1 Historical Development
1.1 Scholastic Origins
The concept of intentionality originates in medieval Scholastic philosophy, particularly in the works of Thomas Aquinas and Duns Scotus. The term derives from the Latin *intentio*, meaning a "stretching toward" or "directedness". Scholastic thinkers used *esse intentionale* (intentional being) to describe how the mind apprehends objects: a mental act contains the form of the object without its matter. For instance, when perceiving a tree, the mind holds an "intentional species" of the tree, allowing the object to be present in thought. This notion distinguished the mind's mode of being from the physical existence of things and laid the groundwork for later theories of mental representation.
1.2 Brentano and the Revival of Intentionality
Franz Brentano reintroduced intentionality to modern philosophy in his 1874 work *Psychology from an Empirical Standpoint*. He argued that intentionality is the defining characteristic of mental phenomena—every mental act is directed toward an object. For Brentano, this directedness is not merely a relation to an external thing but a feature inherent in the act itself.
1.2.1 Intentional Inexistence
Brentano coined the term "intentional inexistence" to describe the mode of being of the object of thought as it exists within the mental act. An object need not exist in reality; it can be entirely imaginary or even contradictory (e.g., a golden mountain or a round square). The "inexistence" means that the object is present *in* the mind as an intentional correlate, regardless of its actual existence. This property raised foundational questions about how minds can relate to non-existent entities.
1.2.2 The Priority of the Mental
Brentano held that all mental phenomena are intentional, and that physical phenomena (such as colors or sounds) lack this directedness. He used this criterion to demarcate psychology from natural science. For him, intentionality provides a clear boundary: any phenomenon that exhibits aboutness is mental, whereas purely physical events are not. This thesis became known as "the mark of the mental" and shaped subsequent debates about the nature of consciousness and cognition.
1.3 Husserlian Phenomenology
Edmund Husserl, a student of Brentano, developed intentionality into a central pillar of phenomenology. He sought to describe the structures of conscious experience without presupposing the existence of an external world. For Husserl, intentionality is not merely a property of individual mental states but a fundamental structure of consciousness itself.
1.3.1 Noema and Noesis
Husserl introduced a distinction between *noesis* (the act of intending) and *noema* (the intentional content or object-as-intended). The noema is the meaning through which an object is given to consciousness, not the object itself. For example, seeing a house involves a noetic act of perception and a noematic sense that includes the house's appearance, its spatial orientation, and its significance. This analysis allowed Husserl to account for variations in how the same object can be intended differently (e.g., seen, remembered, or imagined).
1.3.2 The Transcendental Ego
Husserl argued that intentional acts are unified by a transcendental ego—a pure subject of experience that constitutes the meaning of objects. By performing the "phenomenological reduction" (bracketing the natural attitude), one can examine how the ego actively structures intentional experiences. This idealist turn moves beyond Brentano’s empirical psychology, positing that the world’s objectivity is itself a product of transcendental subjectivity.
1.4 Analytic Philosophy
In the 20th century, analytic philosophers engaged with intentionality from the perspectives of logic, language, and natural science. Their approach often sought to clarify the concept through formal analysis and to determine whether it could be reconciled with a physicalist worldview.
1.4.1 Quine and the Rejection of Intentionality
Willard Van Orman Quine famously criticized intentionality as scientifically intractable. In "Word and Object" (1960), he argued that intentional idioms (e.g., "believes that...") resist straightforward translation into extensional language and lack clear individuation conditions. Quine advocated for "semantic ascent" away from mentalistic talk and toward behavioral evidence, effectively dismissing intentionality as a legitimate subject for scientific inquiry. His stance influenced eliminative materialism, which sought to replace folk-psychological concepts with neuroscientific ones.
1.4.2 Searle's Biological Naturalism
John Searle defended intentionality as a real, biologically grounded phenomenon. In *Intentionality* (1983), he argued that mental states are caused by brain processes and are themselves features of the brain. Intentionality, for Searle, is a natural property like digestion or photosynthesis, not something that requires reduction to non-intentional terms. He introduced the notion of the "Background"—a set of non-intentional capacities that enable intentional states to function. Searle’s position attempts to preserve the commonsense reality of mental directedness while remaining consistent with a scientific worldview.
2 Core Philosophical Issues
2.1 The Nature of Intentional Content
Intentional content is what a mental state is about—the specific object or state of affairs it represents. Philosophers debate the structure and format of this content.
2.1.1 Propositional Content vs. Non-Propositional Content
Most intentional states (e.g., beliefs, desires) have propositional content: they are directed toward a proposition, such as "that it is raining". Propositions are abstract entities that can be true or false. However, some mental states—like loving a person or imagining a scene—may have non-propositional content, where the object is presented directly without a propositional structure. The debate concerns whether all intentionality can be reduced to propositional attitudes or whether there are genuine cases of object-directed intentionality that resist such analysis.
