Wikipedia

# Property (philosophy)

In logic, mathematics, and philosophy, a property is a characteristic of an object; a red object is said to have the property of redness. The property may be considered a form of object in its own right, able to possess other properties. A property, however, differs from individual objects in that it may be instantiated, and often in more than one thing. It differs from the logical/mathematical concept of class by not having any concept of extensionality, and from the philosophical concept of class in that a property is considered to be distinct from the objects which possess it. Understanding how different individual entities (or particulars) can in some sense have some of the same properties is the basis of the problem of universals.

## Metaphysical Debates about the Nature of Properties

In modern analytic philosophy there are several debates about the fundamental nature of properties. These center around questions such as: Are properties real? Are they categorical or dispositional? Are properties physical or mental?

### Realism vs. Anti-Realism[1]

A realist about properties asserts that properties have genuine existence. One way to spell this out is in terms of exact, repeatable, instantiations known as universals. The other realist position asserts that properties are particulars (tropes), which are unique instantiations in individual objects that merely resemble one another to various degrees.

The anti-realist position, often referred to as nominalism claims that properties are names we attach to particulars. The properties themselves have no existence.

### Categoricalism vs. Dispositionalism[2]

According to the categoricalist, dispositions reduce to causal bases. The fragility of a wine glass, for example, is not a property that exists in the glass. Rather it can be explained by the categorical property of the glass's micro-structural composition.

Dispositionalism, in turn, asserts that a property is nothing more than a set of causal powers.[3] Fragility, according to this view, identifies a real property of the glass (e.g. to shatter when dropped on a sufficiently hard surface).

Several intermediary positions exist.[4] The Identity view that states that properties are both categorical(qualitative) and dispositional, they are just two ways of viewing the same property. One hybrid view claims that some properties are categorical and some are dispositional. A second hybrid view claims that properties have both a categorical(qualitative) and dispositional part, but that these are distinct ontological parts.

### Physicalism, Idealism, and Property dualism

Property dualism: the exemplification of two kinds of property by one kind of substance

Property dualism describes a category of positions in the philosophy of mind which hold that, although the world is constituted of just one kind of substance—the physical kind—there exist two distinct kinds of properties: physical properties and mental properties. In other words, it is the view that non-physical, mental properties (such as beliefs, desires and emotions) inhere in some physical substances (namely brains).

This stands in contrast to physicalism and idealism. Physicalism claims that all properties, include mental properties, ultimately reduce to, or supervene on, physical properties.[5] Metaphysical Idealism, by contrast, claims that "something mental (the mind, spirit, reason, will) is the ultimate foundation of all reality, or even exhaustive of reality."[6]

## Essential and accidental properties

In classical Aristotelian terminology, a property (Greek: idion, Latin: proprium) is one of the predicables. It is a non-essential quality of a species (like an accident), but a quality which is nevertheless characteristically present in members of that species. For example, "ability to laugh" may be considered a special characteristic of human beings. However, "laughter" is not an essential quality of the species human, whose Aristotelian definition of "rational animal" does not require laughter. Therefore, in the classical framework, properties are characteristic qualities that are not truly required for the continued existence of an entity but are, nevertheless, possessed by the entity.

## Determinate and determinable properties

A property may be classified as either determinate or determinable. A determinable property is one that can get more specific. For example, color is a determinable property because it can be restricted to redness, blueness, etc.[7] A determinant property is one that cannot become more specific. This distinction may be useful in dealing with issues of identity.[8]

## Lovely and suspect qualities

Daniel Dennett distinguishes between lovely properties (such as loveliness itself), which, although they require an observer to be recognised, exist latently in perceivable objects; and suspect properties which have no existence at all until attributed by an observer (such as being suspected of a crime)[9]

## Properties and predicates

The ontological fact that something has a property is typically represented in language by applying a predicate to a subject. However, taking any grammatical predicate whatsoever to be a property, or to have a corresponding property, leads to certain difficulties, such as Russell's paradox and the Grelling–Nelson paradox. Moreover, a real property can imply a host of true predicates: for instance, if X has the property of weighing more than 2 kilos, then the predicates "..weighs more than 1.9 kilos", "..weighs more than 1.8 kilos", etc., are all true of it. Other predicates, such as "is an individual", or "has some properties" are uninformative or vacuous. There is some resistance to regarding such so-called "Cambridge properties" as legitimate.[10]

## Intrinsic and extrinsic properties

An intrinsic property is a property that an object or a thing has of itself, independently of other things, including its context. An extrinsic (or relational) property is a property that depends on a thing's relationship with other things. The latter is sometimes also called an attribute, since the value of that property is given to the object via its relation with another object. (See the etymology of the word on Wiktionary.) For example, mass is a physical intrinsic property of any physical object, whereas weight is an extrinsic property that varies depending on the strength of the gravitational field in which the respective object is placed. other examples are the name of a person (an attribute given by the person's parents) and the weight or mass of the person.

## Relations

A relation is often considered[by whom?] to be a more general case of a property. Relations are true of several particulars, or shared amongst them. Thus the relation ".. is taller than .." holds "between" two individuals, who would occupy the two ellipses ('..'). Relations can be expressed by N-place predicates, where N is greater than 1.

It is widely accepted[by whom?] that there are at least some apparent relational properties which are merely derived from non-relational (or 1-place) properties. For instance "A is heavier than B" is a relational predicate, but it is derived from the two non relational properties: the mass of A and the mass of B. Such relations are called external relations, as opposed to the more genuine internal relations.[11] Some philosophers believe that all relations are external, leading to a scepticism about relations in general, on the basis that external relations have no fundamental existence.[citation needed]