Editing Philosophical Investigations (section)

=== Private language ===
{{Main|Private language argument}}
Wittgenstein also ponders the possibility of a language that talks about those things that are known only to the user, whose content is inherently private. The usual example is that of a language in which one names one's sensations and other subjective experiences, such that the meaning of the term is decided by the individual alone. For example, the individual names a particular sensation, on some occasion, ''S'', and intends to use that word to refer to that sensation.<ref>§&nbsp;243</ref> Such a language Wittgenstein calls a ''private language''.

Wittgenstein presents several perspectives on the topic. One point he makes is that it is incoherent to talk of <em>knowing</em> that one is in some particular mental state.<ref>§&nbsp;246</ref> Whereas others can learn of my pain, for example, I simply <em>have</em> my own pain; it follows that one does not <em>know</em> of one's own pain, one simply <em>has</em> a pain. For Wittgenstein, this is a grammatical point, part of the way in which the language game involving the word ''pain'' is played.<ref>§&nbsp;248</ref>

Although Wittgenstein certainly argues that the notion of private language is incoherent, because of the way in which the text is presented the exact nature of the argument is disputed. First, he argues that a private language is not really a language at all.  This point is intimately connected with a variety of other themes in his later works, especially his investigations of "meaning". For Wittgenstein, there is no single, coherent "sample" or "object" that we can call "meaning". Rather, the supposition that there are such things is the source of many philosophical confusions. Meaning is a complicated phenomenon that is woven into the fabric of our lives. A good first approximation of Wittgenstein's point is that meaning is a <em>social</em> event; meaning happens <em>between</em> language users. As a consequence, it makes no sense to talk about a private language, with words that ''mean'' something in the absence of other users of the language.

Wittgenstein also argues that one couldn't possibly <em>use</em> the words of a private language.<ref>§&nbsp;256</ref> He invites the reader to consider a case in which someone decides that each time she has a particular sensation she will place a sign ''S'' in a diary. Wittgenstein points out that in such a case one could have no criteria for the correctness of one's use of ''S''. Again, several examples are considered. One is that perhaps using ''S'' involves mentally consulting a table of sensations, to check that one has associated ''S'' correctly; but in this case, how could the mental table be checked for its correctness? It is "[a]s if someone were to buy several copies of the morning paper to assure himself that what it said was true", as Wittgenstein puts it.<ref>§&nbsp;265</ref> One common interpretation of the argument is that while one may have direct or privileged access to one's <em>current</em> mental states, there is no such infallible access to identifying previous mental states that one had in the past.  That is, the only way to check to see if one has applied the symbol ''S'' correctly to a certain mental state is to introspect and determine whether the current sensation is identical to the sensation previously associated with ''S''. And while identifying one's current mental state of remembering may be infallible, whether one remembered correctly is not infallible. Thus, for a language to be used at all it must have some public criterion of identity.

Often, what is widely regarded as a deep philosophical problem will vanish, argues Wittgenstein, and eventually be seen as a confusion about the significance of the words that philosophers use to frame such problems and questions. It is only in this way that it is interesting to talk about something like a "private language"{{snd}}i.e., it is helpful to see how the "problem" results from a misunderstanding.

In summary, Wittgenstein asserts that if something is a language, it <em>cannot</em> be logically private; and if something <em>is</em> private, it is not (and cannot be) a language.