2.1.2 Intensionality vs. Intentionality
"Intentionality" (with a 't') refers to the aboutness of mental states, while "intensionality" (with an 's') is a linguistic property of contexts that fail to preserve truth under substitution of co-referring terms (e.g., in "believes that" clauses). The two are often conflated because intentional states typically exhibit intensionality: one can believe that Hesperus is bright without believing that Phosphorus is bright, even though both refer to Venus. However, not all intensional contexts are mental (e.g., modal contexts), and some theorists argue that intensionality is merely a symptom of intentionality, not its essence.
2.2 Directedness and Objectivity
Intentionality seems to involve a relation between a mental state and an object, but this raises puzzles when the object does not exist.
2.2.1 Intentionality Toward Nonexistent Objects
One can think about unicorns, Hamlet, or a square circle even though these entities do not exist. How can a mental state be directed at something that is not there? Brentano's intentional inexistence offered one solution: the object exists intentionally within the act. Others, like Alexius Meinong, posited a realm of non-existent objects. A more common contemporary approach is to analyze such states as involving propositional contents that are false or empty: "I believe that there are unicorns" is a belief with a false proposition, not a relation to a unicorn.
2.2.2 The Problem of Misrepresentation
If a mental state represents an object, how can it misrepresent it? For example, perceiving a stick in water as bent involves an error. Misrepresentation challenges causal theories of content, because the cause of a belief (the straight stick) differs from the content (bent stick). Solving misrepresentation requires explaining how mental states can have correctness conditions that are sometimes unsatisfied, which is crucial for a robust theory of intentional content.
2.3 The Mark of the Mental
Brentano's claim that intentionality is the distinctive feature of the mental remains influential but contested.
2.3.1 Brentano's Thesis
The thesis holds that all and only mental phenomena are intentional. Proponents argue that even sensations like pain have intentional content (pain is "about" a bodily disturbance). If correct, it provides a clear criterion for demarcating the mental from the physical, supporting a non-reductive view of mind.
2.3.2 Counterexamples and Challenges
Critics point to phenomena that are mental but apparently non-intentional: moods (e.g., free-floating anxiety with no specific object), bodily sensations (pure pain without location), or states of consciousness (raw feels). Others argue that some physical systems (e.g., thermostats) exhibit a kind of directedness, undermining the uniqueness claim. Defenders respond that such cases either have implicit intentionality or are mischaracterized. The debate continues across philosophy of mind and cognitive science.
3 Types of Intentional States
3.1 Belief and Desire
Beliefs and desires are paradigmatic intentional states, often jointly explaining action.
3.1.1 Direction of Fit
Beliefs purport to represent how the world is; they have a "mind-to-world" direction of fit: a belief is true if it matches the world, false otherwise. Desires, by contrast, specify how the world ought to be; they have a "world-to-mind" direction of fit: a desire is satisfied if the world changes to match it. This distinction is central to understanding the functional roles of different intentional states.
3.1.2 World-to-Mind vs. Mind-to-World
The two directions of fit are sometimes illustrated by a shopping list analogy. A grocery list used as a record (belief-like) tracks what has been bought; if the list and cart disagree, the list is wrong. A list used as a plan (desire-like) guides purchases; if list and cart disagree, the cart is wrong. Many states, such as intentions, combine both directions: they represent a future state of affairs to be realized through action.
3.2 Perception and Action
Intentionality is not limited to abstract cognition; it permeates sensory experience and motor behavior.
3.2.1 Perceptual Intentionality
Perceptual experiences are intentionally directed toward objects and properties in the environment. When one sees a red apple, the experience is "about" that apple and its redness. Unlike belief, perception is often vivid and presentational, offering the object as directly given. Philosophers debate whether perceptual content is conceptual (requiring concepts like "apple") or non-conceptual (raw sensory input).
3.2.2 Intention in Action (Practical Intentionality)
Intentions are a distinct type of mental state that guide action. An intention to raise one's arm has both a representational component (representing the goal) and a conative component (driving the movement). Some theorists, like Michael Bratman, distinguish between prior intentions (formed in advance) and intentions-in-action (the ongoing guidance of behavior). This practical intentionality bridges the gap between thought and bodily movement.
3.3 Memory and Imagination
Memory and imagination involve directedness toward times and possibilities beyond the immediate present.
