Physics & Metaphysics Handout 8

Physics & Metaphysics Handout 8

H.S. Hestevold Spring 2014

THE METAPHYSICS OF IDENTITY

Where we are headed. For the next week or two, the focus will be on metaphysical problems involving identity [Endurantism versus Perdurantism] and then time [Dynamic Time versus Static Time]. Why so? Many metaphysicians now believe that theories about identity are intimately connected with theories about time that the Perdurantist’s theory of identity goes hand-in-hand with Static Time and that the Endurantist’s theory of identity goes hand-in-hand with Dynamic Time. And why does this matter with respect to physics? The bottom line: There are philosophers and physicists who believe that Einstein’s Special Theory of Relativity [STR] requires (or at least counts in favor of) Static Time. Is this true? If so, then evidence for STR also counts as evidence for Static Time. And if Static Time is linked with Perdurantism, then the evidence for STR counts in favor of the Perdurantist’s theory of identity. (By the same token, if philosophers have strong evidence for Endurantism instead, then this would count as evidence against Static Time and thereby against STR!)

I.Introduction

Have you ever seen the original copy of The Declaration of Independence in the National Archives in Washington DC? Perhaps you have seen John Hancock’s actual signature – the ink that Hancock himself applied to that piece of parchment. Or, you may have seen a painting by one of the great masters – a 350-year-old somber portrait by Rembrandt or one of van Gogh’s scenes painted more recently during the late 19th century. You may have been moved when you saw the ink applied by Hancock or the impasto shaped by the hand of vanGogh himself. If historical documents or great works of art don’t interest you, then perhaps you value antiques. You may grow sentimental when you use a cedar chest constructed by your greatgrandfather – the chest that has held the clothes and family mementoes of several generations and that will one day be passed along to your children and eventually to your greatgrandchildren. You may instead have sentimental attachment to, say, the narrow gold wedding band that your great-grandfather slid onto your great-grandmother’s finger when they married. You may know that this ring – this piece of gold that has been passed through several generations – will again be used in your wedding to mark the exchange of solemn vows.

Our emotional responses to certain physical objects seem to be tied to our belief that these objects are special things that have persisted things that came into being long ago and continue to exist. Is it true, however, that historical documents, paintings, and hierloomshave persisted? Ink has disappeared, paintings have chipped, antiques have been nicked, and rings have worn thin with time. Given such changes, is it true that the document in the Archives today is the same document that John Hancock signed? Is the thin wedding band in your mother’s jewelry box the same band that your greatgrandmother received on her wedding day?

Complications. Suppose you learn that van Gogh’s painting was restored in the 1970s after it was damaged by vandals. You are told that a restoration specialist patched the canvas and applied layers of paint to match exactly the surrounding impasto. Do you still believe that you have seen the same painting that van Gogh himself produced a century and a half ago?

Suppose that you accidentally drop your great-grandmother’s wedding ring down a storm drain. To console you, your fiancé hires a jeweler to produce an exact replica a qualitatively identical ring with the same inscription, scratches in the same relative locations, etc. In spite of your fiancé’s good intentions, wouldn’t you be justifiably sad and disappointed that you no longer have the same ring that can be traced back ten years to your exchange of wedding vows? Now, suppose instead that you do not lose your great-grandmother’s ring, but learn that when she lost weight as she aged, she had her ring resized a small piece of the gold was removed to make the ring smaller. Then, when your portly grandmother inherited the ring, she paid to have gold added to make the ring larger. Now, is the ring in your mother’s jewelry box the same ring that your great-grandmother received on her wedding day? Is there a ring that has passed through several generations?

[For further thought… Not only does our emotional attachment to objects seem to a function of our beliefs about the persistence of objects, but our emotional attachment to people seem to betray our beliefs about the persistence of people. You may love your best friend, in part, because you believe that he or she is the same person with whom you have shared so many special moments in the past. You grieve profoundly the sudden death of a grandparent when you contemplate the past: you believe that the person who just died is the same person who, years ago, took you on special outings or baked special cakes. Similarly, if a grandmother dies after a prolonged decline with Alzheimer’s, the grief may be less pronounced because, perhaps, one is not as confident that the loved one of so long ago is the same person who just died – a person unable to recognize her husband, her children, or her grandchildren. Consider problems of identity a bit closer to home. Some estimate that the average brain loses 9,000 neurons each day. If so, is your brain the same brain that you had a year ago? A decade ago? Now, what about you? Are you the same person who began high school more than four years ago? Will you be the same person who turns forty more than a decade from now? If Hestevold someday declines with Alzheimer’s, will it be he who can no longer recognize his wife and children? Philosophical inquiry about the persistence of persons is complicated; in “Physics, Metaphysics, & Other Nonsense” let us restrict our inquiry about identity to the persistence of nonliving entities such as pieces of parchment, paint-covered canvasses, cedar chests, rings, and physical particles.]

