I have briefly discussed the difference between sentences and definitions and explained how these were connected to concepts. But there are a number of objections resulting from a misunderstanding of the traditional position on these things.
Modern philosophers tend to make a number of mistakes when trying to understand concepts. They tend to think of concepts as “those behaviors, images and beliefs associated with a particular idea or word”. So they may try to define the concept red by every other concept associated with it, by the image of red in our minds and/or by the beliefs we have about redness. They may even define a concept by what causes us to have the concept! These methods carry over to their understanding of definitions and sentences because definitions and sentences are both composed of concepts.
The first misunderstanding of traditional definitions is that definitions fail to take into account the associations of that concept. For example, when people think of a “snake”, they think of a hissing, slimy animal with no legs. The problem is that snakes are not slimy. Simply because something is associated with a word in our mind does not mean that it is a part of the definition of that word. Definitions are not images, nor can they contain images. They are an intellectual understanding of reality not an exercise of our imaginations!
The second misunderstanding of traditional definitions is that we all have an explicit understanding of these definitions. This is by no means true. Our understanding of the world began at a very young age. As we grew up, we began to use words correctly, but lost the knowledge of their definitions. This is natural. For example, we learn how to play a game by learning the rules. Once we become really good at the game, we no longer think of the rules. We simply follow them. Our thoughts are now considering the best way to play the game we do not even notice the rules any longer. Language is similar. Once we learn our first concepts we no longer consider the meaning of them. We simply use them correctly to form the thoughts we are actually thinking about.
The third and final misunderstanding of traditional definitions is that definitions must exist formally or not at all. This is by no means true. Definitions such as “big chair” exist in ordinary language. Formal language exists in order to clarify and make explicit what already exists in natural languages. It also exists in order to define specialized words that do not exist in natural language.
The traditional understanding should be quite clear. Concepts can be combined to form either definitions or sentences. Therefore, all natural languages and all formal languages are composed of definitions and sentences. Every definition can be broken down into self-evident concepts or other definitions. Every sentence can be broken down into self-evident sentences, definitions, other sentences, or is itself self-evident. So the basic building blocks of sentences and definitions are self-evident concepts and self-evident sentences. No concept, definition or sentence has anything that can be imagined as a part.