Identification (logic)

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In the philosophy of language, expressions of the form “der / die / das A” are referred to as identifiers , also specific or definite descriptions ( English (definite) descriptions ) .

Examples

  • the first man on the moon
  • the highest mountain on earth

These two expressions meet the so-called “uniqueness condition”, which one always thinks of as associated with labels: there is exactly one A, in the example: exactly one first person on the moon, exactly one highest mountain on earth.

The uniqueness condition can itself be analyzed as a conjunction of two conditions:

The uniqueness condition does not have to be fulfilled for every label. Examples of such so-called empty labels are:

The expression “the current king of France” violates the condition of existence, because there is currently no king in France, and the expression “the author of the Principia Mathematica” violates the uniqueness condition, because there is not just one author of this work, but two ( Bertrand Russell and Alfred North Whitehead ).

In the literature of the philosophy of language there is a whole series of characterization theories that deal primarily with the case of the unfulfilled uniqueness condition. If these theories are available in a formalized form, they usually use a lower iota as the identification operator (hence the iota operator ):


can be read as: “the x for which F (x) applies”.

Labeling theories

Thank God Frege

Gottlob Frege deals with the problem of labels in his essay “ On Sense and Meaning ”. For him, the fulfillment of the uniqueness condition is a prerequisite for both the truth and the falseness of a sentence with a label. The sentence “The current King of France is bald” would be neither true nor false for Frege. According to Frege, the fact that it is possible to form blank labels is an “ imperfection of language ”. For the formal languages of logic and mathematics , he demands that it should be made impossible to form empty labels by stipulating, for example, that a label “the A”, in which there is not exactly one A, is placed on a previously determined object , such as the number 0. So it is forced that the uniqueness condition is ultimately always fulfilled.

Bertrand Russell

Bertrand Russell takes a slightly different approach: For him, a sentence like

The current king of France is bald.

a logical analysis can be assigned in which the identification expression no longer occurs. His suggestion for an analysis is:

There is exactly one king of France and this one is bald.

In contrast to Frege, who labeled a sentence with an empty label as neither true nor false, for Russell such a sentence is simply false. The negation of the above sentence, namely the sentence

The current king of France is not bald.

is, however, ambiguous for Russell . It can mean:

There is exactly one king of France and this one is not bald.

or

There isn't exactly one king of France who is bald.

The first of these sentences is also wrong, but the second is true. According to Russell et al., Sentences with an empty label can be used. U. even be true.

Peter F. Strawson

Peter F. Strawsons criticizes Russell that after his analysis it becomes with a sentence like

The current king of France is bald

among other things, claims that there is exactly one king of France. According to Strawson, this is not an assertion but a presupposition . That is, it is a requirement that must be met for the sentence to be meaningful at all. According to Strawson, the same also applies to the negative:

The current king of France is not bald

Here, too, the uniqueness condition must be met so that it is a meaningful sentence. Strawson's theory thus approaches the Freges.

See also

literature

  • Thank God Frege: About meaning and meaning. In: Journal for Philosophy and Philosophical Critique, NF 100, 1892, 25–50. Also in: Gottlob Frege: Function, Concept, Meaning. Five logical studies. Edited and introduced by Günther Patzig . Vandenhoeck & Ruprecht, Göttingen 1962. 38-63.
  • Bertrand Russell: On Denoting. Min 14, 1905. 479–493. Dt in: Wolfgang Stegmüller (ed.) Das Universalien-Problem , Darmstadt, 1978. 21–40.
  • PF Strawson: On Referring. Min 59, 1950. 320–344. German: Ursula Wolf : Proper names Frankfurt a. M. 1985. 49-126.

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