It’s About Time! An Explanation of a Metaphysical Puzzle About Objects
Four-Dimensionalism and its solution to the Puzzle of Material Constitution
Written by Julia Brick
If you have a lump of clay and then you mould it into the shape of a statue, is that statue only one object? Or is it instead two objects, a statue and the lump of clay that composes it? This question is the basis of a metaphysical problem called the Puzzle of Material Constitution. In this post, I will describe this problem and discuss one solution to it called Four-Dimensionalism.
A statue and lump of clay is an example used to illustrate a metaphysical problem called the Puzzle of Material Constitution. This problem poses the question asking whether an object and the material that composes it, is one object or two. Those who think that a statue and the clay that composes it is only one object are called monists, while those who think that the statue and clay compose more than one object are called pluralists.
Identity
One way of approaching this problem is to consider identity, asking whether the clay is identical to the statue. From this monist point of view, when Clay materially constitutes Statue, they are identical. This view holds that this means they are simply the same thing. The main problem with the monist identity view is that for two things to be completely identical, they must share all of the same properties. Those who disagree with this view will point out that the statue and the clay do not share all of their properties, and are therefore not identical. For example, a lump of clay has the property that it can be squashed and continue to be a lump of clay, whereas if the statue is squashed it ceases to be a statue. It is essential to Statue that it is shaped like a statue, while Clay does not have this property. Therefore the statue and the lump of clay have differing properties and cannot be identical.
Cohabitation
The pluralist perspective also faces significant problems, for instance, the issues that arise when assuming Cohabitation. Cohabitation assumes that Statue and Clay are two distinct objects that exist at the same time in the same place. Say this is the case, and the statue and clay are squashed by the sculptor. After the squashing, there is no more statue, there is only a squashed piece of clay. The clay still exists while the statue has been destroyed. This presents a problem, because how is it that the same amount of force can be applied to two different objects, and one of them is so completely destroyed that it ceases to exist, while the other continues on? It does not make sense for the statue to be significantly more fragile than the lump of clay, because they are composed of exactly the same matter. Cohabitation as a view must be rejected because it is apparent that it is not possible for two distinct wholes to be composed of only one set of parts.
Temporal parts
As there appear to be convincing arguments against both views, the Puzzle of Material Constitution seems to have no clear answer. However, there is an argument from the pluralist perspective that does not require the statue and the clay to share all of the same properties; or to violate the principle that two objects cannot share one set of parts. Conee and Sider describe this view, which is called Four-Dimensionalism. They write that this requires thinking of time as a fourth dimension. According to this theory, objects have temporal parts.
Temporal parts only exist at one point in time and are temporally smaller than a whole thing. These temporal parts are like slices of time that when put together make up something whole. There is a temporal part of you that existed yesterday, another temporal part of you that existed five minutes ago and yet another temporal part of you that exists right now. Put together, these slices compose you. These temporal parts do not have to share exactly the same properties in order to compose the same object. For example, if you had gotten a paper cut a week ago that has since healed, there is a temporal part of you from a week ago that has a paper cut, but the temporal part of you that exists now does not have that paper cut. Both of these temporal parts compose you, even though they do not share exactly the same properties.
Four-Dimensionalism and the statue and clay
Four-Dimensionalism can then be applied to the statue and the clay example to provide an answer to the Puzzle of Material Constitution. At first, there is a piece of clay that has not been moulded into any defined shape. For all the time that the clay spends like this, it is simply clay. Its temporal parts during this period would compose a piece of clay. Then the sculptor moulds the clay into the shape of a statue for ten minutes, before squashing it back into shapeless clay. The statue existed only for those ten minutes that it was statue shaped. The clay existed before the statue existed and resumed its existence once the statue was squashed. According to this view, Clay and Statue are different objects, but Statue is a part of Clay in the same way that a person’s foot is an object that is still a part of their body.
Four-Dimensionalism solves the problem presented by the Cohabitation view as well as addressing the problem of identity. The problem of Cohabitation involved two distinct objects being composed of only one set of parts, while the two objects had distinct properties from each other. However, from the Four-Dimensional perspective, Statue and Clay are not composed of the same parts, as they each have their own temporal parts as well as their spatial parts. The piece of clay has more temporal parts than the statue, as it existed before as well as after the statue. As such they clearly do not share exactly the same parts and can be considered two distinct objects.
The Four-Dimensionalism perspective addresses the monist problem of identity by disagreeing with the premise that the clay and statue are the same object. Four-Dimensionalism says that the statue and the clay have different properties because they are not the same object and are not identical.
The Puzzle of Material Constitution questions whether a statue made of clay is one object or two. Those who think it is one object are called monists, while those who think there are two objects are called pluralists. Monists face the problem of identity, as it is implausible for the clay and the statue to be identical, because they do not share all of their properties. The pluralist perspective encountered a similar problem, in that it is not possible for two separate objects to occupy the same space and share exactly the same matter if one of them can be entirely snuffed out of existence by exactly the same force that does not have an impact on the existence of the other object. The Four-Dimensionalism perspective introduced temporal parts, which solved both problems, showing that as the clay and the statue have different parts to each other that were previously overlooked before we took the dimension of time into discussion.
Edwards, F. 2013. Problem of Material Constitution [Online]. Youtube.com. Available: https://youtu.be/_HVkeNUV-3M [Accessed 13th November 2020].
Paul, L. A. 2010. The Puzzles of Material Constitution. Philosophy Compass, 5, 579–590.
