In recent years, a growing number of philosophers have appealed to various individuative entities (e.g. tropes or Leibnizian essences) to solve a specific philosophical problem. Moreover, the problem of individuation is an essential aspect of the problem of universals. For these reasons, it is important to be clear on issues and options in the problem of individuation. In this chapter, the problem of individuation will be clarified, two solutions will be analysed and bare particulars will be defended as the best answer.

The problem of individuation

The notion of a problem of individuation has come to be used for a wide variety of different, and not altogether related matters in philosophy ranging from linguistic, conceptual or epistemological issues of singling something out at or through time to more distinctively metaphysical concerns. To clarify the specific sense used here, recall Socrates and Plato, two red, round spots that share all their pure properties in common. The problem of individuation is the problem of offering an ontological assay of the situation so as to specify what it is that makes the two spots two particular, individual entities instead of one. So understood, this problem of individuation requires an answer to two different but intimately related questions:

1. • How are we to characterize individuality ontologically? To what ontological category or logical type does individuality belong?

2. • What sort of distinction is there between the individuality and nature of an individual like Socrates or Plato: a real distinction, a modal distinction, a distinction of reason, or some other distinction?

This book is a study in analytic ontology with a focus on issues and options at the core of the problem of universals. The problem of universals is actually a cluster of related issues central to debates among extreme nominalists, moderate nominalists and advocates of various forms of realism about the ontological status of properties. The book is intended to be an introduction to the topic and I have aimed the level of exposition at upper level undergraduates, graduate students and professional philosophers, and I believe the book should be of value to all three groups. Given the intended audience, the book is an introduction, not in the sense of being aimed at beginning students in philosophy, but in the sense of seeking to focus on the most important issues central to the subject matter. Because of this focus and space limitations, I have of necessity refrained from addressing certain topics in the study of universals that have been prominent in the past ten years, specifically: the relationship between higher and lower order universals; the relationship between universals and causation, laws of nature and scientific explanation; the use of moderate (especially trope) nominalism to do work in various areas of philosophy. As interesting as these topics may be, those who study them bring to their reflections positions on the more fundamental topics about universals. And, often, philosophers who discuss these current issues seem unfamiliar with or inadequately appraised of important distinctions and arguments at the core of those more fundamental topics.

Along with the metaphysics of substance, the problem of universals is the paradigm case of a perennial issue in the history of philosophy. The problem of universals is actually a set of related issues involving the ontological status of properties. Prima facie, it would seem that properties exist. Indeed, one of the most obvious facts about the world is that it consists of individual things that have properties and that stand in relations to other things. It would also seem that several objects can have the same property; for example, several things can possess the same shade of red. But both the existence and nature of properties have long been a matter of dispute and the problem of universals is the name for the issues central to this debate.

Those who accept the existence of universals have appealed to a number of phenomena to make their case (e.g. the meaningfulness of language, the lawlike nature of causation, the inter-subjectivity of thinking, our ability to classify and recognize new entities, gradation and the need for perfect standards or ideal paradigms). However, historically, the problem of universals has been mainly about the “One and Many” (a.k.a. “One over Many”, “One in Many”), which involves giving an account of the unity of natural classes. To illustrate, consider the following words: RED, RED, BLUE. How many words are in the sequence? Two answers seem possible: either two or three words.

In Chapter 2, reasons were given for thinking that extreme nominalism is an inadequate view of properties. However, even if this is correct, it would be premature to conclude that properties are universals because moderate nominalism – the view that properties exist and are abstract particulars – is a live option. On this view, Socrates and Plato each has its own redness, red1 and red2, respectively, and red1 and red2 are individualized properties. In this century, the three most prominent moderate nominalists have been G. F. Stout, D. C. Williams and Keith Campbell. Rather than analysing moderate nominalist treatments of predication, resemblance and abstract reference in topical fashion, it will be more useful to approach moderate nominalism by stating and evaluating the positions of its major advocates. Stout's moderate nominalism will be mentioned only briefly because although it is an important and distinctive version of moderate nominalism it has not been particularly influential, at least not in its idiosyncratic features. Williams's moderate nominalism has been appropriated, clarified and expanded by Keith Campbell, who is, arguably, the most articulate advocate of moderate nominalism. Thus, Williams's views will not be examined directly and will be mentioned only when it is helpful in clarifying the exposition of Campbell. In what follows, Stout's moderate nominalist will be investigated, followed by a detailed treatment of Campbell's position. Along the way, issues in predication, resemblance and abstract reference will be central to the dialogue.

In Chapters 2 and 3, reasons were given for preferring realism over both schools of nominalism. In Chapters 4 and 5, different versions of realism were analysed, and traditional realism was clarified and defended. Still, there are objections to realism – traditional or otherwise – yet to be considered. Moreover, intriguing topics surface in developing a mature realist position on properties and their instances. It is impossible to cover all the relevant topics in one short chapter or, indeed, in one book. So the discussion to follow will be limited to subjects that regularly arise in the literature and that are interesting in their own right. The first section contains an examination of three arguments against realism and the second presents two issues that are part of a developed realist ontology, viz. the existence of uninstantiated universals and the relationship between properties and existence.

Three objections to realism

Three objections to realism surface frequently: realist vicious regresses, problems with identity conditions for properties and difficulties reconciling naturalism with knowledge of abstract objects.

The realist vicious infinite regresses

Three regress arguments have been raised against realists: the third man argument; an argument focusing on an ascending hierarchy of exemplificational properties; and an exemplification relational regress argument. The third man argument was discussed in Chapter 1 and will not be examined here.

The hierarchy of exemplificational properties argument goes like this. According to realists, when some object a has a property being F, then this is to be explained as a exemplifying F-ness.

In Chapters 2 and 3, reasons were given for rejecting extreme and moderate nominalist analyses of properties and property-instances. This provided justification for the claim that a realist analysis is the correct one. However, in Chapter 4 it became evident that there are different positions that claim to be realist ones. And two of those positions – Wolterstorff's and Armstrong's – were found to have serious problems sufficient to justify the search for a more adequate solution to the problem of universals. In this chapter, the focus will be two-fold. First, an analysis of the traditional realist construal of properties and property-instances will be offered and evaluated. In the process, it will become clear that an essential component of the traditional view is an assay of property-instances as complex entities. However, some philosophers opine that any ontology with property-instances over and above properties and concrete particulars is a moderate nominalist ontology. This claim is sometimes illustrated by proffering a moderate nominalist interpretation of Edmund Husserl's ontology. The second focus of the chapter is an analysis and rebuttal of the supposed connection between nominalism and property-instances in general, and moderate nominalism and Husserl in particular.

The traditional realist view of predication

Traditional realism, predication, and property-instances

To elaborate on a traditional realist understanding of properties and property-instances, recall our round, red spot, Socrates. According to traditional realism, a universal is a multiply exemplifiable entity that is a numerically identical constituent in each of its instances. Thus, instances are not simples for a traditional realist; they are complex entities.