Recap: Alyssa Ney's Metaphysics: Chapter 3 - Material Objects

3.1 - What is a Material Object?

• One way to define 'concrete' or 'material' is: existing in space and time (having spatial and temporal properties).
• Another way is to say material objects have at least some mass. However, photons do not have mass and yet are thought of as material. Photons do carry the electromagnetic force. So we might say something is material if it has mass or if it carries one of the fundamental forces.
• Altogether then, a material object roughly is one that has spatial and temporal properties, plus either the property of having mass or of carrying one of the fundamental forces.
• Question: How does being material relate to being concrete?
• My understanding is that all material objects are also concrete, but not all concrete objects are material. If something exists in space and time then it can be affected by other objects in space and time. Even dark matter, if it exists, has mass and therefore has a gravitational effect. However, not all concrete objects are material. Souls, and thoughts, are concrete (at least on some theories of mind), because they are causal (souls cause actions; thoughts are caused by brains). But thoughts are not material; they do not have mass or spatial properties (arguably they do have temporal properties as some thoughts exist before and after other events). Identity theorists who say thoughts are identical to brain states would say thoughts are material objects, but identity theory is highly controversial (so is every other theory of mind).
• (Real quick: on very large cosmic scales dark energy is a theoretical posit that explains the accelerated rate of the expansion of the universe. However, this force should be ripping galaxies apart given the mass of known matter. So dark matter is the other theoretical posit that explains all of the hidden mass in the universe needed to explain why galaxy clusters are holding together despite dark energy.)
• What material objects should we believe exist? A common position is that we must at least accept those fundamental material objects as described in the Standard Model of Particle Physics.
• These include leptons (electrons and neutrinos) and quarks. "There is much disagreement about what else exists . . ." (pg 85)

3.2 - The Paradoxes of Material Constitution

• There are two classic puzzles in material constitution: The Ship of Theseus and the Statue and the Clay.
• Starting with the Ship of Theseus, I will assume you are familiar with the story.
• S1 = the original ship that arrived in Athens from Crete.
• S2 = the original ship after it had every part replaced with a new part.
• S3 = the bonus ship composed of all the parts of the original ship after they were tossed.
• What counts as the real Ship of Theseus?
• Option 1: S1 = S2, S1 =/= S3. (The ship retains its identity after having every part replaced, and the second ship built out of the old parts is a new ship.)
• Option 2: S1 = S3, but S1 =/= S2. (The original ship is destroyed when its parts are replaced, and resurrected when reconstructed out of its old parts.)
• Option 3: S1 = S2 and S1 = S3 (therefore, S2 = S3). (Both ships are the original ship.)
• Option 4: S1 =/= S2 and S1 =/= S3. (Neither ships are the original ship.)
• Argument for Option 1: If you change a single part of the original ship, do you have a whole new ship? In a strict sense yes, if we mean the object has a new set of properties. But in another common sense way it feels strange to say I got a new car when all I did was get new wheels on it. It seems like I have the same car even after getting new wheels. So we might call the ship with one part replaced S1*. But if S1* gets a single part replaced, is it a new object? By the same logic as before, it's the same object. So we have S1**. We can repeat this until every part of the original ship has been replaced, which gets us S2. Because S1 = S1* = S1** and so on, then this new ship, S2, is the same as S1. Intuitively, it feels like if I kept replacing parts of my car, it would be fine to talk about my car as if I never got a new car but simply modified my car.
• Argument for Option 2: One of the key properties, you might think, of the original ship was its composition. So the ship built out of the old parts, having the exact same composition as the original ship, is identical to the original ship. Intuitively, if I took my car apart, every single part, and then reassembled it, it would be the exact same car. Even if I disassembled the car and sent every part to a different location, and then each location sent each part to a new central location, and the car was reassembled there, that wouldn't be a relevant difference from reassembling the car in my workshop. So S1 = S3.
• Argument for Option 3: We just saw a good argument for thinking S1 = S2. And we just saw a good argument for thinking S1 = S3. So why not accept both arguments and say S1 = S2 and S1 = S3? The problem can be revealed with the help of Leibniz's Law, which says that if x = y, then x and y must have identical properties.
• You might think Clark Kent and Superman have different properties, and yet they are identical. So is this a counterexample?
• No, because, arguably, the essential property of Clark Kent is his personhood, and the personhood of Clark Kent (and all the properties that entails) is identical with the personhood of Superman. It's the same person.
• So with Leibniz's Law in hand we can see that S2 =/= S3. The two ships have different properties. Most obviously, they exist in different locations! So Option 3 fails.
• Argument for Option 4: This says the original ship was destroyed and two new ships have arrived. This option is attractive if you want to say no, S1* is not the same as S1; replacing one part does technically give you a new ship. So after the first part is replaced, technically the original is destroyed and you have a new ship. Then the ship built out of the old parts is also a new ship, because it was built at a different time than the original was built. Remember, by Leibniz's Law, if there's even one difference in properties between x and y, then x =/= y. So while S3 and S1 have the same material composition, they have different histories, and thus different properties in other respects. So they can't be the exact same object.
• So it looks to me like there are fairly satisfying arguments for Options 1, 2, and 4. It will depend on what exactly an object is, on what properties we consider essential vs accidental to the identity of an object, on what properties are the most relevant to us when we label objects, and on how strict we want to be on the overlapping of all conceivable properties.

I will save the problem of the statue and the clay for another time.

