In the first third of this course, we will be focusing on Puzzles of Objects. 'Objects' here includes ordinary things such as rocks and trees, ships, statues, and cats. The puzzles surrounding these sorts of objects are the result of tensions or conflicts with commonsense 'truisms', or ordinary intuitions, we hold about these very ordinary objects. Let us look at some of the intuitive principles concerning ordinary objects. Then we will look at four puzzles that fall out of these seemingly unproblematic principles. As hard as it may be to believe, for each one of the principles that is listed, there will be some philosopher who denies it in order to avoid the puzzles that result.

PART 1: Commonsense Truisms

(1) There are (material) objects.

Rocks, trees, ships, statues, and cats, etc. exist. They are out and about in the world, taking up space. You bump into them, you trip over them, you climb them, make them, pet them, and yell at them. This may seem to be a no-duh principle, but some philosophers will insist that it is false, so it is important that we flag it as one of our commonsense 'truisms.' We do think, most of us, that objects such as ships and cats and so on exist.

(2) Objects have (or are made up of) parts.

Look at your book, Material Constitution. It has parts. It has a front cover, a back cover, and over 350 individual pages in between. It has a left half and a right half, a top part and a bottom part. If I wanted, I could seemingly and easily demonstrate the divisibility of the book into parts by taking a chainsaw to it and slicing it right through the middle, lengthwise. Or we could rip out the pages one by one, demonstrating how each is a different part of the book than another. Or we could look at it under a microscope and examine all of the many tiny paper fibers that make up one page, and add these up to show how the whole book is made up of untold many tiny fibrous parts. And we think something similar about rocks and trees and cats and ships. These objects not only exist, as our first principle tells us, they exist and they all have parts.

Moreover, we think that these objects are made up of its parts. Suppose we go through all of the book's parts one by one--page by page, fiber by fiber, cover to cover. We say something like, "here is one page", "here is another", "here is the 350th page", "here is the back cover", etc. After we have gone through and accounted for all of the book's parts, suppose someone asks "Ok, fine. But where is the book?" Understandably, we would be confused by this person's question. We might find ourselves saying something like, "What do you mean, where is the book? The book just is all of its parts; the book is where the parts are." In this way, we not only think that objects have parts, but that the parts are importantly related to the object in question--the object is made up of its parts.

(3) An object can gain and lose some of its parts and remain the same object.

Take a look at your hand. It is a certain size and a certain shape and a certain color. But think about when you were an infant. Your hand was much smaller, much squattier in shape, and probably even a different color than it is now. Your infant hand no doubt lost some parts and then gained new ones, resulting in the hand you have now. But the hand you have now, no matter the parts that it gained and lost since you were an infant is still your hand. You wouldn't, for example, look down at your hand one day and yell in shock and surprise, "Holy macaroni! This is not my hand!! Where the flip did my hand go?! Who stole my hand?!?"  When it comes to objects such as your hand, we certainly talk about it and treat it as if it is the same hand over time, even though we recognize that some of its parts are different.

To put the point another way: imagine that you could 'see' all of the cells and particles that make up your hand right now. Suppose you do nothing all day but watch your hand, from the moment you wake up until the moment you go to bed at night. What you would see, if you really did have microscopic eyes, is that little cells and molecules are dropping and flaking and being brushed off all of the time. In just an 18 hour day, you would see particles fall off of your hand, and you may even see new ones being regenerated. Yet we do not typically say that your hand has changed. We would still say that the hand--despite the losing and gaining of small parts--is still your hand. We allow that objects such as your hand, in other words, can gain and lose some of its parts and remain the same object.

(4) An object cannot lose all of its parts, or gain entirely new ones, and remain the same object.

Despite the intuitiveness of principle (3), there does seem to be a limit as to how many parts we think and object can gain or lose before it ceases to be the same object. This limit is expressed by principle (4). To see this, go grab a coffee mug. The coffee mug is made of many little coffee mug bits--maybe lots and lots of plastic or ceramic or metallic particles. It's got a handle and a "lip" and maybe even a spill-proof cover. Now imagine that you close your eyes for just a minute and when you re-open them, all of the parts of the mug are gone. All of them. Now ask yourself: is the mug still there? Presumably, an object cannot lose all of its parts and remain the same object; once an object loses its parts, the object is lost, too.

Moreover, it doesn't seem as if an object can have all of its parts replaced and remain the same object, either. Imagine your mug as you did before, and imagine that you close your eyes for a minute. Only this time, when you re-open them, imagine that all of the parts of the mug are gone, but they were all replaced by bits of cous-cous. That is, for every bit of plastic or ceramic or metal that made up your original mug, it has now been replaced by a bit of cous-cous. So now, when you re-open your eyes, you look down and see a mound of mug-shaped cous-cous. Now ask yourself: is this cous-cous mug-shaped thing your mug? Presumably, no. An object cannot have all of its parts replaced by other parts and remain the same object.

(5) An object can survive or endure through time.

