Attributes of Mind
Three attributes of mind stand out: intentionality, subjectivity, and privacy. The mind is essentially about something; the mind is accessible only from a certain point of view; the mind is known directly only by its subject. I take it these attributes are familiar and I won’t elaborate on them (or defend them). Are they independent of each other or are they conceptually connected? Could they be instantiated separately? Is one of them basic? Are there three mind-body problems corresponding to each attribute or is there just one mind-body problem with three different formulations? These questions are by no means easy, because on the face of it the three attributes are differently defined. There is some feeling, I think, that intentionality is basic: subjectivity and privacy are consequences of it. But the conceptual links are obscure partly because intentionality is itself obscure (does anyone know what “intentional inexistence” means or what “directedness” is?). In intentionality a world is presented to a subject, and the upshot is that only someone with that type of presentation can know what it involves, and no one else can have the kind of epistemic access to it that the subject has. Obscurely, intentionality entails subjectivity and privacy (the bat has experiences of things and this determines what it’s like to be a bat and no one else can observe what the bat is experiencing). The mind is outer-directed, inwardly grasped, and not publicly known; and it is because of intentionality that subjectivity and privacy obtain—though the links are not transparent. So at least we are inclined to suppose: the attributes of subjectivity and privacy don’t seem basic relative to intentionality, and it is implausible that the three attributes are unconnected. They come as a package deal not as a mere list. Can we articulate this dependence further?
Perhaps we can find some illumination by considering matter (corporeal things). What are the essential attributes of matter? Matter is extended in space, objective, and public: it has shape and size, can be grasped from many points of view, and can be observed by different perceivers. Are these independent attributes or do they form an intelligible cluster? We know what Descartes would say: extension is the basic defining attribute of matter, with objectivity and publicity consequences of it. Again, the links are not totally transparent, but they are intuitively compelling: extension in space gives rise to objectivity (i.e. objects in space can be grasped from many perceptual points of view), and what is extended in space can be perceived by the senses. So we can simplify and say that the essential attribute of matter is extension, with objectivity and publicity as derivative (though introducing various epistemic considerations). Hence it has been common to describe matter as extended substance: it is the form that reality (“substance”) takes when it is what we call “physical”. By analogy, we can say that the essential attribute of mind is intentionality, with subjectivity and privacy as derivative. It is the form that reality (“substance”) takes when it is what we describe as “mental”. These are necessary truths of the metaphysics of matter and mind. Matter is reality extended in space and having spatial relations to other matter; mind is reality pointing beyond itself and not standing in spatial relations to other things (intentionality doesn’t even require the existence of what it “points” to). Matter exists by virtue of having extension; mind exists by virtue of having intention (if I may put it so). Matter lacks intentionality (it doesn’t intend anything); mind lacks extension (it doesn’t occupy space with a specific shape and size). These are two forms that reality may take—two “modes of being” that reality may assume. There are extensional facts and intentional facts.
We can now pose the following question: Why does reality (existing stuff) take these two forms? In the case of matter the only answer can be that this is what matter is: if you are going to have matter, you are going to need extension (God had no choice in the matter of matter). The big bang supposedly created matter and space (they are coeval), so it had no choice about how matter would exist, i.e. by means of extension. But in the case of mind extension will not suffice: extended things don’t have intentionality, not in virtue of extension anyway. So if mind is to exist reality must be capable of intentionality. How is it so capable? Here is a hypothesis: intentionality is the form that reality takes when it is not physical. As a matter of metaphysics, reality can either be extended (hence material) or it can be intentional (hence mental). Since mind lacks extension, it can only exist by being intentional (in the technical sense), because there is no other way for reality to exist. We might try to imagine many ways reality could exist—many “modes of being”—but in fact there are just two: by extension or by intention. Both are basic forms that reality may assume. Before the big bang there was no extension (no matter in space), but there could have been intention (a sort of primitive “directedness”). Indeed, we can envisage a kind of quasi-mental sea of intentionality existing prior to the emergence of extended stuff. A Brentano-style panpsychist will suppose that the basic mental nature of the universe is actually constituted by intentionality (or “proto-intentionality”). The point I am making is that both extension and intention are ways that things might primitively be. Intention doesn’t derive from extension (it couldn’t) but instead is just how reality is constituted when it isn’t material. Thus the falsity of materialism is the reason mind is intentional: it leaves the mind with no choice about how to be—because if you are not material you must be intentional (likewise if you are not intentional you must be material). That, at any rate, is the hypothesis: the inescapable dualism (not pluralism!) of the cosmos—the necessity to be either extended or intended (so to speak). We might even speculate that the default condition of the universe is intentionality, with extension introduced later into the picture by way of the big bang. Matter came late to the party, invited in by the big bang’s obsession with extension in space; before that the universe was a hotbed of intentionality (or some primitive antecedent of what we know today by that name). Matter (extended substance) is the anomaly, the parvenu, the new kid on the block; mind in the form of intentionality is the normal way reality comports itself—the old money, the ancient customs, the way things are traditionally done. If there is going to be immaterial substance (and before the big bang that’s all there was, matter requiring spatial extension), there is no choice but to go with intentionality—there being no other way that reality can be. Extension and intention exhaust the options, according to the hypothesis (and really what else could reality be?). Descartes supposed that the essence of mind is thought; that was too narrow and Brentano’s intentionality is its more inclusive heir: but he never contemplated any third possibility—something other than thought or extension. There is just no third option, as a matter of metaphysical necessity: to be is to be either extended on intended—spread out in space or directed beyond itself. Everything material has extension and everything mental has intention, and there is nothing but the material and the mental. What we call the mind is reality in its non-extended mode just as what we call matter is reality in its non-intended mode. Intention then gives rise to subjectivity and privacy, as extension gives rise to objectivity and publicity. That is how the universe is basically organized.