II.A puzzle involving identity across space

A.Tootsie’s Orchid Lounge & the Mayor of Memphis

A convention of Tennessee mayors has just ended in Nashville, and the mayor of Memphis is parked just outside Tootsie’s Orchid Lounge, a famous bar just below the Ryman Auditorium on lower Broad Street in downtown Nashville. Having had a late supper, themayor decides to take backroads back to Memphis and to drive a couple hours west toward home before spending the night.

If you drive west on Broad Street, Broad becomes West End. If you drive further west, West End becomes Harding Road. Harding Road then forks: Highway 100 runs westward to Linden, and Highway 70 runs westward to Waverly. (Though the Linden route is a bit longer, one can continue west to Memphis from either Linden or Waverly.)

Hwy 70Waverly

Broad St. [BR] West End [WE] Harding Rd [HR]

Tootsie’s Hwy 100 Linden

Orchid Lounge

NORTH

Not wanting to think too hard about how to get back home, the Memphis mayor says aloud, “Here I am parked on lower Broad Street; I’ll just stay on the same road and drive two hours west before stopping for the night.” As luck would have it, the Mayor of Waverly and Mayor of Linden stagger out of Tootsie’s and overhear the Memphis mayor’s declaration about her travel plans. Eager to promote his city, the Waverly major announces, “If you stay on Broad Street for two hours, you’ll end up in the fair city of Waverly for the night!”

With great indignation, the Mayor of Linden retorts, “No! If you stay on Broad Street for two hours, you’ll spend the night in the fairer city of Linden.”

Who is right? If the Memphis mayor starts on Broad Street and drives on the same highway for a couple of hours, will she spend the night in Waverly or Linden? The Waverly mayor tries to tip the scales: “Waverly has a larger population than Linden, and its citizens recently passed a referendum declaring Waverly to be the gateway to west Tennessee.” Does this fact imply that the Memphis major will land in Waverly if she stays on the same road for two hours?

Not to be outdone, the Linden mayor announces, “In a recent study, the Tennessee Department of Transportation announced that there are half as many car accidents on 100 than 70. The Linden Town Council subsequently erected dozens of billboards along Highways 100 and 70, making clear that remaining on Broad from Tootsie’s all the way to Linden is the safe highway into west Tennessee.” Does this fact involving the TDOT study and Town Council imply that the Memphis mayor will spend the night in Linden if she stays on the same road for two hours?

Fearing fisticuffs outside the door of Tootsie’s, the Memphis mayor phones noted metaphysician, Roderick Chisholm to resolve this dispute.

Stop! Before reading further, how would you resolve this problem of identity across space? As a metaphysician, what would you say to the mayors?

B.Roderick Chisholm’s solution.

Below is a paraphrase to Roderick Chisholm’s response to a similar story:[1]

Your fellow-mayors’ dispute has to do with the following eight objects among others: (1) the easternmost stretch of asphalt BR, (2) the piece of asphalt WE, (3) the piece of asphalt HR, (4) the piece of asphalt (70) that lies between the western end of HR and Waverly, and (5) the piece of asphalt (100) that lies between the western end of HR and Linden, (6) a piece of asphalt that begins at Tootsie’s and ends at Waverly, (7) a piece of asphalt that begins at Tootsie’s and ends at Linden, and (8) a Y—shaped piece of asphalt that has Tootsie’s at the end of its handle and Waverly and Linden at the ends of its forks. These objects overlap in various ways, but they are six different things. BR is not identical with WE or with HR; 70 is identical with neither 100 nor BR. Though WE and 100 are both parts of the Yshaped object, neither is identical with the Yshaped object despite their overlap. These eight objects are equally respectable ontologically. No one of them is any less genuine an entity than any of the others.

