Aboutness: the directedness of the mind
When you believe that it is raining, your belief is about the rain. When you want a coffee, your desire is directed at the coffee. This being-about or being-directed-at is what philosophers call intentionality. The word does not mean doing something on purpose; it comes from a Latin root meaning to aim or to point. Beliefs, desires, hopes, fears, and perceptions all have this feature: they reach beyond themselves toward objects, properties, and states of affairs.
A striking wrinkle is that the objects of thought need not exist. You can think about Sherlock Holmes, dread a disaster that never comes, or search for the fountain of youth. Mental states can be directed at things that are absent, fictional, or impossible. Explaining how a state can be about something that is not there is one of the classic puzzles of the mind.
Brentano and the mark of the mental
The concept was reintroduced into modern philosophy by the Austrian philosopher Franz Brentano in 1874. Drawing on medieval scholastic vocabulary, Brentano held that every mental phenomenon is characterized by what he called the intentional inexistence of an object, and that this directedness is the mark of the mental: physical things lack it, mental things always have it. This claim, sometimes called Brentano's thesis, shaped much twentieth-century philosophy of mind, and his student Edmund Husserl made intentionality the cornerstone of phenomenology.
The deep difficulty is naturalizing intentionality: how can a merely physical thing, a lump of neurons, be about anything at all? A rock is not about the rock next to it. Philosophers such as Fred Dretske, Jerry Fodor, and Ruth Millikan have tried to ground aboutness in causal or biological relations, for example in what a brain state reliably tracks or what it was selected to do.
The debate, and what it means for AI
Intentionality sits at the heart of a sharp disagreement about machines. John Searle distinguishes original intentionality, the genuine aboutness of a mind, from derived intentionality, the borrowed meaning of words on a page or symbols in a computer, which are about things only because we interpret them so. On Searle's view a program manipulating symbols has no original intentionality of its own.
Daniel Dennett rejects that split. On his intentional stance, treating a system as if it has beliefs and desires is just a strategy that works when it helps us predict behavior, and there is no deeper fact of intrinsic aboutness to be missing. This dispute has become urgent with large language models: when a system produces fluent language about the world, is it really about anything, or only about it in the derived sense that a book is? Intentionality is the concept on which that question turns.