The debate surrounding universals focuses on the question of whether they have any status outside of the mind. But what do we mean by universals which are often contrasted with particulars? 

Most people tend to think that the world consists of particulars or singular objects that exist in only one place at a time; for example, a particular strawberry or a particular apple. But many particulars seem to share characteristics. The strawberry and apple, for example, are both red. But why and how are they both red? Such a question continues to fascinate philosophers and has led them to fall into one of three groups. There are realists who posit universals as objectively existing entities that particulars (like strawberries and apples) share in. Then there are anti-realists who fall into the conceptualist and nominalist camps, both of whom do not accept universals and deny that they are needed.

Realism maintains that universals exist and that without them we will be unable to explain a fundamental fact of reality, namely, that there is genuine commonality and systematicity in nature. There are at least two types of realism: extreme and strong. Extreme realism goes back to Plato. On Plato’s view, to explain the identity of distinct particulars, one must accept that there is another entity besides the resembling particular, the universal, which Plato called a Form. So, that an apple and a strawberry are both red is because they both share in the universal red or the Form of Red. The Form of Red manifests itself in both those particulars at once. 

On extreme realism, there are at least three different components (which we can view as a triad): the particular (the particular apple or strawberry), the red of the particular, and the Form of Red that manifests itself in the particular. Plato viewed the Forms as immaterial (they exist outside of space and time) but also somehow related to the particulars in which they are apparent. In other words, the Form of Red must be somehow related to the red apple because it makes the particular apple red. Plato theorized that particulars participate in Forms and receive their qualities by virtue of this relation of participation. This view has, however, become the victim of some serious criticism, especially from the Third Man Argument that has led many philosophers to explore alternatives.

Strong Realism rejects the independent existence of Forms. In particular, it rejects the triad posited by extreme realism. When a particular object has a quality, there is simply the particular (the apple) and its quality (its redness). There is just the apple and its redness, but no third independent Form of Red needed to ground possession of the quality. For the strong realist, a universal is just the quality that is in this particular and any other identical particulars. The universal red is in this apple, that apple, and all apples that are similarly red. It is not distinct and independent from the particular that have this color, but because it is a universal it can exist in many places at once. The strength of this view is that it is immune to the Third Man Argument and does not need to posit abstract Forms existing outside of space and time to ground the qualities of particulars. The Strong Realist’s universals are in space and time, and can be in many places at once. 

Conceptualism maintains that what we consider to be a universal is a feature of the mind and the concepts or ideas in minds. Similarity among particulars is accounted for by appealing to general concepts or ideas: the apple and the strawberry are red because the concept of redness applies to both particulars. Red is not an abstract object or Form, but a concept that many diverse particulars fall under, or conform to.

Nominalists maintain that only particulars exist and deny the existence of abstract and universal concepts. Predicate nominalism says that a particular, say, a table is red because the predicate “is red” can be truly said of the table. The predicate “is red” is merely a sequence of words on a page. Expanding this approach, one can say that two red particulars (an apple and a table) are red simply because the linguistic expression, the predicate “is red,” is said of both. The proponent of this view claims that all that exists are individuals and words for talking about those individuals. A major criticism of predicate nominalism is that it does not solve the Problem of Universals because it ignores the question. Why, for example, is it true to say that both the apple and car are red and not green or blue?

Another form of nominalism, resemblance nominalism, collects particulars into sets based on their resemblance and then accounts for their identity and resemblance by appeal to commonalities of the set membership. On this view, a particular’s redness is explained by it belonging to a set of red things. The fact that two particulars are both red is explained by them belonging to the same set of red things. For instance, a red apple that resembles other red apples, red shirts, and red cars would go into a set. A given set, such as the set of red things, is constructed by adding to it particulars that resemble each other more closely than they resemble any non-members (particulars that aren’t red). Thus, shared qualities are accounted for by talking only about resemblance relations.

References and Recommended Readings

MacLeod, Mary., and Rubenstein, Eric. n.d. Universals. Available.

Garvey, James., and Stangroom, Jeremy. 2012. The Story of Philosophy: A History of Western Thought. London: Hachette UK.