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The relationship between identity and change in the philosophical field of metaphysics seems, at first glance, deceptively simple, and belies the complexity of the issues involved. This article explores "the problem of change and identity".

Change[link]

When an object changes, it always changes in some particular way. A baby grows up, and so changes in respect of size and maturity; a snake sheds its skin, and so changes in respect of its skin. "Change" may therefore be defined as follows:

An object, O, changes with respect to property, P, if and only if O has P at one time, and at a later time, O does not have P.

That seems to be, in one way, what it means for a thing to change: it has a property at one time, and later it does not have that property. If a banana becomes brown, it can then be said: at one time, the banana is yellow; several days later, the banana is not yellow, but is instead brown. This appears fairly straightforward at this point, and there are no apparent problems as yet.

Another way for an object to change is to change its parts.

An object, O, changes with respect to its part, P, if and only if O has the part P at one time, and at a later time, O does not have P.

Some philosophers believe that an object can't persist through a change of parts. They defend mereological essentialism.^[1]

Problem of change[link]

The question then arises as to what sort of change happens after a thing is destroyed? When a person dies, one does not say that the person's life has changed. Neither does one go around saying, "Harry just isn't the same sort of guy since he died." Instead, one says that Harry's life has ended. Similarly, when a building is demolished, one does not say that the building 'changes'; one says that it is destroyed. So what sort of events, on the one hand, result in a mere change, and what sort of events, on the other hand, result in a thing's destruction — in the state of its existence? This is one aspect of the problem that will be considered here. It is called "the problem of change and identity".

The Ship of Theseus[link]

The "problem of change and identity" is generally explained with the story of the Ship of Theseus:

In ancient times, there was a ship, called the "Theseus" after its famous former owner. As the years wore on, the Theseus started getting weak and creaky. The old boards were removed, put into a warehouse, and replaced with new ones. Then, the masts started tottering, and soon they, too, were warehoused and replaced. And in this way, after fifty years, this ship now has all new boards, masts, and everything. The question then arises: Is the ship in the harbor, now called S2, the same ship as the ship that was in the harbor, fifty years ago (called S1, for convenience)? In other words, is S2 really the "Theseus"?

There is one answer which is a little too easy and quick. One might say: "No, of course not. The Theseus has changed a lot, so it's not the same ship. At the end of your life, you're not going to be the same person as you were, when you were a teenager. You're going to change a lot in the meantime." However, this is not quite answering the intended question. What is intended by the question is the sense of the word, "same", in which an old woman is the same person at the end of her life as she is, at the beginning of her life. Certainly, the word, "same", has such a sense. After all, one implicitly depends on it when one says, for example, "She has changed a lot". In order for someone to change a lot, there has to be one person who underwent the change. (One could perhaps reject that sense, saying that objects do not change over time.)

Going back to the definition of "change", an object changes with respect to a property if the object has that property at one time, and at a later time, the object does not have the property. What changes is the fact that the object has a particular property. The only way that that fact can change is if the object remains in existence. One can therefore think of a continuing object as the ground of change, or the arena where change occurs, as it were. To get back to the Theseus, the question is: Has the Theseus merely changed a lot, or is the Theseus gone, being replaced by a new ship?

One may say, "Sure, it's just a refurbished Theseus, greatly changed to be sure, but still the Theseus". If one thinks in this manner, then consider what happens when the story is extended further. Suppose someone buys all the planks, masts and whatever that is stored in the warehouse, and out of all of those materials, and absolutely no others, he builds a ship according to the same plans that were used to build the ship, christened "the Theseus". And this ship, called S3, is launched and sits on the other side of the harbor where S2 is. Is S3 the same as S1? In other words, is this recently-constructed ship, the same ship as the ship originally called the "Theseus", considering that S3 was built out of the same materials, and according to the same plans as S1.

One could take this concept even further by not only the properties but also its subject matter of the "ship". What if instead the warehoused planks, masts, and other materials were used to build something completely different from a ship, like a house. (A concept explored by the artist Simon Starling, who turned a shed into a working boat and then back into a shed, winning him the 2005 Turner Prize.) The same materials and supplies are being used; yet they have taken on a new form. This relates to the concept of recreation vs. destruction.

Inevitably, the problem arises: How can one ever say that both S2 and S3 are the same ship as S1, the original Theseus? This is because if they were both the same as S1, then they would have to be the same as each other. This follows from transitivity, which states that if x = y and x = z, then y = z. With S2 and S3 being clearly different ships, sitting on opposite sides of the harbor, three choices present themselves:

• S2 is the same ship as S1;
• S3 is the same ship as S1; or
• neither is the same ship as S1, and S1 has ceased to exist.

How does one then decide which is the correct answer in this case? It is difficult to tell. Whenever one makes an identity claim (i.e. a claim which states that two things are the same), one almost always uses two different descriptions. Sometimes, one may say, "x = x", like "I am I", but such claims are not particularly interesting or informative. The interesting identity claims are claims where two different descriptions are used for one and the same thing. As an example, take these two descriptions: "the Morning Star", and "the Evening Star". Sometimes, one can look in the sky just before dawn, and see a very bright point of light — that has been called "the Morning Star". And then also, one can look in the sky just after sunset, and see a very similar point — that has been called "the Evening Star". The Morning Star is, in fact, identical to the Evening Star — both are the planet Venus. As such, they are "two" things, only in description, but in actuality, are one and the same thing under two different descriptions.

