There is a common sense view that there are such things as planets, rocks, tables, organisms, etc - all of them wholes or aggregates made up of parts. This belief in aggregates creates metaphysical puzzles. One of the more discussed puzzles is Peter Unger’s Problem of the Many.
Basically the Problem of the Many can be illustrated as such: You have a cloud in the sky made up of an aggregate of many water particles. Consider a larger aggregate of all these water particles plus some water particle floating nearby. Is this latter aggregate itself a cloud? It would be strange to not think it so since it is extremely similar to the former aggregate, just a smaller aggregate, equally well deserving of the label cloud. The right thing to think here is that the cloud in the sky isn’t just a cloud, but many overlapping clouds. This doesn’t seem implausible for a cloud, but what about a cat - which is also a cloud of microparticles. Is a cat just many overlapping cats?
The Problem of the Many
Looking at the cloud example again, from a far we get a clearly defined line between cloud and not cloud, but when looking up close the boundary is not so sharp. At the edges the density of water particles fades gradually. The question becomes whether we should count these fainter or less defined cater particles.
Why is particle A on the edge any less deserving than particle B to be cloud since they’re very similar. Each seems to be proper for fitting the label of cloud. So in this case we end up with many clouds, hence the problem of the many. Some may say the example of clouds is too easy, but the problem crops up with everything because things are really clouds of microparticles, even organisms.
Summing it up in a formula:
(1) There is a cat on the mat, Tibbles, an aggregate of many, many tiny particles.
(2) There is no more than one cat on the mat.
Tibbles is an aggregate of Tibbles and all the borderline parts of Tibbles, p1, p2,…pn. We can think of Tibbles as the aggregate of Tibbles plus all the borderline parts except p1, and Tibbles plus all the borderline parts except p2, etc. If we take it as c1 is Tibbles plus all the borderlines except p1, c2 everything except p2, etc we assume then;
(3) There are such things as c1, c2,…
Next, we assume that c1, c2, etc are cats as Tibbles is very similar to c1, c2,…
(4) Each of c1, c2,… is a cat.
Finally, we assume cats c1, c2 are not the same cat. Why are they different? Because c1, has different parts than c2, c3, etc. Remember c1 is the aggregate of Tibbles plus the borderline parts except p1.
(5) For each of c1, c2,…, it is not the same cat as any other c1, c2,….
The mereological nihilist believes there are no aggregates, no wholes with parts. The material world is composed entirely of simples: objects with no parts. There is no planets, rocks, tables , chairs nor organisms.
Even though there are strong evidence of planets, rocks, tables, etc, they just appear planet-wise, rock-wise, table-wise, etc. We can’t determine if there is something even higher up, a further object that these arrangements make up.
The appeal to this view is that by not believing in things like planets, rocks, tables, etc allows you to avoid all these metaphysical puzzles.
Peter van Inwagen came up with a question known as the Special Composition Question: What are the conditions under which several things compose a whole made up of those things?
Van Inwagen coined the term nihilism for the answer of no conditions. He viewed that we have a spectrum with nihilism at one end. The other end can be summed up like this: the condition under which several things compose a larger thing is just that several things exist. If nihilism is when there no conditions then when there are always conditions you have universalism. So if we have somethings that are a, b, c, they are just an aggregate of something.
Moderatism suggests there are conditions where composition occur and other conditions where it doesn’t. Moderatism can be broken down into parts:
Offers a simple, nontrivial statement of the conditions under which composition occurs. How? Several things a,b,c,… compose something x if and only if x is an aggregate of a,b,c,….
There are circumstances under which several things compose something, circumstances under which several things don’t compose anything, and there is a simple, nontrivial description of what makes the difference between these circumstances.
It is a brute fact that arranging matter Tibbles-wise makes for composition of a cat and it’s a brute fact that arranging matter c1-wise, c2-wise, etc does not make the composition of a cat.
There are conditions which composition happens and conditions under which it does not, but there are also conditions in which it is neither definitely true nor definitely false.
Arranging matter Tibbles-wise makes for composition of a cat, but arranging matter c1-wise, c2-wise, etc is not definitely a cat - something along the lines of a probability of being a cat.
Universalism is the view that if there are things a,b,c,… they compose other things; so there are things like planets, rocks, tables, etc. The problem with this account is that you also have things like table-rocks (spatially scattered wholes composed of tables and spatially distant rocks). The view is that there are more material objects than can be dreamed of by the commonsense opinion.
The idea is to distinguish between the masses of feline flesh which are c1, c2, and so forth, and the cat, Tibbles, they constitute. C1, c2, etc aren’t cats, but cat-constituting masses of feline.
This is the idea that c1, c2,… aren’t in fact many cats. This idea came from Hud Hudson. He pointed out that philosophers typically treat the parthood relation as either a two-place relation of a part to whole. For example, the tire is a part of the car. Or a three-place relation of part to whole and time, the tire is a part of the car yesterday. Hudson argued for a slight amendment to this.
Last chapter Peter Geach suggested that there are many kind-relative identity relations: the relation of being the same human. But these relations can happen where one doesn’t apply to the other; the same person can be the mayor of the town and also the President of the school board, but it’s not true that mayor of the town is some official personage as the president of the school board.
Geach views that this idea can be also applied to Tibbles and c1, c2, … cn. C1, c2, … cn are all masses of feline flesh, are the same cat, though not the same mass of feline flesh. One cat, many masses of flesh.
David Lewis defends what is best described as simple universalism. An answer to the Special Composition Question, with classical, nonvague existence and identity, no constitution, and no multiple location.
Lewis would say there are billions of cats on the mat with Tibbles (cats are made up of many microparticles). It sounds crazy, but Lewis would say this depends on the context. In a philosophical context there is nothing wrong with this view, but in unphilosophical context this would be crazy. How does he remedy this?
One proposal is the semantics of vague terms. Terms like tall, thin or bald. The problem with these terms is that no one has clearly defined the boundaries of what makes someone tall, thin or bald. In each case, at what point does one cease to be average and become tall, average and become thin, or enough hair to having not enough? There are obviously clear cases of tall, thin and bald, and there are borderline ones. In everyday social talk we can decern enough of what is being stated.
Lewis views that this relates to our same issue with Tibbles.
For everyday contexts, what matters isn’t identity but almost identity. He suggests things are not completely identical, not completely distinct; they are some of each. When things are closer to the identity end, sharing almost all their parts in common, they are almost identical.