The first group of selections complete the private language argument and the remainder begin the discussion of a related issue, the "problem of other minds": if, as Descartes says in the second of his Meditations, we must judge that the people passing before us have minds and are not simply automatons (as Descartes held that animals were), how can we support this judgment? In §§281-315, Wittgenstein attempts to dissolve this problem and also situates himself with respect to the behaviorist program in psychology.

§§270-280. The inner object drops out. If we imagine a genuine use for a sign that we might take to denote a private sensation, the correct identification of the sensation becomes irrelevant so long as our use of the sign is in accord with public criteria (§270). If we took the identity of the sensation to be significant, we would pretend to give meaning to a question that is in principle unanswerable (§272). The sections §§277-279 could be understood as an attempt to explain our readiness to speak of private languages; Wittgenstein traces a wish to distinguish between public and private senses of terms to the differences in our experiences when we attempt to contemplate such senses, a diagnosis that is analogous to those in §§38 and 173. In §280, he applies the considerations of the preceding sections to reject the idea of private information, an issue that will turn up again in §§288ff.

§§281-287. Ascriptions of mental life to others (3rd person). These sections are directed against both dualism (of mind and body) and behaviorism. We know how to ascribe mental life only when there is human-like behavior (§283). But the attitude accompanying such descriptions shows that they are not simply descriptions of behavior (§286). In other works, Wittgenstein rejects both the reaction of the behaviorist (who says, "But surely all we have here is behavior") and the dualist (who says, "But surely there is something more"): to deny that mental ascriptions are descriptions of behavior is not to assert that they are descriptions of something else.

§§288-294. Ascriptions to oneself (1st person). In mental ascriptions to oneself there is no chance of error, but that is not to say that we know some description with certainty. To see things this way is to misunderstand the usual language game (§288 end, and also §292). Our right to make these ascriptions to ourselves needn't lie in a justification for them (§289). Genuine descriptions play a special sort of role in language games; they are not like pictures hanging on a wall (§291).