Nominalism

Nominalism is the believe, that no universals exists, no abstract properties, relations or types, but only particular things. Everything that does exist exists in space and time.

Some nominalists belief, that only general terms or names exists - but no qualities they refer to. A general term refers to a specific object or a collection of objects. So if we talk about ``yellowness'', this might refer to a specific banana, a collection of some bananas and lemons and cars or the collection of all yellow things on the world.

If we consider 20 beer, then all they have in common is that they are ``called'' beer, but no quality of just being ``beer''. However, there must be a reason for calling a certain beer ``beer''. It is the ingredients, hop, malt, water, the taste, the aroma, the color, the look, that lets us identify a beer. The question nominalists have to answer is, why beers appear to have certain qualities in common, although they do not.

If we refer to the yellowness of a banana, we certainly do not refer to the banana itself, but to the property of being yellow. Nominalists deny the existence of instances of properties or relations. However, even if we cannot experience an abstract thing like ``yellowness'', at least we can experience an instance of it. How this is possible is another question that has to be answered by nominalists.

There are some weaker forms of nominalism, namely imaginism and conceptualism. Both still deny that universals exists. Imaginism is the believe, that ``universals'' are pictures in mind. One can picture a banana in mind, the look, the smell, but it does not mean, that it is a concept of what a banana really is. Conceptualism is the view that universals are concepts and individual objects are instances of concepts in mind.

Another and the last here mentioned approach to nominalism is called ``ostrich nominalism''. In sentences as $\mathbf{a}$ is $F$, ostrich nominalism takes $\mathbf{a}$ alone to be the truth-maker for these sentences. Asked why two bananas are both called banana, an ostrich nominalist would answer that they both do not have any entity in common, but however are both bananas, one cannot analyze further.