Private language argument

The private language argument is a family of considerations, developed by Ludwig Wittgenstein in Philosophical Investigations (PI), aiming to show that a language whose expressions are, in principle, understandable by only a single individual is unintelligible. In PI the idea is introduced at §243 and examined chiefly in §§244–271, with related remarks continuing to §315.^[1][2] These remarks are not a single formal proof but a sequence of interlocking moves, examples, and reminders. The central conclusion is commonly put this way: a necessarily private language—one whose meanings are fixed by items only the speaker can access—cannot establish the standards of correct/incorrect use required for meaningful language.^[2]

Scholars distinguish Wittgenstein's target from mere ciphers or idiolects: a secret code could in principle be decoded or taught to others, whereas a private language, as defined here, is in principle unlearnable and untranslatable by anyone else.^[2] The topic has been central to late 20th-century debates on meaning, mind, rule-following, and the social character of language.^[3][4]

Significance

Wittgenstein's discussion challenges pictures that ground meaning in private, self-intimating mental items (for example, some interpretations of John Locke and later "language of thought" views).^[2][5] If the idea of a private language collapses, then the very possibility of concept formation and linguistic understanding depends on forms of human agreement and shared practices—on what Wittgenstein calls our "forms of life."^[1] This bears on epistemology (skepticism about other minds), philosophy of mind (the status of sensations and qualia), and the methodology of cognitive science.^[2]

Overview of the argument in Philosophical Investigations

Scope and definition (PI §§243–257)

Wittgenstein contrasts ordinary talk about our experiences with a hypothetical language whose words "are to refer to what only the speaker can know—his immediate private sensations."^[1] Natural languages are not private in this sense because expression, training, and public criteria are integral to their use. Simply subtracting expressions of sensation from a public language does not yield a private one; the question is whether meaning could be fixed in a purely private way.^[2]

The diary case (PI §258)

Wittgenstein imagines keeping a diary: whenever a certain recurring sensation occurs, the subject writes "S." Could the subject have defined S by privately "pointing" (attending) to the sensation and associating the mark with it? He argues that:

• If S just means "whatever I now feel," then "whatever seems right to me is right," and the contrast between correct and incorrect use collapses—so there is no rule to follow.^[1][2]
• If S is supposed to mean "the same sensation as before," appeal to "remembering the connection correctly" presupposes that there was a determinate earlier correlation—precisely what is at issue in a purely private setting.^[1][3]

This is not a skeptical argument about the reliability of memory; it is a point about the intelligibility of correctness where no independent criteria exist. As Wittgenstein quips, relying on an "imaginary dictionary" to check a translation is "as if someone were to buy several copies of the morning paper to assure himself that what it said was true" (PI §265).^[1][2]

Public anchoring (PI §§270–271)

Suppose the diarist ties uses of "S" to a manometer reading (e.g., blood pressure rising). Now the correlation can be checked, but what has been secured is a public use—roughly "blood pressure rising" or "sensation characteristic of a BP rise." The "private object," even if postulated, drops out as irrelevant to meaning.^[1][2]

Beetle-in-a-box (PI §293)

Wittgenstein asks us to imagine each person has a box with a "beetle" no one else can see. Whatever is in the box plays no role in the use of the word "beetle"; the public practice determines its grammar. Likewise for pains: if we model sensation language on "object and designation," the "object" becomes idle in determining meaning.^[1]

Rule-following background (PI §§198–202)

The private language discussion sits within Wittgenstein's broader rule-following considerations. Any finite course of action can be made to accord with a rule on some interpretation (PI §201), so following a rule is exhibited in our practices, where we distinguish obeying a rule from merely thinking we are (PI §202). That contrast cannot be constituted by a purely private "standard."^[1][4]

Objections and replies

"Memory skepticism" vs. "meaning/criterion" readings

A traditional ("Orthodox") reading made the diary case turn on fallible memory; critics then replied that memory can fail publicly as well.^[3] Contemporary interpreters argue this mislocates the issue: Wittgenstein challenges the very sense of correctness where there are no independent criteria—so the problem is not about how well we remember but about what would count as remembering correctly in the first place.^[2][6]

Self-defeating, rules out public language

The argument does not self-defeat and rule out public language. The move from "no private criteria" to "no criteria at all" is a non sequitur. Public practices furnish the relevant standards of correctness; the argument is precisely that only such practices can do this job.^[2]

The "community view" and the Crusoe question

Some infer that language is essentially social (the "community view"). Others hold that Wittgenstein shows language must be potentially social: even a lifelong Robinson Crusoe could have meanings only insofar as his environment provides determinate, publicly-typeable standards for use (not because he consults his "inner light").^[7][8] The textual issue is contested, but many commentators agree that the argument at least establishes the potential sociality of language.^[2][9]

Historical background and targets

Wittgenstein's target overlaps with views that treat meanings as inner entities fixed by acquaintance. Bertrand Russell explicitly envisaged a largely private vocabulary for proper names of sense-data in a "logically perfect language."^[10] Later Fodor proposed that communication proceeds by translating between inner mentalese tokens and public speech.^[5] Wittgenstein's challenge asks what fixes such inner tokens' meanings if not public criteria.^[2]

Kripke's interpretation and the rule-following "paradox"

In Wittgenstein on Rules and Private Language (1982) Saul Kripke develops PI §201 into a global skepticism about meaning ("Kripkenstein"). He illustrates with "quus," defined to match plus until numbers ≥57 appear, then yield 5; the worry is what fact determines that a speaker means plus rather than quus. Kripke offers a "sceptical solution" in terms of assertibility conditions rooted in communal practice.^[11] The reading is influential and controversial; many argue it misrepresents Wittgenstein's therapeutic aims and his treatment of "facts" and truth-conditions.^[4][12] Either way, Kripke's discussion revived the community-view debate and reframed the private-language issues in terms of rule-following.^[2]

Method and recent interpretive trends

Beyond "Orthodox" vs. Kripkean readings, recent work contrasts "resolute/Pyrrhonian" interpretations—which treat philosophical theses in PI as tempting nonsense to be dissolved—with "substantial/non-Pyrrhonian" readings that attribute positive doctrines about grammar and meaning. These methodological stances color how one reads the private-language passages: as showing that the very idea is nonsense (no determinate sense can be given to "a language only I could understand"), or as yielding a substantive (false) thesis.^{[13][14][15][16][17]} Mulhall, for example, argues that both strands can be discerned, though he favors a resolute reading.^[17]

Related themes

• Pain and expression: PI §281 stresses that predicates like "sees," "is in pain," and "conscious" attach to living beings and their characteristic patterns of behavior; the grammar of sensation language is tied to expression and criteria, not inner ostension.^[1]
• Numbers and rules: Wittgenstein parallels the private-language discussion with earlier remarks on rule-following and mathematics (PI §§185–242), challenging the idea that meanings or formulas determine their applications independently of training and practice.^[1]
• Tractatus connections: Some (e.g., Diamond) see anticipations in the Tractatus Logico-Philosophicus concerning private objects; others (e.g., Child) resist projecting later themes onto the early work.^[18][19]

See also

• Intrapersonal communication (i.e., "talking to oneself")
• Beetle in a box
• Rule-following
• Philosophy of language
• Philosophy of mind

Notes

In Part I of PI remarks are cited with "§"; Part II by Roman numeral or page in the 3rd/4th eds.^[1]