Theory of Descriptions - Introduction

Introduction

Bertrand Russell's theory of descriptions was initially put forth in his 1905 essay "On Denoting", published in the journal of philosophy Mind. Russell's theory is focused on the logical form of expressions involving denoting phrases, which he divides into three groups:

1. Denoting phrases which do not denote anything, for example "the current Emperor of Germany".
2. Phrases which denote one definite object, for example "the present President of the U.S.A." We need not know which object the phrase refers to for it to be unambiguous, for example "the cutest kitten" is a unique individual but his or her actual identity is unknown.
3. Phrases which denote ambiguously, for example, "an Aardvark".

Indefinite descriptions constitute Russell's third group. Descriptions most frequently appear in the standard subject-predicate form.

Russell put forward his theory of descriptions in order to solve a number of problems in the philosophy of language. The two major problems are (1) co-referring expressions and (2) non-referring expressions.

The problem of co-referring expressions originated primarily with Gottlob Frege as the problem of informative identities. For example, if the morning star and the evening star are the same planet in the sky (indeed, they are both the planet Venus), how is it that someone can think that the morning star rises in the morning but the evening star does not? This is apparently problematic because although the two expressions seem to denote the same thing, one cannot substitute one for the other, which one ought to be able to do with identical or synonymous expressions.

The problem of non-referring expressions is that certain expressions that are meaningful do not truly refer to anything. For example, by "any dog is annoying" it is not meant that there is a particular individual dog, namely any dog, that has the property of being annoying (similar considerations go for "some dog", "every dog", "a dog", and so on). Likewise, by "the current Emperor of Germany is gray" it is not meant that there is some individual, namely the current Emperor of Germany, who has the property of being gray; Germany is no longer a monarchy, so there is currently no Emperor. Thus, what Russell wants to avoid is admitting mysterious non-existent entities into his ontology. Furthermore, the law of the excluded middle requires that one of the following propositions, for example, must be true: either "the current Emperor of Germany is gray" or "it is not the case that the current Emperor of Germany is gray". Normally, propositions of the subject-predicate form are said to be true if and only if the subject is in the extension of the predicate. But, there is currently no Emperor of Germany. So, since the subject does not exist, it is not in the extension of either predicate (it is not on the list of gray people or non-gray people). Thus, it appears that this is a case in which the law of excluded middle is violated, which is also an indication that something has gone wrong.