The " Fido "-Fido theory, advocated by Bertrand Russell, identifies the meaning (content) of an expression and the entity it represents (its reference, understood in the realistic sense and not in the sense of an intentional object). The content of the proper noun " Fido " is its bearer, i.e. my dog Fido. Similarly, the content of a predicate is a "universal" (property or relation), and the content of a statement is a state of affairs. Although the name " Fido "-Fido theory has been introduced to deride it, it is an important theory, because it is in relation to it - in relation to its alleged shortcomings - that more complex theories based on distinctions between levels or types of meaning/content,such as those of Frege or Strawson, are developed. What's more, the content level it foregrounds does indeed play a leading role - a foundational role - in relation to the other levels of meaning postulated by more complex theories.
Definite descriptions (" le F ") do not behave as they should according to the " Fido "-Fido theory: the absence of a referent does not render them devoid of content. (For example, Victor Hugo's book on the Battle of Waterloo is interesting, even if it doesn't exist) Russell responded to this objection by distinguishing definite descriptions from genuine singular terms, such as this book. The latter designate individual objects, whose identification they impose; we therefore don't really understand a statement like This book is interesting if we don't identify the book we're talking about. But, Russell argues, descriptions have another logical function, akin to quantifiers. If Russell is right, the " Fido "-Fido theory is not refuted by objectless definite descriptions, since the semantic contribution of a quantifier is not an object but (according to contemporary semantics) a higher-order property.
Strawson objected to Russell that even a sentence like This book is interesting retains its linguistic meaning in the absence of any real object corresponding to this book. Strawson thus rejects the " Fido "-Fido theory and distinguishes two levels of meaning: the linguistic meaning of a standard expression, corresponding to its function, and the referential content conveyed in context. Nonetheless, Russell is right to emphasize the direct referential relationship between an expression like this book and an entity in the environment, a relationship that distinguishes authentic singular terms from descriptions. The notion of linguistic meaning or function that Strawson invokes to dismiss the " Fido "-Fido theory itself presupposes this direct relation of reference that lies at the heart of the theory in question: indeed, for Strawson, the function of an expression like this book is to refer to a given book-like entity in the environment. The starting point, then, must be the realistic, relational notion of reference that the " Fido "-Fido theory emphasizes.