Of course, all this is deeply mysterious. Why did the universe decide to give birth to extended stuff late in its lifecycle? How did it pull off that trick? What does it mean to “occupy” space? And what exactly is the alleged primitive intentionality (we have enough trouble understanding the sophisticated kind we encounter in ourselves every day)? Does it allow for directedness towards the non-existent? Might it be that both sorts of reality derive from some yet more basic stuff of which they are both aspects? Is some sort of idealism indicated? How can an organism harbor both sorts of reality given that organisms are extended substances with intentional properties? By rights such a thing ought to be impossible, since extension can’t give rise to intention. Can we avoid dualism? Are our concepts hopelessly inadequate for doing advanced cosmology? Even if the hypothesis of a dual reality is correct, how could it be established? What does seem clear is that intentionality, as understood (sic) by Brentano, doesn’t fit into a world of extended bodies in space standing in spatial relations; that is precisely what the mind is not according to Brentano’s thesis. All we know is that we have two types of being here—two ways reality can configure itself. These appear irreducibly distinct—yet curiously conjoined. Presumably the brain is more than an extended thing, given that it powers the mind, but nothing visible in the brain suggests what this more amounts to. We can report, I think, that mind is more complex than matter in the sense that intentionality is a more complex phenomenon than extension: mere extension is simpler than the kind of directedness Brentano had in mind, especially in relation to non-existence. Intentionality has more internal structure, more design; extension is “dumber” than intention. Not that extension is as simple as a mathematical point; after all, it exhibits all the complexity of geometry. But it is grosser than intention, less articulated. Intention needs a subject and an Object and a “relation” of apperception (whatever that may be). If this structure characterizes much of reality (“pan-intentionalism”), then reality is more articulated than the simple extension model suggests. A human preference for simplicity therefore militates against the idea. Geometry is not adequate to capture it. Our worldview tends to be dominated by our senses, but these are geared to representing extended things in space; a completely different way of thinking is needed to conceptualize intentionality. We possess such a way in the form of introspection, but it is hard to integrate this with the perceptual viewpoint (without introspection we would probably never have thought of intentionality). Russell would say we are acquainted with the underlying intentional structure of the world in acts of introspection, but perception yields nothing of this sort, only extended objects in space. We tend to think that the objects of perception are basic and primary, but this bias clashes with the facts of introspection. Ideally we should be open to both sorts of reality (Berkeley had a lot of trouble with the very concept of matter). True, there are puzzles aplenty, but that (as they say) is the mark of a fruitful research program. The concepts of intentionality and extension are the fundamental concepts in their respective domains, and they form the twin pillars of a realistic cosmology.
 It might be tempting to suppose that mind could exist in a non-intentional form, as a kind pure subjectivity—a pre-intentional consciousness. Thus we have William James’s famous phrase “a blooming buzzing confusion” used to characterize the mind of the infant before real thought steps in. But such an idea tacitly brings in intentionality because blooming and buzzing are states of mind in which things outside seem a certain way—as with flowers and bees. Whenever there is consciousness there is some kind of outer-directedness no matter how vague or general or inarticulate. Mind requires intentionality—as matter requires extensionality.
 I need to say a word about mathematics, a big subject in the present context. It might be said that mathematical existence is a third type of reality distinct from material extension and mental intention. I don’t necessarily disagree, but mathematical reality isn’t going to cut it as the essence of the mental: it is too abstract and unchanging. Empirical reality has only two ways to be; mathematics can happily exist in its separate sphere. Of course, one might try to reduce mathematics to matter or mind (nominalism or psychologism), thereby keeping things down to two basic categories; but even if we resist such reductions and stick to Platonism, mathematics doesn’t make room for a third category of non-abstract reality. Concrete reality is (according to our hypothesis) necessarily limited to the two categories of the extended and the intended (matter and thought, roughly).
 I would say that despite the huge influence of Brentano’s concept of intentionality (one of the great discoveries of philosophy) it has never been fully integrated into the subject. True, it shaped phenomenology (and existentialism), and is often cited in works of analytic philosophy, but it has never formed the foundation of a systematic metaphysics. Nor has it received the analytical attention that has been lavished on the notion of linguistic reference (its spoken analogue). One searches in vain for any incorporation of it into the works of Russell and Wittgenstein, as well as other luminaries. Partly this may have to do with Brentano’s less than lucid style (though it isn’t that bad), but more likely it results from the internal obscurity of the notion: for it is hard to know what exactly we are dealing with here. Linguistic reference gives the impression (probably illusory) that we know what we are talking about, but words like “directedness” and “intentional inexistence” are not calculated to promote confidence that we have hold of a real phenomenon. Nevertheless, the intuitive power of the notion has ensured its continued presence on the philosophical scene. For my part, I’d like to see it play a more prominent role in analytical philosophy of mind and in metaphysics.