Avicenna's Universals and the Priority of Form — Epoche C1
Contemporary metaphysics grapples with the relationship between wholes and their parts, and with the question of whether universals derive their existence from particulars or the reverse. Two pieces of vocabulary are needed before the question can even be put. A particular is a single individual — this rose, that person — which cannot be wholly present in two places at once. A universal is what many particulars may share: redness, humanness, being a rose. And mereology is simply the formal theory of the part-whole relation, from the Greek meros , part. The dominant contemporary framework, developed above all by David Lewis, combines an austere mereology with a deflationary treatment of universals, and it is standardly taken to entail that particulars come first: universals, on this picture, are shadows cast by the individuals that have them. A correction is required at the outset, because the essay as it previously stood attributed to Lewis the thesis that wholes are 'sets of their parts', and Lewis explicitly denies precisely this. In Parts of Classes (1991) he argues that a class is not the mereological fusion of its members — the fusion of a pack of cards is the same object as the fusion of the fifty-two cards' halves, whereas the corresponding classes differ — and he takes the fusion of many objects to be, in his phrase, nothing over and above those objects taken together, a doctrine known as composition as identity. What is true, and what the essay's argument actually needs, is Lewis's treatment of properties: in 'New Work for a Theory of Universals' (1983) he identifies a property with the set of all its instances, actual and merely possible, so that humanness just is the set of all the humans there are or could have been. On that identification the ontological direction is unambiguous. A set depends for its identity on its members, since a set with different members is a different set, whereas an individual does not depend for its identity on any set to which it belongs. Particulars are therefore prior, and universals are constructions out of them. Lewis complicates this by conceding that not all sets of possibilia carve nature at its joints — some properties are 'natural', and he allows that an Armstrong-style theory of immanent universals might earn its keep in explaining which — but even there a universal is wholly located in each of its instances and has no existence apart from them. The presumption behind all of this is far older than Lewis. In the Categories , Aristotle calls individual substances 'primary' precisely on a dependence criterion: everything else is either said of them or present in them, so that if the primary substances did not exist nothing else could. That is the standard result every undergraduate meets, and it fixes the burden of proof for anyone who wants to reverse the order. Avicenna — Ibn Sīnā, the Persian physician and philosopher who died in 1037 and whose Kitāb al-Shifāʾ (The Book of Healing) transmitted a reworked Aristotelianism to Latin Europe under the name Avicenna — accepts far more of Aristotle than a Platonist would, and yet arrives at a position in which form enjoys a priority that Aristotle's dependence criterion does not capture. Understanding how requires his central technical device. The Threefold Distinction Avicenna's key move, made in the fifth treatise of the Ilāhiyyāt (Metaphysics) of the Shifāʾ and in his commentary on Porphyry's Isagoge analysed by Michael Marmura, is to distinguish three ways of considering a māhiyya — a quiddity or essence, literally a 'what-it-is'. His formula, which became famous in the Latin West as equinitas est equinitas tantum , is that horseness is nothing but horseness: considered in itself it is neither one nor many, neither universal nor particular, neither existent in the world nor existent in a mind. Consideration What accompanies the essence Status In itself ( fī nafsihi ) Nothing but its own constituent notes: animality, rationality Indifferent to universality and particularity; not an existing thing In external things ( fī l-aʿyān ) Matter, place, time, quantity, quality — the individuating accidents Particular, one among many In the mind ( fī l-dhihn ) The accident of being predicable of many Universal Three consequences follow, and they matter for the argument. First, universality is an accident of the essence, something that befalls it in the mind and does not belong to it as such — which is why the essay's earlier claim that Avicenna posits universals 'existing independently in the intellect' as the ground of particulars needs restating. Avicenna is not a Platonist. He argues at length in the same treatise against separately subsistent Forms, on the ground that a Form which is one and yet common to many would have to be both indivisible and divided; and he does not say that universals exist outside minds. What is prior, on his account, is not the universal but the essence considered in itself, which is prior to both its universal and its particular states because both are additions to it. Second, and this is where Avicenna departs decisively from Aristotle's dependence order, the priority claimed here is not existential but constitutive. Avicenna's most consequential thesis, and the one for which he is chiefly remembered in metaphysics, is the real distinction between essence and existence: for everything other than the first principle, what a thing is does not include that it is. His argument is short. I can know perfectly well what a triangle is, or what a phoenix is, and still not know whether any exists; if existence were among the constituent notes of the essence, as rationality is among the notes of humanness, that ignorance would be impossible. Existence is therefore something that accrues to an essence rather than something contained in it. The Aristotelian criterion of priority — if the primary substances did not exist nothing else would — measures existential dependence, and Avicenn