The Idea

Intentionality is the aboutness of mental states. Your belief is about something, your desire is for something, your perception is of something. Brentano called it the mark of the mental: the thing that distinguishes minds from mere physical happenings. The directedness survives even when the target does not exist (fear of ghosts, belief in unicorns), and two thoughts can differ while pointing at the same object (“the morning star” and “the evening star” both pick out Venus).

The hard question underneath: what makes a thought about X rather than Y, and how does a physical system come to have aboutness at all? The candidate answers each break somewhere. Causal theories struggle with misrepresentation, resemblance theories with abstract objects, functional-role theories with holism, teleological theories with what grounds “proper” function. None has won.

Why I Keep It

It frames my representation questions. Do bilingual speakers hold the same content under different linguistic labels, or different contents? What does translation actually have to preserve? And for computational models: what would make a model’s internal state about something, rather than merely correlated with it?

Tensions

• Original versus derived intentionality: if maps and words only borrow aboutness from minds, what would a machine need for the genuine article?
• Narrow versus wide content: does what your thought is about depend on what is in your head, or partly on the world you happen to be in?

Key Sources

• Brentano, F. (1874). Psychology from an Empirical Standpoint
• Searle, J. (1983). Intentionality: An Essay in the Philosophy of Mind
• Dennett, D. (1987). The Intentional Stance