Independent of the issue about objects and their parts, one intuition that we all seem to have about objects is that they survive or endure through time. We typically think that objects--like rocks and trees and cats and ships--can survive from one instant to the next, for long moments at a time, from minutes to hours to years.

If you don't find this principle intuitive, think how unintuitive it would be if this principle were false: no object survives or endures through time. This would mean that the smallest, most minute, increment of time would carry with it the destruction of untold many objects, and that each new smallest, most minute increment of time would carry with it the creation of just as many untold many objects. If objects couldn't survive or endure through time, then objects would be 'popping' in and out of existence all of the time. This is not only counterintuitive when it comes to the nature of objects, but conflicts with our intuitions about ownership and responsibility as well (e.g., 'you' could rob a bank and then defend 'yourself' in court by claiming that the person in court, 'you', is not the same as the person who robbed the bank. However, it would be hard for you to defend yourself, since such a defense would take time to say, and by your own reasoning, 'you' would be popping in and out of existence at every new moment, and so the person who began the defense would not be identical to the person who ended it. Bummer.)

(6) No two material objects can occupy the same place at the same time.

Look at your hand. Now take your pencil. Can you make it so that your hand and your pencil take up the same place at the same time? I can even make it a little easier: can you make it so that your pencil and your hand overlap even just a little bit, so that your pencil and your hand are at least partly taking up the same place at the same time? Suppose you are a bit brave (and a bit of a moron) and decide to take me up on the challenge. You take a deep breath and jam the pencil straight through the top of your hand until it comes out the bottom. So there you are, with a pencil jammed through your hand. Have you met the challenge? Have you shown me that two things can be at the same place at the same time, even just partly? Of course not. That is because anywhere the pencil is, your hand isn't. If you don't believe me, take the pencil out and you will see a pencil-sized whole (where little hand bits used to be). So try as you might, no two material objects can occupy the same place at the same time.

(7) Leibniz's Law: Necessarily, an object a and an object b are identical if and only if a and b have all of the same properties.

This principle is actually a philosopher's principle about the identity relation. But I believe that it is intuitive as well, and makes sense if you think about it a minute, even if it is not so common a principle.

First, whenever there is the phrase "if and only if" this means that this is a bi-conditional statement. There are two parts to the statement, (i) and (ii):

    (i) An object a and an object b are identical if a and b have all of the same properties.
    (ii) a and b have all of the same properties if a and b are identical.

The intuitive idea is that numerically identical object"s" have all of the same properties. Suppose someone were to reason as follows: "Superman and Clark Kent are different guys because Clark Kent wears glasses and Superman doesn't." What the person is trying to get at is that Superman and Clark Kent are different guys because "they" presumably have different properties: Clark Kent has bad eyesight and Superman doesn't. The problem, however, is that if Superman and Clark Kent are identical, then it is not the case that Clark Kent wears glasses and Superman doesn't: if Clark Kent wears glasses, Superman does too, since "they" are the same guy! If Superman has xray vision, Clark Kent does, too. The idea is that if "two" things really are two, then they are not identical, and so they must differ in at least some of their properties. On the other hand, if a thing a and a thing b are identical, then we know that 'they' are not two, but one, and there is no property that a has that b does not have. Going the other way, if a and b have no distinguishing properties--if a and b have all of the same properties--then a and b are identical.

We will discuss this principle at length in class. For more detail on Leibniz's Law--and, in particular, the Identity of Indiscernibles--go here.


PART 2: Puzzles of Objects

(I) The Debtor's Paradox (also known as the Marriage Paradox, the Growing Argument, and the Paradox of Increase):

Suppose you have finally decided to marry the love of your life. The two of you exchange vows and promise to be together forever. However, seven years later you come home and find the closets empty of your spouse's belongings, some suitcases missing, and the following note propped up on the bedroom bureau:

Understandably, you are heartbroken. But, more importantly, you are feeling duped. Surely something must be wrong with the above line of reasoning (otherwise divorce proceedings would be a much swifter process and there would be no need for expensive divorce lawyers). But where did your spouse's reasoning go awry?

As we discuss this puzzle in class, notice which of the above commonsense 'truisms' are at work here. First, this puzzle uses principle (1), since it--at the very least--assumes that objects such as people, or human beings, exist. It also uses principle (2), since it assumed that human beings are made up of parts--bits of molecules and cells and material particles. Moreover, in this particular formulation of the puzzle, it assumed that human beings are entirely made up of material parts (contrast this with a Soul View--which we will discuss in the second part of the class and is explained in the Perry handout here--where a human being is partially made up of material parts, but has immaterial parts as well (the soul)). It also assumes principle (3), (4), and (5) since it assumes that a human can gain and lose some of its material parts, and survive or endure through time, but that it cannot lose all of its parts and still be the same object. Finally, the above principle appeals to principle (7) because it compares the properties of a collection of molecules at one time (the exchange of marriage vows) to the properties of a collection of molecules at a later time (the collection of molecules that is writing the note, 7 years after the wedding). Since the collection of molecules at one time differs from the collection of molecules at a later time, then by Leibniz's Law, the collections are not identical. Thus, the collection of molecules that was standing at the alter is not identical to the one writing the letter 7 years later.

