Intentionality

Intentionality is the mental ability to refer to or represent something. Sometimes regarded as the mark of the mental, it is found in mental states like perceptions, beliefs or desires. For example, the perception of a tree has intentionality because it represents a tree to the perceiver. A central issue for theories of intentionality has been the problem of intentional inexistence: to determine the ontological status of the entities which are the objects of intentional states.

An early theory of intentionality is associated with Anselm of Canterbury's ontological argument for the existence of God, and with his tenets distinguishing between objects that exist in the understanding and objects that exist in reality. The idea fell out of discussion with the end of the medieval scholastic period, but in recent times was resurrected by empirical psychologist Franz Brentano and later adopted by contemporary phenomenological philosopher Edmund Husserl. Today, intentionality is a live concern among philosophers of mind and language. A common dispute is between naturalism, the view that intentional properties are reducible to natural properties as studied by the natural sciences, and the phenomenal intentionality theory, the view that intentionality is grounded in consciousness.

The concept of intentionality was reintroduced in 19th-century contemporary philosophy by Franz Brentano (a German philosopher and psychologist who is generally regarded as the founder of act psychology, also called intentionalism) in his work Psychology from an Empirical Standpoint (1874). Brentano described intentionality as a characteristic of all acts of consciousness that are thus "psychical" or "mental" phenomena, by which they may be set apart from "physical" or "natural" phenomena.

Every mental phenomenon is characterized by what the Scholastics of the Middle Ages called the intentional (or mental) inexistence of an object, and what we might call, though not wholly unambiguously, reference to a content, direction towards an object (which is not to be understood here as meaning a thing), or immanent objectivity. Every mental phenomenon includes something as object within itself, although they do not all do so in the same way. In presentation something is presented, in judgement something is affirmed or denied, in love loved, in hate hated, in desire desired and so on. This intentional in-existence is characteristic exclusively of mental phenomena. No physical phenomenon exhibits anything like it. We could, therefore, define mental phenomena by saying that they are those phenomena which contain an object intentionally within themselves.

— Franz Brentano, Psychology from an Empirical Standpoint, edited by Linda L. McAlister (London: Routledge, 1995), p. 68.

Brentano coined the expression "intentional inexistence" to indicate the peculiar ontological status of the contents of mental phenomena. According to some interpreters the "in-" of "in-existence" is to be read as locative, i.e. as indicating that "an intended object ... exists in or has in-existence, existing not externally but in the psychological state" (Jacquette 2004, p. 102), while others are more cautious, stating: "It is not clear whether in 1874 this ... was intended to carry any ontological commitment" (Chrudzimski and Smith 2004, p. 205).

A major problem within discourse on intentionality is that participants often fail to make explicit whether or not they use the term to imply concepts such as agency or desire, i.e. whether it involves teleology. Dennett (see below) explicitly invokes teleological concepts in the "intentional stance". However, most philosophers use "intentionality" to mean something with no teleological import. Thus, a thought of a chair can be about a chair without any implication of an intention or even a belief relating to the chair. For philosophers of language, what is meant by intentionality is largely an issue of how symbols can have meaning. This lack of clarity may underpin some of the differences of view indicated below.

To bear out further the diversity of sentiment evoked from the notion of intentionality, Husserl followed on Brentano, and gave the concept of intentionality more widespread attention, both in continental and analytic philosophy. In contrast to Brentano's view, French philosopher Jean-Paul Sartre (Being and Nothingness) identified intentionality with consciousness, stating that the two were indistinguishable. German philosopher Martin Heidegger (Being and Time), defined intentionality as "care" (Sorge), a sentient condition where an individual's existence, facticity, and being in the world identifies their ontological significance, in contrast to that which is merely ontic ("thinghood").