Aristotle's theory of universals

Aristotle's theory of universals (T-H-L-F-C)

15:51, 25 February 2002	15:11, 19 April 2014 (190 edits and 12 years later)
Aristotle's theory of universals is one of the classic solutions to the problem of universals. Aristotle thought--to put it in a not-very-enlightening way--that universals are simply types, properties, or relations that are common to their various instances. On Aristotle's view, universals exist only where they are instantiated; they exist only in things (he said they exist in re, which means simply "in things"), never apart from things. Beyond this Aristotle said that a universal is something identical in each of its instances. So all red things are similar in that there is the same universal, redness, in each red thing. There is no Platonic form of redness, standing apart from all red things; instead, in each red thing there is the same universal, redness.	Aristotle's theory of universals is one of the classic solutions to the problem of universals. Universals are types, properties, or relations that are common to their various instances. In Aristotle's view, universals exist only where they are instantiated; they exist only in things (in Latin, it is said they exist in re, which means "in things"), never apart from things. Furthermore, Aristotle said that a universal is identical in each of its instances. So all red things are similar in that there is the same universal, redness, in each thing. There is no Platonic Form of Redness, standing apart from all red things; instead, each red thing has a copy of the same property, redness.
Hence, Aristotle disagreed with Plato's brand of realism by saying that universals do exist in space and time. They exist all around us, rather than in some Platonic heaven.
To further flesh out Aristotle's theory of universals, it is useful to consider how the theory might satisfy the constraints on theories of universals listed in the problem of universals article.	To further flesh out Aristotle's theory of universals, it is useful to consider how the theory might satisfy the constraints on theories of universals, (see problem of universals).
First of all, on Aristotle's view, universals can be multiply instantiated. Aristotle stresses, after all, the one and the same universal, applehood (say), that appears in each apple. Common sense might detect a problem here. (The problem can arise for other forms of realism about universals, however.) Namely, how can we make sense of exactly the same thing being in all of these different objects?	First of all, on Aristotle's view, universals can be instantiated multiple times. Aristotle stresses, after all, the one and the same universal, applehood (say), appears in each apple. Common sense might detect a problem here, a problem that can arise for other forms of realism about universals as well, namely: how to make sense of what is exactly the same in all of these different things?
That after all is what the theory says; to say that different deserts, the Sahara, the Atacama, and the Gobi are all dry places, is just to say that the exact same being, the universal dryness, occurs at each place. Universals must be awfully strange entities if exactly the same universal can exist in many places and times at once, or so one might think. But maybe that's not so troubling; it seems troubling if we expect universals to be like physical objects, but remember, we are talking about a totally different category of being. So a common defense of realism (and hence of Aristotle's realism) is that we should not expect universals to behave as ordinary physical objects do. Maybe then it is not so strange, then, to say that the exact same universal, dryness, occurs all over the earth at once; after all, there is nothing strange about saying that different deserts can be dry at the same time.	That, after all, is what the theory says: to say that different deserts, the Sahara, the Atacama, and the Gobi are all dry places, is just to say that each place is exactly the same (qualitatively) in terms of dryness, or in so far as being a dry place (not that each place is quantitatively dry to exactly the same degree). This may seem troubling if universals are thought to be like physical objects, but Aristotle is talking about a different category of being. So a common defense of realism (and hence of Aristotle's realism) is that we should not expect universals to separately behave as an ordinary physical object itself would do. To say the same universal, dryness, occurs simultaneously in all these places, after all, is nothing more strange than saying each place is dry, ex hypothesi.
Are Aristotelian universals abstract? And are they, then, what we conceive of when we conceive of abstract objects such as redness?	Are Aristotelian universals abstract? If so, then for example, how does one abstract the concept of redness from one or more red things?
Perhaps. It will help to explain something about how we form concepts, according to Aristotle. We might think of a little girl just forming the concept of human beings. How does she do it? When we form the concept of a universal on Aristotle's theory, we abstract from a lot of the instances we come across. We as it were mentally extract from each thing the quality that they all have in common. So how does the little girl get the concept of a human being? She learns to ignore the details, tall and short, black and white, long hair and short hair, male and female, etc.; and she pays attention to the thing that they all have in common, namely, humanity.	It will help to explain something about concept formation or generalization, according to Aristotle. Consider what a young child does, who is just on the verge of grasping a generic concept such as human being. The child is marshaling their memories of various encounters with a human specimen in such a way that the universal genus stands in for the essential similarity that stands out, on reflection, in each instance. Today, it might be said that one mentally extracts from each thing the quality that they all have in common. When the child gets the concept of a human being, he or she has learned to ignore the accidental details of their past experiences, (tall or short, male or female, etc.) and pay attention to the relevant quality they all have in common, namely, humanity.
On Aristotle's view, the universal humanity is the same in all humans (i.e., all humans have that exact same type in common); and this allows us to form a concept of humanity that applies to all humans.	On Aristotle's view, the universal humanity is a natural kind defined by the essential properties that all humans have in common.
Are Aristotelian universals the sorts of things we refer to when we use general terms, like 'redness' and 'humanity'? Again, perhaps. The idea is that when we refer to humanity, we refer to the type, human being, that appears identically in each human. We do not refer simply to all the humans, but instead the type, human being, which is the same in each human.
This obviously needs expansion--even just to become an adequate minimal presentation of Aristotle's theory.