You might also think that principle (6) is subtly at play here, since there was a switch in talk from "human being" to "collection of molecules." And certainly one could reason from principle (6) that a human being must be identical to the collection of molecules that make it up, since to deny this would be to deny (6). However, the premise "human beings are made up of a collection of skin and bones and tissue and veins and millions and millions of atoms and particles" may also be seen as assuming that human beings just are a collections of material parts, and that's it. In this way there would be no need to argue for the identity of a human being and its parts from principle (6); it would just be assumed in one of the premises.

(II) The Ship of Theseus

There is a separate handout (html) for this one. To see it, go here.
 
As we discuss this puzzle in class, notice parallels between this and the Debtor's Paradox. Both use principles (1)-(5), and (7) in similar ways. This puzzle assumes (i) that ships exist, (ii) that ships are made up of parts (in this case, boards, a mast, and a sail), (iii) ships can survive the loss of some of it's parts, but (iv) it can't survive the loss or replacements of all of its parts, and it uses Leibniz's Law to keep track of which things are identical or distinct from which. The difference between this puzzle and the Debtor's Paradox, however, is that this one adds a twist: the original parts of the original ship (boards, mast, sail, etc.) are kept around, collected, and assembled at the end of 102 years. Thus, we have the added complication that there are two competitors for the identity of the Ship of Theseus. Leibniz's Law seems to incline us towards one of the candidates for the Ship of Theseus (the one with all of the original parts), while our confidence in principles (3) and (5) incline us towards the other candidate (the one that has been on sea and has been the home for all of the crew).

Also, notice that one answer available is to say that there are two Ships of Theseus--that both of the candidates qualify as being the Ship of Theseus. But what intuition or principle would this conclusion violate? And would such a claim be worth denying this (or these) principles? We'll discuss this in class.


(III) Tib and Tibbles

Imagine that we have a cat named Tibbles who is a regular looking and ordinary cat. When we meet him one morning, Tibbles looks like so:



In the morning, he steps outside and goes about his normal cat-like business. However, a terrible tragedy befalls Tibbles when he gets too close to a lawnmower: his tail gets lopped clean off! At night he comes back indoors looking like so:

 

Let us name the name the part of Tibbles that came back--the purplish-blue part--Tib. In the morning, it seems that both Tibbles and Tib exist. After all, we can see that one is one color (Tib is purplish-blue) and one is another (Tibbles is purplish-blue in a Tib-shaped part and teal-green in a tail-shaped part). Moreover, it seems clear that in the AM, Tibbles is not identical to Tib. For Tibbles (in the morning) has a tail and Tib doesn't (in fact, by definition, Tib never has a tail), so by Leibniz's Law they are distinct. But in the evening, Tibbles does not have a tail (that is, after all, why he is so sad), and Tib doesn't either. So what, then, is the difference between Tib and Tibbles in the evening? If you say nothing, then by Leibniz's Law, we will have to claim that Tib is identical to Tibbles. But how could two distinct things at one time become one thing at a later time?

(IV) Goliath and Lumpl

Imagine that Sam the sculptor has decided to make a statue of Goliath. However, due to an odd superstition, Sam prefers to sculpt one half of the statue, and then the other, and then he puts them together after the halves are complete. So, on Day 1, he sculpts both the top half and the bottom half of Goliath. On Day 2, he sticks the two halves together and lets the statue harden. On Day 3, he realizes the endeavor was a complete failure, and takes a sledgehammer to the statue, smashing it to smithereens.

Suppose that lumps of clay are those bits of clay that are connected to other bits of clay, and that statues are what we ordinarily think they are--certain formations created to represent something and made of some kind of material like clay and bronze and what-not. Let us call the lump of clay that Goliath is made out of, Lumpl, and let us call the statue, Goliath. On Day 1, it seems that neither Lumpl nor Goliath exist. Yet on Day 2, it seems that Goliath and Lumpl come into existence at the same time. On Day 3, however, it seems they go out of existence at the same time (as soon as 'they' are smashed). So it would seem that both Lumpl and Goliath exist at the same place, at the same time, and for the same amount of time. But wait! Doesn't this violate principle (6)?

"Well, perhaps," you think, "Lumpl and Goliath are identical. Then principle (6) would not be violated." Yet by Leibniz's Law, it seems that Lumpl and Goliath are distinct. For Lumpl has a property that Goliath doesn't have: Lumpl could survive being smushed or rearranged, but Goliath couldn't. And Goliath has a property that Lumpl doesn't have: Goliath could survive the loss of a toe or an arm, say, but Lumpl couldn't. So by Leibniz's Law it seems that Lumpl and Goliath are distinct, yet then how could they both be in the same place at the same time? Does this mean we should give up principle (6)?

Discussion in class...

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