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." 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.
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. • 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. 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).
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.
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.
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." == Objections and replies ==