Particulars

3. Bundles of properties

Consider a particular which has several essential properties and several accidental properties. There is room to consider a theory which identifies the particular with the collection of essential properties, and there is room to consider a theory which identifies the particular with the collection of all its properties. On consideration, however, it can be seen that a particular cannot be identified with any collection which includes an accidental property. An accidental property is something which, by definition, the particular could have lacked. But the bundle of properties which includes that accidental property would not have been the bundle that it is if it had not included that property.

Consider, therefore, the theory which identifies a particular with the collection of its essential properties. An objection can be raised if we show that there can be several particulars which share exactly the same essential properties. Certainly Aristotle thought that different members of the same species share the very same essential properties. For Aristotle, therefore, what distinguishes particulars of the same species is not their ‘form’, but the ‘matter’ on which this form is impressed.

Hence if we are to identify a particular with a collection of essential properties, we must suppose that distinct particulars cannot ever share exactly the same essential properties. Each particular must have some property which no other particular could have. This is what is called an individual essence. One way of thinking of an individual essence is by construing it to be an unshareable conjunction of severally-shareable properties as, for example, Leibniz’s monads. An alternative would be to suppose that for each particular there is a simple essential property called a ‘haecceity’ (from Latin, meaning ‘thisness’) which that particular alone possesses and which nothing else could have had either instead of or as well as it. This notion was articulated by the Islamic philosopher Avicenna (see Ibn Sina §4), and was taken up by some of the scholastic philosophers in Europe, such as Duns Scotus in the thirteenth century, but has been roundly denounced by many since that time.