Argument Against Private Ostensive Definition

Overview and Background

The argument against private ostensive definition is a central component of Ludwig Wittgenstein’s broader private language argument in Philosophical Investigations. It targets the idea that an individual could fix the meaning of a term by a purely inner act of pointing to a private sensation—such as pain, a color-image, or a feeling—accessible only to that individual.

An ostensive definition is a definition given by pointing. For example, one might teach the word “red” by pointing to a series of red objects and saying “This is red.” Many philosophers had supposed that even if public ostension explains how we learn ordinary words, something analogous could happen in the privacy of one’s own mind. A person might, it is thought, focus inwardly on a particular recurring sensation and mentally “baptize” it with a word, such as “S” for a certain kind of pain.

Wittgenstein’s argument challenges the coherence of this picture. He does not deny that people can talk about sensations, but he questions whether the meaning of a sensation-term could be grounded in a one-off, private act of inner pointing, independent of any public criteria or shared practices.

Structure of the Argument

Wittgenstein’s reasoning can be reconstructed as follows:

1. Ostensive definition and rule-following
   In a standard case of public ostensive definition, the act of pointing is embedded in a rule-governed practice. Learning “red” by ostension is not simply a one-time mental association; it presupposes that the learner can distinguish correct from incorrect applications (for example, not calling blue things “red”). This is possible because there are shared criteria—agreements in practice about when the word applies.

2. The private case: the sign “S”
   Wittgenstein asks us to imagine a diarist who keeps track of a special inner sensation. Whenever this sensation occurs, they note it with the sign “S.” The proposal is that the inner act of attending to the sensation at the first occurrence fixes the meaning of “S” via a private ostensive definition.

3. Lack of independent correctness conditions
   The central difficulty arises when the diarist later asks, “Is this sensation now the same as what I originally meant by ‘S’?” To answer, they seem to rely only on how things now strike them. But there is no independent standard for correctness: any sensation that currently feels similar might be taken as “S,” and nothing stands in the way of calling that correct. There is no contrast between seeming right and being right, because the only available check is the very impression under scrutiny.

4. No criterion vs. no memory problem
   Wittgenstein emphasizes that this is not merely a problem of unreliable memory. Even if memory were perfect, the issue is that the concept of meaning something by “S” requires criteria of correctness independent of momentary impressions. In the private case, there is no such criterion: the person cannot distinguish “I follow the same rule” from “I merely think I follow the same rule.”

5. Rule-following collapses into mere regularity of feeling
   Because no standard exists beyond what the individual currently judges, the notion of rule-following—using “S” correctly in accordance with a prior determination—loses its grip. It becomes unclear what it would be for the diarist to be mistaken about their own use: whatever they do simply counts as right. The idea of a private ostensive definition thus fails to support the robust concept of meaning as involving norms of correct and incorrect use.

6. Conclusion
   Hence, Wittgenstein concludes, the very idea of fixing a word’s meaning by a purely private ostensive definition is incoherent (or at least deeply problematic). For language to function as rule-governed, there must be publicly accessible or socially shareable criteria that distinguish correct from incorrect applications. A purely inner pointing to a sensation cannot provide this.

Philosophical Significance and Criticism

The argument against private ostensive definition plays a pivotal role in debates over meaning, mental content, and the nature of language.

Proponents of Wittgenstein’s line of thought argue that:

• It illuminates how language is embedded in forms of life and shared practices, rather than grounded in isolated mental episodes.
• It undermines the idea that meanings are essentially inner objects to which words privately refer.
• It supports a use-based or practice-based conception of meaning: what gives a term its meaning is its role in a shared linguistic practice, not a singular act of mental labeling.

The argument has also influenced broader discussions of rule-following, especially in the work of Saul Kripke. Kripke’s interpretation (often called “Kripkenstein”) emphasizes that an individual’s dispositions cannot, by themselves, determine which rule they are following. Though distinct, this debate is closely connected to the issue Wittgenstein raises about criteria for correctness in the private case.

Critics, however, raise several challenges:

• Some contend that Wittgenstein’s reasoning proves too much, apparently making even first-person authority over one’s own sensations problematic. If no inner criterion is acceptable, skeptics ask, how can a person reliably say they are in pain?
• Others argue that a private ostensive definition could be supplemented by internal regularities or neural states that function as criteria, even if not publicly observable. On such views, there may be non-public but still objective standards of correctness.
• Defenders of representational theories of mind suggest that mental representations could play a rule-governed role independent of public language, thereby salvaging a version of private ostension.

These disputes leave the status of the argument controversial. Some philosophers accept it as a decisive refutation of the very idea of a purely private language grounded in inner ostension. Others interpret it more modestly, as a reminder of the limits of certain philosophical pictures of meaning, or reject it as based on a questionable conception of rules and criteria.

In contemporary philosophy, the argument remains a touchstone for examining how far meaning and normativity can be individualized, and where—if anywhere—public practices become indispensable for language and thought. It continues to shape discussions of introspection, the privacy of experience, and the extent to which the mind can be understood independently of its social and linguistic environment.