| 16792 | If parts change, the whole changes [William of Ockham] |
| Full Idea: That is not the same whole that does not have the same parts. | |
| From: William of Ockham (Commentary on the Sentences [1320], IV.13), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 29.2 | |
| A reaction: In isolation, this is mereological essentialism (as Pasnau confirms), which is incredibly implausible, if I cease to be the same person when I cut one of my fingernails. |
| 12884 | The same whole ceases to exist if a part is lost [Leibniz] |
| Full Idea: We cannot say - with complete fidelity to the truth of things - that the same whole continues to exist if a part of it is lost. | |
| From: Gottfried Leibniz (New Essays on Human Understanding [1704], 2.27.11) | |
| A reaction: This is the reference Simons 1987:319 gives when he claims that Leibniz accepts mereological essentialism. I think this is mereological necessity of identity, but not what I call 'essentialism'. That has to distinguish essential from non-essential. |
| 12781 | A composite substance is a mere aggregate if its essence is just its parts [Leibniz] |
| Full Idea: An aggregate, but not a composite substance, is resolved into parts. A composite substance only needs the coming together of parts, but is not essentially constituted by them, otherwise it would be an aggregate. | |
| From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29) | |
| A reaction: The point is that there is more to some things than there mere parts. Only some unifying principle, in addition to the mere parts, bestows a unity. Mereology is a limited activity if it has nothing to say about this issue. |
| 12139 | Mereological essentialism says that every part that ensures the existence is essential [Brody] |
| Full Idea: Mereological essentialism (whose leading advocate is Chisholm) says that for every x and y, if x is ever part of y, then y is necessarily such that x is part of y at any time that y exists. | |
| From: Baruch Brody (Identity and Essence [1980], 5.6) | |
| A reaction: This sounds implausible, especially given the transitivity of parthood. Not only are the planks that constitute Theseus's Ship now essential to it, but all the parts of the planks, every last chip, are as well. |
| 8443 | Mereological essentialism says an entity must have exactly those parts [Sosa] |
| Full Idea: Mereological essentialism says that nothing else could have been the unique entity composed of certain parts except the very thing that is composed of those parts. | |
| From: Ernest Sosa (Varieties of Causation [1980], 2) | |
| A reaction: This sounds initially implausible. It means the ship of Theseus ceases to be that ship if you change a single nail of it. Whether we say that seems optional, but if we do, it leads to the collaps of all our normal understanding of identity. |
| 14757 | Mereological essentialism says an object's parts are necessary for its existence [Sider] |
| Full Idea: Mereological essentialism says that an object's parts are necessary for its existence. ....It is literally never correct to say that an thing survives a change in its parts. | |
| From: Theodore Sider (Four Dimensionalism [2001], 5.7) | |
| A reaction: Chisholm is well known for proposing this view. Sider adds a possible toughening clause, that the parts are also sufficient for the object's existence. This is a philosophers' notion of identity, not the normal English language concept. |
| 12874 | An essential part of an essential part is an essential part of the whole [Simons] |
| Full Idea: An essential part of an essential part is an essential part of the whole. | |
| From: Peter Simons (Parts [1987], 7.4) | |
| A reaction: Sounds beyond dispute, but worth pondering. It seems to be only type-parts, not token-parts, which are essential. Simons is thinking of identity rather than function, but he rejects Chisholm's idea that all parts are essential. So which ones are? |