Now there is no dispute about any observational data. The two mayors have agreed about what it is that is called “Broad,” and they agree that there are stretches of asphalt that are called, respectively, “100” and “70.” There is no argument that BR, WE, HR, 70, and 100 are all parts of a larger Yshaped object. Your dispute, then, has to do with criteria for constituting the same road, or as we may also put it, with criteria for applying the expression ‘x constitutes the same road as does y’. Each mayor should be able to see that the other mayor has correctly applied the criterion that he happens to be using. That is to say, given the criterion that the Mayor of Waverly is using (involving the larger population and citizens’ vote), it would be true to say that if you start on BR and continue on the same road, you will end up in Waverly. And given the Mayor of Linden’s criterion (involving safety and the billboards), it would be true to say that you would end up instead in Linden. It’s just a matter, therefore, of the mayors invoking conflicting criteria. They have different standards for applying such expressions as ‘the same road’ and ‘x constitutes the same road as does y’.

I realize that the Mayor of Waverly may be inclined to say that he has the “right” criterion and that the Mayor of Linden has the “wrong” criterion; and the Mayor of Linden will be disposed to say just the opposite. But think more carefully and try to see just what it is they would be trying to express if they talk that way. For once you see what it is, you can phone other experts in all probability nonphilosophers this time -- and they will settle the dispute for you.

Thus if the Waverly mayor believes that he is using the expression ‘the same road’ the way the majority of people do or the way that the members of the Town Council or some other more select group uses it and if the Waverly mayor believes that the Linden mayor is not using the expression that way, then we can call in the linguists. They can work up questionnaires and conduct surveys and, it may be hoped, you will soon find out who is right. Or perhaps the Linden mayor’s concern is not with the ways in which the majority or members of the Waverly Town Council may happen to use ‘the same road’. The Linden mayor may think only that his way of using ‘the same road’ is the most convenient one. If he thinks, say, that we can boost business in Linden or address highway traffic problems more efficiently by using the expression his way than by using it the way preferred by the Waverly mayor, then business experts, traffic experts, and psychologists should be able to help. Or if one of the majors thinks that his use is the better one for promoting yet some other kind of good, there will be some other expert who will know better than any of us.

Finally, keep in mind that if people had quite different interests from those that any of us now happen to have and if we had been brought up to play some language game very different from this one, there might be no temptation at all to use either of the present criteria. If you were pressed for time and had no interest in driving backloads, you might ignore HR, 70, and 100 altogether, insisting that staying on the same road from Tootsie’s to Memphis involves zigzagging through downtown Nashville to Interstate40, bypassing WE, HR, 70 and 100 altogether.

We can leave the dispute about the road. As a metaphysician, surely, I have little or not interest in the outcome. I hope we can agree that, in this instance, this metaphysician’s advice is fairly reasonable and that there is little more to be said of philosophical interest.

C.Don’t metaphysicians have more important problems to think about?

Though you may find the mayors’ dispute curious, you may also be thinking, “Who cares? At any end of the day, what does it matter whether Chisholm is right, or whether instead one of the two mayors is right about the identity of Broad Street across space?” True, this problem of identity across space is hardly a timeless question of metaphysics. But, by and by, Chisholm’s insight involving identity across space will help you understand certain views involving identity across time. And these views do matter – they matter with respect to emotional attachments that you may or may not have, and they matter with respect to Special Theory of Relativity. Stay tuned…

III.A puzzle involving identity across time: The Ship of Theseus

A.The Ship of Theseus

Consider Chisholm’s formulation of the problem of The Ship of Theseus:[2]

[L]et us imagine a ship -- the Ship of Theseus that was made entirely of wood when it came into being. One day a wooden plank is cast off and replaced by an aluminum one. Since the change is only slight, there is no question as to the survival of the Ship of Theseus. We still have the ship we had before; that is to say, the ship that we have now is identical with the ship we had before. On another day, another wooden plank is cast off and also replaced by an aluminum one. Still the same ship, since, as before, the change is only slight. The changes continue, in a similar way, and finally the Ship of Theseus is made entirely of aluminum. The aluminum ship, one may well argue, is the wooden ship we started with, for the ship we started with survived each particular change, and identity, after all, is transitive [i.e. if x=y and y=z, then x=z].

But what happened to the discarded wooden planks? Consider this possibility, suggested by Thomas Hobbes: ‘If some man had kept the old planks as they were taken out, and by putting them afterwards together in the same order, had again made a ship of them, this, without doubt, had also been the same numerical ship with that which was at the beginning; and so there would have been two ships numerically the same, which is absurd.’[3] Assuming, as perhaps one has no right to do, that each of the wooden planks survived intact throughout these changes, one might well argue that the reassembled wooden ship is the ship we started with. ‘After all, it is made up of the very same parts, standing in the very same relations, whereas that ugly aluminum object doesn’t have a single part in common with our original ship.’