3.3.1 Episodic and Semantic Memory
Episodic memory is intentional about past personal experiences (e.g., remembering one's first day at school), while semantic memory is about facts (e.g., knowing Paris is the capital of France). Both involve intentional content, but episodic memory typically includes a sense of "re-experiencing" the past event. Philosophical issues include whether memory preserves original perceptual content or reconstructs it.
3.3.2 Imagining as Intentional
Imagination allows the mind to represent scenarios that are not real—fictional worlds, hypothetical situations, or future possibilities. Imagining a unicorn is intentionally directed at a unicorn-like entity, even though none exists. Imagination often involves mental imagery but can also be propositional (imagining that something is the case). Its intentional structure is similar to perception but without a commitment to existence, making it a fertile area for exploring intentionality toward nonexistents.
4 Intentionality in Contemporary Debates
4.1 Naturalizing Intentionality
A central project in philosophy of mind is to explain intentionality within a naturalistic framework—that is, in terms of non-intentional, physical processes. Several competing theories have been proposed.
4.1.1 Causal Theories (Dretske, Fodor)
Fred Dretske and Jerry Fodor developed causal theories of content. A mental state (e.g., a belief that there is a cow) means "cow" because it is reliably caused by cows under normal conditions. Fodor's "asymmetric dependence" theory tries to handle misrepresentation: a false cow-belief caused by a horse depends asymmetrically on the genuine cow-belief. Causal theories face difficulties with abstract concepts and systematic misrepresentation.
4.1.2 Teleosemantics (Millikan, Papineau)
Ruth Millikan and David Papineau propose teleosemantics, which grounds intentional content in biological function. A mental state represents what it is its evolutionary function to indicate. For example, a frog's visual system is designed to detect flies; its "fly-detecting" state represents fly even if it fires at a small moving black dot. Teleosemantics accounts for norms (correct representation) but struggles with novel concepts and cultural learning.
4.1.3 Interpretivism (Dennett)
Daniel Dennett's interpretivism avoids reducing intentionality to brain states. Instead, the "intentional stance" is a strategy for predicting behavior by attributing beliefs and desires. An entity has intentional states only insofar as it is useful to interpret it that way. This view is instrumentalist: intentionality is a useful fiction, not a real property. Critics argue it fails to capture the genuine directedness of mental states.
4.2 Intentionality and Consciousness
The relationship between intentionality and phenomenal consciousness (subjective experience) is a major topic.
4.2.1 The Phenomenal-Intentional Nexus
Some philosophers, like Terence Horgan and John Tienson, argue that all phenomenal states have intentional content and vice versa—the phenomenal-intentional nexus. For them, the "what it's like" of an experience is inseparable from its aboutness. For example, the felt quality of seeing red is partly constituted by how it represents redness. Others, like Ned Block, hold that phenomenal states (e.g., raw feels) can be non-intentional, allowing for a separation.
4.2.2 Cognitive Phenomenology
Does thinking have a distinctive "feel"? Cognitive phenomenology is the thesis that propositional attitudes (judging, doubting, etc.) have a phenomenal character beyond sensory imagery. For instance, the experience of "grasping" a proof or "suddenly understanding" an idea may be a conscious intentional state. Defenders argue that without cognitive phenomenology, conscious thought would be indistinguishable from unconscious thought; skeptics claim that all cognitive phenomenology reduces to sensory or emotional phenomenology.
4.3 Social and Linguistic Intentionality
Intentionality extends beyond individual minds to groups and to language.
4.3.1 Collective Intentionality (Searle, Gilbert)
How can groups have intentions? John Searle argues that collective intentionality is a primitive form of "we-intentionality"—a single mind cannot have it alone, but individuals can participate in shared intentions. Margaret Gilbert proposes that joint commitment creates a "plural subject" with its own intentions. Collective intentionality is crucial for understanding social institutions, cooperation, and shared cultural practices.
4.3.2 Intentionality of Language and Meaning
Linguistic expressions acquire meaning through their connection to mental intentionality.
4.3.2.1 Gricean Meaning
H.P. Grice analyzed speaker meaning in terms of communicative intentions: a speaker *means* something by an utterance if they intend to produce a belief in the audience by means of the audience's recognition of that intention. This reduces linguistic meaning to complex intentional states, grounding semantics in psychology. Critics question whether all meaning can be explained via such iterative intentions, especially for conventional or non-literal language.
4.3.2.2 Speech Acts and Illocutionary Force
John Austin and John Searle developed speech act theory, distinguishing the *locutionary* (literal meaning), *illocutionary* (the act performed in saying, e.g., promising), and *perlocutionary* (the effect on the hearer). Illocutionary acts require specific intentional states: a promise expresses an intention to do something, an assertion expresses a belief. The intentionality of speech acts bridges mind and language, showing how speakers use words to perform actions based on their mental directedness.