| 14524 | Bodies are combinations of shape, size, resistance and weight [Epicurus] |
| Full Idea: Epicurus said that body was conceived as an aggregate of shape and size and resistance and weight. | |
| From: Epicurus (Principle Doctrines ('Kuriai Doxai') (frags) [c.290 BCE]) | |
| A reaction: [Source Sextus 'Adversus Mathematicos' 10.257] Note that this is how we 'conceive' them. They might be intrinsically different, except that Epicurus is pretty much a phenomenalist. |
| 12971 | If two individuals could be indistinguishable, there could be no principle of individuation [Leibniz] |
| Full Idea: If two individuals were perfectly similar and equal and, in short, indistinguishable in themselves, there would be no principle of individuation. | |
| From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.27) | |
| A reaction: This seems to be the main motive for Leibniz's unusual claim that there cannot be two indiscernible individuals, but it looks suspiciously like an a priori claim made about what should be an a posteriori discovery. Are electrons distinguishable? |
| 19379 | The law of the series, which determines future states of a substance, is what individuates it [Leibniz] |
| Full Idea: That there should be a persistent law of the series, which involves the future states of that which we conceive to be the same, is exactly what I say constitutes it as the same substance. | |
| From: Gottfried Leibniz (Letters to Burcher De Volder [1706], 1704), quoted by Richard T.W. Arthur - Leibniz 4 'Applying' | |
| A reaction: The 'law of the series' is a bit dubious, but it is reasonable to say that a substance is individuated by its coherent progress of change over time. Disjointed change would imply an absence of substance. The law of the series is called 'primitive force'. |
| 10194 | Two things can only be distinguished by a distinct property or a distinct relation [Black] |
| Full Idea: The only way we can discover that two things exist is by finding out that one has a quality not possessed by the other, or else that one has a relational characteristic that the other hasn't. | |
| From: Max Black (The Identity of Indiscernibles [1952], p.67) | |
| A reaction: At least this doesn't conflate relations with properties. Note that this idea is clearly epistemological, and in no way rules out the separateness of two objects which none of us can ever discern. Maybe the Earth has two Suns, which imperceptibly swap. |
| 17668 | It is likely that particulars can be individuated by unique conjunctions of properties [Armstrong] |
| Full Idea: For each particular it is likely that there exists at least one individuating conjunction of properties, that is, a conjunction of properties such that the particular instantiates this conjunction and nothing else does. | |
| From: David M. Armstrong (What is a Law of Nature? [1983], 02.3) | |
| A reaction: Armstrong commits to a famous Leibniz view, but I don't see his grounds for it. There is nothing incoherent about nature churning out perfect replicas of things, such as quarks and electrons. Would we care if two pens were perfectly identical? |
| 8520 | An individual is a union of a group of qualities and a position [Quinton, by Campbell,K] |
| Full Idea: Quinton proposes that an individual is a union of a group of qualities and a position. | |
| From: report of Anthony Quinton (The Nature of Things [1973], Pt I) by Keith Campbell - The Metaphysic of Abstract Particulars §5 | |
| A reaction: This seems the obvious defence of a bundle account of objects against the charge that indiscernibles would have to be identical. It introduces, however, 'positions' into the ontology, but maybe that price must be paid. Materialism needs space. |
| 17647 | Kripke individuates objects by essential modal properties (and presupposes essentialism) [Kripke, by Putnam] |
| Full Idea: The difficulty is that Kripke individuates objects by their modal properties, by what they (essentially) could and could not be. Kripke's ontology presupposes essentialism; it can not be used to ground it. | |
| From: report of Saul A. Kripke (Naming and Necessity lectures [1970]) by Hilary Putnam - Why there isn't a ready-made world 'Essences' |
| 15455 | Total intrinsic properties give us what a thing is [Lewis] |
| Full Idea: The way something is is given by the totality of its intrinsic properties. | |
| From: David Lewis (Extrinsic Properties [1983], I) | |
| A reaction: No. Some properties are intrinsic but trivial. The 'important' ones fix the identity (if the identity is indeed 'fixed'). |
| 8303 | Criteria of identity cannot individuate objects, because they are shared among different types [Lowe] |
| Full Idea: Criteria of identity never unambiguously determine the kind of objects to which they apply, since many different types of objects can be governed by the same criteria. Cats and dogs share the criterion of identity for animals in general. | |
| From: E.J. Lowe (The Possibility of Metaphysics [1998], 10.3) | |
| A reaction: So how do you individuate the type of an object? You could identify 'the thing I dug up yesterday' without being able to individuate it. You can individuate 'the cleverest person in Britain' without being able to identify them. |
| 16680 | Scholastics thought Quantity could be the principle of individuation [Pasnau] |
| Full Idea: Quantity was a leading scholastic contender for the principle of individuation. | |
| From: Robert Pasnau (Metaphysical Themes 1274-1671 [2011], 14.4) |
| 16785 | If you reject essences, questions of individuation become extremely difficult [Pasnau] |
| Full Idea: Given the accepted linkage between a thing's essence and its identity, the rejection of essences makes a complete mess out of questions of individuation. | |
| From: Robert Pasnau (Metaphysical Themes 1274-1671 [2011], 27.6) | |
| A reaction: I note that he talks of a thing having 'identity', contra the view of identity as a two-place relation. I agree with this, but there is a chicken-egg problem. Do I perceive an identity and surmise an essence, or surmise an essence and deduce identity? |