is immediately made of, matter as stuff of a certain kind, and matter in the (dubious) sense of material ‘substratum’. The doctrine of hylomorphism, which regards every individual concrete thing as being ‘combination’ of matter and form, is challenged. Instead it is urged that we do well to identify an individual concrete thing with its own particular ‘substantial form’. The notions of form and matter, far from being correlative, are relatively independent. There is nothing absurd in the notion of form without matter. Matter provides neither a principle of individuation nor a criterion of identity for individual concrete things: their form alone provides both. Finally, a substance ontology which admits also the existence of particular qualities, or tropes, is to be preferred both to a substance ontology which denies the existence of tropes and to a pure trope ontology.

Objects which philosophers have traditionally categorized as abstract are standardly referred to by complex noun phrases of certain canonical forms, such as ‘the set of Fs’, ‘the number of Fs’, ‘the proposition that P’, and ‘the property of being F’. It is no accident that such noun phrases are well-suited to appear in ‘Fregean’ identity-criteria, or ‘abstraction’ principles, for which Frege’s criterion of identity for cardinal numbers provides the paradigm. Notoriously, such principlesare apt to create paradoxes, and the most intuitively plausible ‘Fregean’ identity-criterion for properties is afflicted by this problem. In this case, it may be possible to overcome the difficulty by modifying the criterion in a way which requires an independent account of the existence-conditions of properties, but it appears that such a strategy demands acceptance of the doctrine of immanent realism—the view that a property exists only if it is exemplified by some object.

I propose a fourfold categorisation of entities according to whether or not they possess determinate identity-conditions and whether or not they are determinately countable. Some entities – which I call ‘individual objects’ – have both determinate identity and determinate countability: for example, persons and animals. In the case of entities of a kind K belonging to this category, we are in principle always entitled to expect there to be determinate answers to such questions as ‘Is x the same K as y?’ and ’How many Ks are there satisfying condition C?’, even if we may sometimes be unable in practice to discover what these answers are. But other entities apparently lack either determinate identity, or determinate countability, or both. In these terms I try to explain certain important ontological differences between familiar macroscopic objects and various rather more esoteric entities, such as the ‘particles’ of quantum physics, quantities of material stuff, and tropes or property instances.