Through the works of Husserl, who took it over from Brentano, the concept of intentionality received more widespread attention in current philosophy, both continental and analytic. French philosopher Jean-Paul Sartre, in Being and Nothingness, identified intentionality with consciousness, stating that they were indistinguishable from one another, a position that was a stark contrast to Brentano's position that intentionality is but one quality of mental phenomena. German philosopher Martin Heidegger, in Being and Time, defined intentionality as "care" (Sorge), a sentient condition where an individual's existentiality, facticity, and forfeiture to the world identifies their ontological significance, in contrast to that which is the mere ontic (thinghood).
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 a controversial subject and sometimes claimed to be something that a machine will never achieve. 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. As he noted in the article, Searle's view was a minority position in artificial intelligence and philosophy of mind.
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:
Chisholm (1956), Anscombe (1957), Geach (1957), and 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:
Proponents of the eliminative materialism, understand intentional idiom, such as "belief", "desire", and the like, to be replaceable either with behavioristic language (e.g. Quine) or with the language of neuroscience (e.g. Churchland).
Holders of realism argue, in contrast to those in support of C, that there is a deeper fact of the matter to both translation and belief attribution. In other words, manuals for translating one language into another cannot be set up in different yet behaviorally identical ways and ontologically there are intentional objects. Famously, Fodor has attempted to ground such realist claims about intentionality in a language of thought. Dennett comments on this issue, Fodor "attempt[s] to make these irreducible realities acceptable to the physical sciences by grounding them (somehow) in the 'syntax' of a system of physically realized mental representations" (Dennett 1987, 345).
Those who adhere to the so-called Quinean double standard (namely that ontologically there is nothing intentional, but that the language of intentionality is indispensable), accept Quine's thesis of the indeterminacy of radical translation and its implications, while the other positions so far mentioned do not. As Quine puts it, indeterminacy of radical translation is the thesis that "manuals for translating one language into another can be set up in divergent ways, all compatible with the totality of speech dispositions, yet incompatible with one another" (Quine 1960, 27). Quine (1960) and Wilfrid Sellars (1958) both comment on this intermediary position. One such implication would be that there is, in principle, no deeper fact of the matter that could settle two interpretative strategies on what belief to attribute to a physical system. In other words, the behavior (including speech dispositions) of any physical system, in theory, could be interpreted by two different predictive strategies and both would be equally warranted in their belief attribution. This category can be seen to be a medial position between the realists and the eliminativists since it attempts to blend attributes of both into a theory of intentionality. Dennett, for example, argues in "True Believers" (1981) that intentional idiom (or "folk psychology") is a predictive strategy and if such a strategy successfully and voluminously predicts the actions of a physical system, then that physical system can be said to have those beliefs attributed to it. Dennett calls this predictive strategy the intentional stance.
They are further divided into two thesis:
Advocates of the former, the Normative Principle, argue that attributions of intentional idioms to physical systems should be the propositional attitudes that the physical system ought to have in those circumstances (Dennett 1987, 342). However, exponents of this view are still further divided into those who make an Assumption of Rationality and those who adhere to the Principle of Charity. Dennett (1969, 1971, 1975), Cherniak (1981, 1986), and the late Putnam (1983) recommend the Assumption of Rationality, which unsurprisingly assumes that the physical system in question is rational. Donald Davidson (1967, 1973, 1974, 1985) and Lewis (1974) defend the Principle of Charity.
The latter is advocated by Grandy (1973) and Stich (1980, 1981, 1983, 1984), who maintain that attributions of intentional idioms to any physical system (e.g. humans, artifacts, non-human animals, etc.) should be the propositional attitude (e.g. "belief", "desire", etc.) that one would suppose one would have in the same circumstances (Dennett 1987, 343).
Working on the intentionality of vision, belief, and knowledge, Pierre Le Morvan (2005) has distinguished between three basic kinds of intentionality that he dubs "transparent," "translucent," and "opaque" respectively. The three-fold distinction may be explained as follows. Let's call the "intendum" what an intentional state is about, and the "intender" the subject who is in the intentional state. An intentional state is transparent if it satisfies the following two conditions: (i) it is genuinely relational in that it entails the existence of not just the intender but the intendum as well, and (ii) substitutivity of identicals applies to the intendum (i.e. if the intentional state is about a, and a = b, then the intentional state is about b as well). An intentional state is translucent if it satisfies (i) but not (ii). An intentional state is opaque if it satisfies neither (i) nor (ii).