What Is Intentionality?

Direct Answer

Intentionality is the feature of mental states by which they are about, or directed at, things. A belief that it will rain is about rain; a desire for coffee is for coffee; a perception of a tree is of a tree; a fear of heights is of heights. Mental states are not self-contained: they point beyond themselves to objects, properties, and states of affairs. This aboutness or directedness is intentionality.

The word derives from the Latin intendere, "to point toward," and was given its modern philosophical use by the Austrian philosopher Franz Brentano, who argued in Psychology from an Empirical Standpoint (1874) that intentionality is "the mark of the mental": every mental phenomenon is directed at an object, while no physical phenomenon is. On this view, what separates mind from matter is precisely that mental states are about things. The concept has three connected but distinguishable uses: intentionality as the directedness of mental states (aboutness), intentionality as the property of mental states having content or meaning, and intentionality in the derived sense of words and pictures being about things (a book is about Napoleon; a map is about the terrain).

The most striking feature of intentional states is their ability to be about what does not exist. You can believe in unicorns, fear the monster under the bed, hope for a cure for a disease that does not yet exist. Medieval philosophers called this "intentional inexistence" — the object of the state exists in the mind, intentionally, without existing in reality. This is not a flaw but a core feature of thought: much of our mental life is concerned with what is absent, possible, feared, or desired. It also generates the puzzle: how can a physical state of a brain be about something that does not exist at all?

Historical Context

The concept has a long prehistory. Aristotle discussed the forms of things entering the mind in perception; the medieval scholastics developed the notion of "intentional species" by which the mind grasps objects; and Thomas Aquinas distinguished the "intentional existence" of things in the mind from their real existence. The early moderns transformed the concept: Descartes treated ideas as representations of things, and Locke and Hume explained thought in terms of ideas and impressions, each with content.

Brentano's nineteenth-century formulation gave intentionality its modern canonical form and its philosophical weight: if intentionality is the mark of the mental, then a purely physicalist account of mind must either explain how physical states can be about things or deny that intentionality is real. Husserl, a student of Brentano, made intentionality the centerpiece of phenomenology: consciousness is always consciousness of something, and the task of phenomenology is to describe the structures of this directedness. In the analytic tradition, Gottlob Frege's distinction between sense and reference, and Bertrand Russell's theories of denoting, addressed how thought and language manage to be about things.

In the twentieth century, the problem of intentionality became central to the philosophy of mind and language. W. V. O. Quine questioned whether talk of meaning and aboutness could be made scientific; Hilary Putnam's twin earth thought experiment suggested that the content of thought depends on the environment as well as the head ("meaning ain't in the head"); John Searle argued that intentionality is an intrinsic biological feature of the mind that cannot be reproduced by formal symbol manipulation; Daniel Dennett argued that intentionality is a useful stance we adopt toward systems, not a deep fact about them.

Key Arguments & Debates

The central debate is whether intentionality can be naturalized — whether aboutness can be explained within a physicalist framework. The leading proposals:

Teleosemantic theories, developed by Ruth Millikan and David Papineau, hold that mental representations have the function of indicating features of the environment, where the function is fixed by evolutionary history: a frog's visual state indicates "fly" because it evolved to guide fly-catching. The objection is that function-based accounts have trouble with error, novel content, and complex, abstract thought.

Causal and informational theories, associated with Fred Dretske and Jerry Fodor, hold that a representation means what reliably causes it: a state means red because red things cause it. Fodor's "asymmetric dependence" theory handles misrepresentation. The objection: causation is ubiquitous and a state is caused by many things, so picking out the right content is difficult.

Interpretationist theories, associated with Dennett and Donald Davidson, hold that a system has intentional states only relative to an interpretive scheme: we attribute beliefs and desires to predict behavior, and a system is intentional in the derived sense. The objection: this makes intentionality observer-relative and seems to leave out what is real about thought.

Searle's objection to computational theories is famous: in the Chinese Room, a symbol-manipulating system instantiates the right computations but has no understanding — syntax, he argues, is not sufficient for semantics. The debate between "original" (intrinsic) intentionality and "derived" intentionality is central: for Searle, our thoughts have intrinsic aboutness; for many others, all intentionality is ultimately a matter of function, use, or interpretation.

Contemporary Relevance

Intentionality is the philosophical concept at the heart of the modern AI debate. Large language models manipulate symbols and produce text that is about things, but whether they have genuine intentionality — whether their states are really about anything — is contested. On the functionalist-informational view, a model trained on text has states that carry information about language and the world, and may have genuine (if impoverished) intentional content. On Searle's view, they are Chinese Rooms: syntax without semantics. The debate is not academic: the moral status, legal responsibility, and reliability of AI systems depend on whether their states are about the world or merely simulate aboutness.

In neuroscience and cognitive science, the notion of mental representation — states that carry information and guide behavior — is pervasive, and naturalistic theories of intentionality aim to make sense of it. And in philosophy more broadly, intentionality connects to the theory of meaning, the theory of truth, and the nature of normativity: what it is for a belief to be true or false depends on what it is about. Whether aboutness can be explained by physics remains one of the deepest open questions in the philosophy of mind.

Related Concepts

• Mental representation: the vehicles of intentional content.
• The Chinese Room argument: Searle's challenge to computational accounts of intentionality.
• The Chinese Nation thought experiment: Block's challenge to behaviorist and functionalist accounts of content.
• The argument from reason: the claim that intentional content cannot be explained mechanistically.
• Qualia: the phenomenal side of experience, distinct from but related to intentional content.

Further Learning

• Stanford Encyclopedia of Philosophy: Intentionality
• Internet Encyclopedia of Philosophy: Intentionality
• Franz Brentano, Psychology from an Empirical Standpoint (1874).
• John Searle, Intentionality: An Essay in the Philosophy of Mind (1983).