3.3 - The Problem of the Many

• Diachronic identity = identity over time.
• Problem of the Many = Objects don't seem to have well-defined boundaries. Take your body for instance. Let's say it's composed of exactly 7*10^27 atoms. We can call this C. We can imagine C-, which has one fewer atom. We can imagine C--, which has even one fewer. We can even imagine C+ and C++, which are objects composed of your body plus one or two atoms. It doesn't seem like a single atom makes a relevant difference in being your body. But that means we have a bunch of objects that have just as good a claim to be your body. By accepting the one, you accept the many. Because of this, Peter Unger rejects the one, rejecting the existence of composite objects.
• This seems like a harmless problem. Based on previous discussions, it seems easy to say that C is the only object we are committed to. C-, C--, C+, and C++ are all fictional objects that are ever-so-slightly different from the real object. Because we are not committed to fictional objects, we are not committed to the many.

3.4 - The Special Composition Question

• This comes from Peter van Inwagen. In what circumstances do some objects compose something?
• Special composition question: For any x's, when is it the case that there is a y such that the x's compose the y?
• Mereological sum: A collection of parts that do not make a whole. Maybe you don't have a body, only a mereological sum of the atoms that you take to make up your body.
• Proper part: x is a proper part of y when x is part of y and x is not identical to y. (We specify proper part because, "Strictly speaking, every object is a part of itself." pg 100) (Henceforth, when I say 'part' I mean 'proper part' unless otherwise stated.)
• Simple: an object without parts.
• Whole: an object with parts.

3.5 - Moderate Answers to the Special Composition Question

• A moderate answer says that composition happens some of the time. An extreme answer says that it happens all the time or none of the time.
• One principle we might apply is the contact principle, where parts that come into contact with each other form a whole. However, our solar system is made up of objects that are far away from each other. Another problem is that objects contain a great deal of empty space; fundamental particles combine to form atoms and molecules, but they don't touch strictly speaking. A further problem is that there are cases where objects touch but don't form a whole, such as when two people shake hands.
• Peter van Inwagen rejects the contact principle. He considers and rejects a number of other principles as well (pg 102).
• My principle: Human relevance. We compose objects by combining, in our minds, those properties that are relevant to us. This view might be consistent with mereological nihilism though.
• Van Inwagen holds a hybrid view. He subscribes to mereological nihilism when it comes to all objects except himself and other persons and organisms. Only living things are complex objects (wholes) on this view; everything else is a mereological simple.
• So van Inwagen believes that the x's compose the y's when the x's participate in an activity that constitutes a life.

3.6 - Mereological Nihilism

• Mereological nihilism = the view that there are no wholes (complex objects; objects made up of parts), only simples. This is one of the extreme responses to the problem of composition.
• An argument in favor of nihilism that immediately jumps out is found in parsimony. I said in a previous recap how much I admired nominalism and the A theory of time for their beautiful simplicity. I also mentioned we are not committed to objects that can be reduced to something more fundamental. On mereological nihilism, we reduce all wholes to simples, and so we are not committed to wholes.
• Van Inwagen gives this argument against nihilism, which we've already alluded to:
• 1 - I exist.
• 2 - I am not a simple.
• 3 - So at least one whole exists.
• 4 - So mereological nihilism is false.
• One way to deny premise 2 is to adopt substance dualism. This view says I am not a material being, but an immaterial soul. Souls are irreducible simples; they are not wholes with parts. So if we are souls, then we are simples, and if we are simples, then that further supports the view that only simples exist.
• Dustin Crummett has defended both mereological nihilism and substance dualism in this way.
• A worry about mereological nihilism is the worry over the status of the fundamental particles as simple. For all we know, electrons and quarks are not composed of anything. But we've been wrong before. Atoms were thought to be simples, and now we know they are not. What if matter turns out to be infinitely divisible and there are no simples?
• While parsimony can be beautiful, I'm not sure that applies here. Nihilism says there are only mereological sums, no wholes. But when I talk about ordinary objects like my keyboard or laptop or laundry basket or mattress, I don't have in mind a mereological sum. To talk of objects in this way would be to emphasize what they are made out of. But we do talk about objects in a holistic way, emphasizing instead the combination of properties that is most relevant to us. The fact that my laptop is technically made up of atoms isn't all that useful. So 'laptop' doesn't emphatically refer to an object made up of atoms (even if that's technically correct); it refers to an object that has a shape and size to it, and causes impressions of a certain rectangular shape to appear in the first-person experience for those with sight, and enables me to perform tasks like writing philosophy. While this doesn't sound like a substantial objection against nihilism, it points to perhaps the main objection (which also might not be substantial) that mereological nihilism feels unsatisfying; it doesn't quite capture that feeling of oneness that objects have. 

3.7 - Mereological Universalism

• This is the other extreme response to the composition problem.
• Mereological Universalism = Any two disjointed (= non-overlapping) material objects compose a further object.
• David Lewis defended this view. (I believe Graham Priest does as well. Knowing Priest's connection with Lewis, I suppose that wouldn't surprise me.)
• This view entails that wholes exist at every opportunity. Any imaginable combination of objects forms a real further object.
• The parsimony argument in favor of mereological nihilism applies here as an objection. You have this hideous, massively bloated ontology with universalism. I'm also not sure how to make sense of the view. There's a whole composed of my right foot and the Eiffel Tower? I don't think so. Philosophy should be beautiful, not ugly.

3.8 - Vagueness

• David Lewis calls vagueness semantic indecision. You could also call it semantic indeterminacy; vagueness is when it's not clear what a word or phrase or sentence means.
• Vagueness is meant to challenge those who reject either extreme response. The moderate responses leave it vague how composition occurs when it does.

3.9 - Back to the Paradoxes

• Mereological nihilism has an easy time solving the puzzles of composition. There never was a Ship of Theseus to begin with; there were only simples arranged ship-wise.