The concept of a private language has been approached in different ways by different theorists and researchers. Numerous philosophers in the last half of this century have asked whether there can be human languages that are private. John Locke held in 1660 that private languages are possible and indeed necessary. He held in fact that every language is necessarily private and that the meaning or signification of words having a meaning is necessarily an idea in the mind of the speaker. For Locke, a word cannot signify something in the mind of the speaker and in the mind of the listener as well. If that were true, then the world would both immediately signify either something in someone else's mind or a physical object, meaning that the speaker would mean by his or her words something of which he or she had no knowledge. Locke says that language has as its immediate purpose making each person's private and invisible thoughts known to others. Opponents of Locke use his own statements to refute the idea that a private language is even possible, for if a word signifies only the idea of the speaker, then no one can ever know anyone else's ideas (Martinich 443-444). An examination of the views of various philosophers on this subject should clarify the issues.
Martinich defines a private language as a language in which the meanings of the words refer to entities to which only the speaker could have access (Martinich 444). A.J. Ayer simply assumes that there can be such a thing as private languages because there are such things as private languages, and he offers his definition a well:
A language may be said to be private when it is devised to enable a limited number of persons to communicate with one another in a way that is not intelligible to anyone outside the group (Ayer 449).
This would mean that slang and family jargon would be a private language. Ayer is not in agreement that there is a private language accessible only...