(citation) Bertrand Russel, as of 1919, provides a tertiary conditional for the meaning of definite article, the. For "the A (A being a description which means having the property a)" to result in a true decsription, the satisfiable conditions he puts forth are that at least one object must satisfy a, at most one object must satisfy a, and if an object c satisfies a, then c is "the A." This portrait illustrates the propositional meaning of "the." It leaves the possibility open for unreal definite phrases in which the referrent is false. Say, "the man in the moon" is hollow, and the phrase "the inhabitant of London" (Russell's own example) is reductive.
Russell's treatment of the definite article concerns its meaning and how such a statement is to be mapped to a truth value. However, there is a further question regarding the production of such descriptions and why they come about. For example, I look outside. I see a green umbrella and a grey umbrella. As far as my regular existence goes prior to today, I would have only said, "the green one" or "the grey one." Only when considering Russell's writing did I eventually produce the thought, "what about the red one?" Now, if I were to say, "Bob is sitting under the red umbrella over there," with there being where my eye sees, I would be speaking against reality. However, such a statement was possible for me to say only in the case of my producing the possibility of a red umbrella. (See previous discussion of Neon-Green Pigeons.)
In using "the," one fundamental aim is to clarify between two similar cases. "Don't go through the back door; go through the front one." Another purpose of "the," more auxiliary, is to instantiate a relative collective position. People living together say, "we need to clean the kitchen," even though they all know they share one kitchen, and the statement "we need to clean kitchen" could get enough of the point across. In this case, "the" indicates: "1) we know what a kitchen is; 2) we know there are many kitchens; 3) we know our kitchen is a particular shared instance of kitchens." In this way, "the" serves to fulfill an idea of "one instance of a general case that we both know of and one which we are aware pertains to our locality and not others." Consider: "Kid, go to school," versus "kid, go to the school." Or, "I see fireworks" or "I see the fireworks." Another function of "the" is "the same as has been discussed." Consider a story: "Once upon a time, there was a dog. A man came upon the dog..."
In approaching the definite article from end of statement-production, the question of unreality which Russell irons out has yet to appear at all. For, in earnest usage of language, the usage of the word "the" arises out of a need to describe what is being perceived. Then, what of instances of people using definite articles to describe nonexistent things? Who speaks of "the round square" except he who wishes to speak on an entity which contradicts certain principles? The invocation of "the round square" can simply mean "that shape which fulfills two conditions, that the center is of equal distance to the points on the circumference and that all four sides of the shape are equal." However, who would think to put these two things together except those who perceived a circle and a square individually, understood them to be existent in-and-of-themselves, then spoke on contradicting things within these two shapes.
In another example, who speaks of "the present king of France" except he who either has come to believe that there is one, or he who constructs an entity which both is a continuation of a French kingly lineage and also exists during a time after which the monarchy was dissolved. Perceiving the contradictory nature of different modes of existence, one may speak on that which runs against nature. Russell, for instance, is able to mention "the present king of France" at all, as am I able to mention it, because he is writing on the topic of unreality, using conditions to demonstrate what brings unreality about. In the former case of the believer in a present king of France, one can argue that there must be some symbol or image which inspires him to believe such a thing, perhaps indiosyncratically so. Nonetheless, there exists a referrent to what he means when he says, "the present king of France." In the latter case, there also exists a referrent to what he means, which is "that which contradicts itself." In both cases, are the speakers speaking on unreality? One can argue that in the realm of propositional logic, yes. But, in the realm of communication and how these statements come about, the question becomes more complicated. There is a difference between what their statements mean and what they mean by their statements, apart from intent, relative to perception and reconstruction of images.
To return to the example of the "red umbrella," such an entity came about when I said to myself, "there are two umbrellas. What is an umbrella that contradicts the existence of these two umbrellas?" To which the color red came to mind. Thus a concrete ordered pair is created, (umbrella, red). This ordered pair is true in that it exists. In this way, in discussing definite articles, one can bypass the theory of possible worlds and general vs. specific existences, by treating things as they manifest in the world through human perception and that which contradicts what is there.