Book: Wittgenstein on Rules and Private Language

Overview
Saul Kripke offers a striking and controversial interpretation of Ludwig Wittgenstein's investigations into meaning, rule-following, and private language. The account reframes Wittgenstein's remarks as posing a skeptical paradox: given any finite history of a subject's linguistic behavior, an infinite number of different rules could be said to accord with that history, so nothing in the subject's past use uniquely determines which rule is correct. This line of thought sets up a challenge to the idea that meanings are grounded in individual mental facts.
Kripke's interpretation, often nicknamed "Kripkenstein," emphasizes the apparent gap between individual psychology and the normative notion of correctness that language requires. Rather than offering a simple reconstruction, the argument is staged as a dialectic that brings out the tension between private mental states and public criteria for meaning.

The rule-following paradox
The paradox is illustrated by the "rule-following" problem: any finite set of performed actions is consistent with many possible rules for extending that behavior. Kripke uses a vivid example of a function that matches ordinary addition on all previously encountered cases yet diverges on future ones; this shows how past performance underdetermines future application. The skeptic concludes that there is no fact about the agent that settles which rule they meant to follow.
This skeptical formulation reframes Wittgenstein's point that correctness in following a rule cannot be grounded solely in individual, inaccessible mental states. If meaning were fixed by such states, the normativity of correctness and incorrectness would be unintelligible, since there would be no criterion to distinguish one continuation from another.

Private language and social criteria
Kripke connects the rule-following paradox to the private language argument: a language that refers only to a subject's inner, private sensations lacks public criteria for correctness and so cannot sustain meaningful rule-guided use. The idea is that linguistic norms require external standards; without them talk of "what someone meant" becomes vacuous because meaning is not a private object but something manifested in a pattern of communal practice.
On this reading, the remedy to skepticism is not to look inward for a fact that fixes meaning but to acknowledge the role of shared practices and institutions. Correct application of words depends on communal agreement, training, and the social enforcement of norms rather than on an infallible inward standard.

Responses and proposed solutions
Kripke lays out and evaluates several possible responses to the skeptic. One "straight" solution would posit inner facts, dispositions or psychological states, that determine meaning, but Kripke argues these fail to meet the skeptic's demands. Another family of replies appeals to normative practices: the community's ability to criticize, teach, and correct supplies the needed criteria. Kripke himself advances a "skeptical solution" that accepts the skeptic's thrust while dissolving its force by showing that ordinary language practices and normative judgments remain intact even if no metaphysical fact pins down meanings.
This solution is paradoxical: it concedes that nothing in the subject's private history determines correct future applications, yet insists that our ordinary language game and the social nature of rule-following are sufficient to underwrite meaning and normativity.

Impact and continuing debate
Kripke's reading energized a large literature and intense debate among philosophers of language, mind, and Wittgenstein scholars. Supporters find in the skeptical framing a powerful illumination of Wittgenstein's central concerns about normativity and communal grounding. Critics argue that Kripke misreads Wittgenstein, overstates the paradox, or unduly privileges skeptical rhetoric over therapeutic dissolution.
Whatever stance one takes, the result has been a sustained inquiry into how rules, meanings, and mental states are related, and whether normativity ultimately rests on inner facts, external practices, or some distinctive interplay between the two. The discussion continues to shape contemporary accounts of linguistic meaning, mental content, and the social foundations of understanding.