A nominalist denies that there are universals and the big motivator for this is the view that belief of our metaphysics should be based on the simplicity of theory. The idea is that if you have two theories that have the same explanatory power, the one that has fewer irreducibly distinct kinds of things is preferable.
The Motivation for Nominalism
Nominalists deny there are universals, but why? There isn’t a single answer ,but here are a few:
- Multiple exemplifications: The view is incoherent that different particulars can exemplify one and the same universals as others.
- It is impossible to provide a noncircular account of the identity conditions for things like properties, kinds and relations.
- Realism is regressive: Realists find themselves in an infinite regress by explaining attribute agreements by properties, kinds and relations.
A lot of this critique is based on the notion that universals occupy space. Bertrand Russell denies that universals have any location at all. Being north of is no spatial location for being north of.
The theory that only concrete particulars exist. For example, individual persons, individual plants, individual animals, etc. There are varying degrees of philosophers with this austere version. There are very scientific ones that is of an eliminativist stripe that holds only things proven by physics exist.
So how is something like yellow explained? Well since some objects are yellow and there are no facts to explain that. They just are. Essentially, what makes a is F true is that a is F.
Also with dealing with realist sentences like:
(1) Red is a color
Is replaced by
(1a) Red objects are colored red.
This version of nominalism believes it can have the simplicity of austere nominalism ontology and the explanatory simplicity of realism. They agree with the austere nominalist that there are only particulars, but reject the analysis of abstract reference.
The only real difference between austere and the metalinguist is the idea that it’s a matter of language claims rather than the nonlinguistic objects language is about. Wildred Sellar came up with a system for translating realist sentences into something that fits metalinguistic.
Unlike the last two theories, this theory holds that in addition to concrete particulars, there are such things as attributes, but deny they are multiply exemplifiable entities. Essentially things like colors are particulars. So a ball can be red, but it is a red nothing else can have. Same thing with the shape of the ball.
A more radical claim is that sentences that reference existence of universals are false.
The ball is red is false.
Unlike the austere nominalist who will translate a sentence, the fictionalist will not. This particular form of nominalism has grown in popularity recently.