Philosophical Investigations — Ludwig Wittgenstein

The book opens with Augustine’s description of learning language: adults point to things, children associate sounds with objects, and words become names. Wittgenstein treats this as a powerful but misleading picture. It works for some nouns in some contexts, but it cannot explain orders, questions, jokes, numbers, colours, pain, games, or the many other things language does. The danger is not that naming never happens, but that one simple case becomes a model for all meaning.

Ostensive definition looks simple: point and say a word. But pointing at a pencil could mean pencil, wood, one, this colour, this shape, or writing tool, depending on what the learner is prepared to do with the sign. A gesture only teaches within a background practice. This undermines the thought that language rests on bare acts of attaching names to objects. > An ostensive definition can be variously interpreted in every case.