The Problem of Universals

If I look out my window, point at a thing and call it a tree, how did I know that this object is a tree? A simple answer might be "it looks like a tree". In fact there is a delightful line in Mark Twain's Diary of Adam and Eve to this effect:

"Entry in Adam’s diary:

Tuesday: Been examining the great waterfall. It is the finest thing on the estate, I think. The new creature [Eve] calls it Niagara Falls – why, I am sure I do not know. [She] Says it looks like Niagara falls. That is not a reason, it is mere waywardness and imbecility."

How can a thing 'look' like Niagara Falls. For that matter, how can a thing 'look' like a tree. What we are really saying is that we have been shown instances of trees in the past and this new thing is similar to those instances. But this observation does not get us very far. There is a general category called 'tree' and we believe that this object outside the window belongs to that category. But, where did that category come from? And, how do we know the thing we are pointing at belongs to that category?

The problem of getting from the individual occurrences of things in the world to the groups into which we organize them is known as The Problem of Universals. The things that make up the instances or occurrences in the world are known as particulars and the groups into which we organize them are known as universals.

Why is the problem of universals so important? Consider the definition of a triangle. It is a three sided geometric figure the sum of whose interior angles is 180 degrees. That is a great definition. All triangles are included and nothing is included that is not a triangle. And from such precise definitions whole fields of knowledge have been developed. Now consider what would happen if we defined a triangle to include other geometric objects such as polygons, and metaphorical uses such as a 'love triangle'. How far could geometry get with definitions like that? And that is the crux of the issue. Defining universals is at the very heart of how we develop our knowledge of the world. And without well defined universals, progress in discovering knowledge is seriously hampered.

Since this is such a crucial problem in the advancement of knowledge we are going to stay with it for a while. While it is tempting to just move on with our understanding of games, not getting the concept nailed down threatens anything we would do from this point on. It would be like saying, let's not bother pouring a concrete foundation for this house. Let's just start putting up the walls. Whether or not you fully grasp the Problem of Universals, I think you can easily see where the analogy would take you.