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.
Overview 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.
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").
Other 20th-century philosophers such as Gilbert Ryle and A. J. Ayer were critical of Husserl's concept of intentionality and his many layers of consciousness. Ryle insisted that perceiving is not a process, and Ayer that describing one's knowledge is not to describe mental processes. The effect of these positions is that consciousness is so fully intentional that the mental act has been emptied of all content, and that the idea of pure consciousness is that it is nothing. (Sartre also referred to "consciousness" as "nothing").
Platonist Roderick Chisholm has revived the Brentano thesis through linguistic analysis, distinguishing two parts to Brentano's concept, the ontological aspect and the psychological aspect. Chisholm's writings have attempted to summarize the suitable and unsuitable criteria of the concept since the Scholastics, arriving at a criterion of intentionality identified by the two aspects of Brentano's thesis and defined by the logical properties that distinguish language describing psychological phenomena from language describing non-psychological phenomena. Chisholm's criteria for the intentional use of sentences are: existence independence, truth-value indifference, and referential opacity.
In current artificial intelligence and philosophy of mind, intentionality is sometimes linked with questions of semantic inference, with both skeptical and supportive adherents. John Searle argued for this position with the Chinese room thought experiment, according to which no syntactic operations that occurred in a computer would provide it with semantic content. Others are more skeptical of the human ability to make such an assertion, arguing that the kind of intentionality that emerges from self-organizing networks of automata will always be undecidable because it will never be possible to make our subjective introspective experience of intentionality and decision making coincide with our objective observation of the behavior of a self-organizing machine.
The problem of intentional inexistence 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. This is particularly relevant for cases involving objects that have no existence outside the mind, as in the case of mere fantasies or hallucinations.
For example, assume that Mary is thinking about Superman. On the one hand, it seems that this thought is intentional: Mary is thinking about something. On the other hand, Superman does not exist. This suggests that Mary either is not thinking about something or is thinking about something that does not exist (that Superman fiction exists is beside the point). Various theories have been proposed in order to reconcile these conflicting intuitions. These theories can roughly be divided into eliminativism, relationalism, and adverbialism. Eliminativists deny that this kind of problematic mental state is possible. Relationalists try to solve the problem by interpreting intentional states as relations while Adverbialists interpret them as properties.
Eliminativism Eliminativists deny that the example above is possible. It might seem to us and to Mary that she is thinking about something but she is not really thinking at all. Such a position could be motivated by a form of semantic externalism, the view that the meaning of a term, or in this example the content of a thought, is determined by factors external to the subject. If meaning depends on successful reference then failing to refer would result in a lack of meaning. The difficulty for such a position is to explain why it seems to Mary that she is thinking about something and how seeming to think is different from actual thinking.
Relationalism Relationalists hold that having an intentional state involves standing in a relation to the intentional object. This is the most natural position for non-problematic cases. So if Mary perceives a tree, it could be said that a perceptual relation holds between Mary, the subject of this relation, and the tree, the object of this relation. Relations are usually assumed to be existence-entailing: the instance of a relation entails the existence of its relata. This principle rules out that people can bear relations to non-existing entities. One way to solve the problem is to deny this principle and argue for a kind of intentionality exceptionalism: that intentionality is different from all other relations in the sense that this principle does not apply to it.
A more common relationalist solution is to look for existing objects that can play the role that the non-existing object was supposed to play. Such objects are sometimes called "proxies", "traces", or "ersatz objects". It has been suggested that abstract objects or Platonic forms can play this role. Abstract objects have actual existence but they exist outside space and time. So when Mary thinks about Superman, she is standing in a thinking relation to the abstract object or the Platonic form that corresponds to Superman. A similar solution replaces abstract objects with concrete mental objects. In this case, there exists a mental object corresponding to Superman in Mary's mind. As Mary starts to think about Superman, she enters into a relationship with this mental object. One problem for both of these theories is that they seem to mischaracterize the experience of thinking. As Mary is thinking about Superman, she is neither thinking about a Platonic form outside space-time nor about a mental object. Instead, she is thinking about a concrete physical being. A related solution sees possible objects as intentional objects. This involves a commitment to modal realism, for example in the form of the Lewisian model or as envisioned by Takashi Yagisawa.
Adverbialism Adverbialists hold that intentional states are properties of subjects. So no independent objects are needed besides the subject, which is how adverbialists avoid the problem of non-existence. This approach has been termed "adverbialism" since the object of the intentional state is seen as a modification of this state, which can be linguistically expressed through adverbs. Instead of saying that Mary is thinking about Superman, it would be more precise, according to adverbialists, to say that Mary is thinking in a superman-ly manner or that Mary is thinking superman-ly. Adverbialism has been challenged on the grounds that it puts a strain on natural language and the metaphysical insights encoded in it. Another objection is that, by treating intentional objects as mere modifications of intentional states, adverbialism loses the power to distinguish between different complex intentional contents, the so-called many-property-problem. Dennett's taxonomy of current theories about intentionality Daniel Dennett offers a taxonomy of the current theories about intentionality in Chapter 10 of his book The Intentional Stance. Most, if not all, current theories on intentionality accept Brentano's thesis of the irreducibility of intentional idiom. From this thesis the following positions emerge: intentional idiom is problematic for science; intentional idiom is not problematic for science, which is divided into: Eliminative materialism; Epistemological realism; Quinean double standard (see below) which is divided into: adherence to Normative Principle (epistemology), which is divided into: who makes an Assumption of Rationality; who follows the Principle of Charity; adherence to Projective Principle.
Roderick Chisholm (1956), G.E.M. Anscombe (1957), Peter Geach (1957), and Charles Taylor (1964) all adhere to the former position, namely that intentional idiom is problematic and cannot be integrated with the natural sciences. Members of this category also maintain realism in regard to intentional objects, which may imply some kind of dualism (though this is debatable).
The latter position, which maintains the unity of intentionality with the natural sciences, is further divided into three standpoints: Eliminative materialism, supported by W.V. Quine (1960) and Churchland (1981);