One of the great philosophical dividing lines has always been the line that separates the particular from the universal – the unique from the general. We live in a world of both particulars and universals and philosophers have long argued over which is more real. Nominalists say that it is only the particulars that are real and that universals are simply mental devises for ordering particulars.
Take as an example a dog. You can see a brown animal with teeth barking in front of you. That particular thing is definitely real – but is it a dog? Dog is a category of things. The term dog stands for a set of characteristics that if satisfied by an animal makes it allowable to call that animal a dog. But is the category dog a real thing or just an idea?
A nominalist would say that it is just an idea; a realist would say that it is actually a real thing. Dog is an essence, a true essence of ‘dogness’ that is expressed imperfectly and partially through all particular dogs. In the same way human being is a real thing – a real essence of ‘human beingness’ that is expressed partially and imperfectly in each particular human being.
Where do particulars and universals exist? With particulars that is easy. Particular dogs and particular people exist in the sensual physical world. We actually see, touch, taste, hear and smell particulars. You can touch a particular house like the one I grew up in, but you can’t touch house in general. If the universals are real this opens up a perplexing question, where do they exist?
This is a challenging philosophical issue. Idealists would say that these universals exist in some ideal realm of thought. To an idealist ideas and the realm of thought in which they exist are real, they are a kind of stuff. Materialists don’t buy that. Materialists say that only the physical world of the senses is real and that ideas are a bi-product of the interaction of the physical neuro-chemical components of the brain. This of course doesn’t satisfactorily answer the question because it still leaves you not knowing what an idea actually is.
The American Pragmatists George Herbert Mead and John Dewey thought that they had figured out where universals exist. They exist in language, in the ongoing conversation of society, what Mead referred to as the Universe of Discourse. If you see a particular animal in front of you that you don’t recognize and you think it might be a dog you would have to ask someone to find out. You could look in a book, but that would be essentially asking the author.
To find out what universal category applies to a particular instance you have to reach into the universe of discourse for the answer. You can’t sit there and figure it out. If you were an expert on dogs you might be able to figure it out just by examining more carefully, but the only way you would have become an expert is by having internalized a great deal of what society knows about dogs. That part of the universe of discourse would exist in your head, which is what makes you an expert. You are not really an expert on dogs. You are an expert on what society thinks about dogs.
We live in a world of particulars and universals. The particulars exist in the physical world of the senses and cannot be denied. According to the Pragmatists the universals exist in the conversation of society.