It is a similar case with S1, S2, and S3, those being three different abbreviations, standing for the following descriptions:

• "S1", referring to the ship which sat in the harbor fifty years ago, newly christened "the Theseus";
• "S2", referring to the ship which sits in the harbor now, with the new planks; and
• "S3", referring to the ship which sits in the harbor, recently constructed out of the old planks.

When one, therefore, asks a question like, "Is S2 the same as S1?", one can be understood to mean this: "Is the ship which sits in the harbor now, with the new planks, the same ship as the ship which sat in the harbor fifty years ago, newly christened "the Theseus"?" Do those two descriptions refer to the same thing, or do they not?

Philosophers are not interested in the "Ship of Theseus" problem per se, but to a more basic problem which is this: How does one decide that X is the same as Y, where X describes something at one time, and Y describes another thing at a later time? This is called the "problem of identity over time", or alternatively, the "problem of change".

Leibniz's solution[link]

The German philosopher, Gottfried Leibniz, came up with what is now called Leibniz's law (see Identity of indiscernibles) that may have some bearing on the question. Leibniz's law states:

X is the same as Y if, and only if, X and Y have all the same properties and relations; thus, whatever is true of X is also true of Y, and vice-versa.

Applying Leibniz's Law to the Ship of Theseus problem, S2 is the same as S1 if, and only if, S2 and S1 have all the same properties and relations. Does the ship now in the harbor have all the same properties and relations as the ship that was in the harbor fifty years ago? One might be tempted to say, "Clearly not! They have lots of different properties. So they can't be the same ship." Does that sound convincing? To answer this question, let us consider the property, "contains mast #1". Mast #1 is one of the masts that the original Ship of Theseus had. S1 definitely had this property, but S2 is not so equipped, but has mast #2, instead. It follows that S2 must therefore be different from S1.

Many philosophers strongly oppose this view. For if this argument works, then any property that has changed from the last time we looked at a thing would mean that the thing does not exist anymore, and there is a new thing in its place. Every little change in every little property would mean the whole thing is destroyed. Suppose we look at S1 just a couple of years after it was built. If just one plank has been replaced, will we say that the ship is a different ship? Many philosophers would say surely not, as would common sense. But the ship that is floating on the ocean for a couple of years does have different properties from the original. Leibniz's Law would have us say that it is a different ship. One might see all this and conclude, "Well, Leibniz's Law must not be a law at all, but a false claim! X and Y do not need to have all the same properties to be the same thing."

Leibniz's Law can be saved, by saying: Properties are to be described as occurring at particular times, i.e. they are indexed to times. A property that is described as at a particular time is said to be "temporally-indexed". For example, we can say that S1 has mast #1 in 600 BC. If we say what time the ship has the mast, then we have indexed the property of having the mast to that time. We say the ship has the mast then, using the word, "has", tenselessly. That means we do not say that it, at present, has the mast, but rather, we say it "has" the mast in 600 BC. We are not claiming that the ship has the mast at any other time; just at that time. But if it were a later time, say 550 BC, that very same ship could "have" mast #1 in 600 BC, considering that we are talking about a tenseless "have". That is, it always has the same properties, but the properties are of the form P-at-T. This gives us a way to save Leibniz's Law from the objection we gave, but at the same time, brings up the issue of whether change really occurs. After all, we defined "change" as something having one property at one time, and not at some later time. By this solution though, any given object always has all the properties throughout time, and the properties are merely temporally-specific.

Putting this in plain English, S1 now has the property that it will have mast #2; and S2 now has the property that it did have mast #1. We can then say that S1 and S2 have all the same temporally-indexed properties. According to Leibniz's Law, therefore, they would be the same ship.

One might also say, through the same sorts of contortions that S1 and S3 might have the same temporally-indexed properties. It then follows from Leibniz's Law that they instead would be the same ship.

Can Leibniz's Law help us decide whether it is S2 or S3 that is the same as the original Theseus? Perhaps not by itself. Leibniz's Law says that some ships are the same, just in case, they have all the same properties and relations — or, rather, the same temporally-indexed properties and relations. How then is one to decide that they have all the same temporally-indexed properties and relations? Leibniz's Law seems to offer little or no help when it comes to that decision.

Pragmatic solution[link]

One popular solution to the problem of the Ship of Theseus is to say that the meaning of "same" depends on what purpose the word is being used for. If, supposing it turns out that the original Ship of Theseus, S1, was actually stolen property, and the rightful owner demands its return, should the police give him S2 or S3? Instead of figuring out which ship, if either, is the "same", and then declaring that it should be returned, the pragmatic solution is to figure out which ship should be returned, and then declare that it is the "same". The current owner of S2 could argue that the original owner did not pay for any of the labor or materials of S2, but did provide at least the materials for S3. Thus, the original owner should not be entitled to S2, but rather, some or all of S3. For the purpose of legal entitlement, therefore, part or all of S3 is the same as S1.

Now, let us say that the purpose is not legal entitlement, but rather, the following situation: The admiral of the fleet believes that captains and crews who have fought alongside each other are more effective than captains and crews who are strangers to each other. The admiral then declares that captains must serve at least one year on the same ship. One day, Captain Hercules takes command of the Theseus, and then transfers 18 months later. During this time, the ship's materials are completely replaced as in the previous example, but the crew stays the same. Is S2 = S1, S3 = S1, both, or neither? For the admiral's purpose, S2 = S1 because S2 has the same crew as S1, and Captain Hercules has thus fulfilled the admiral's objective.

Thus, whether S2, S3, both, or neither is the same ship as S1 is a matter of convention and what purposes we have for considering things to be the same or different. Two objects may be considered the same for one purpose, and yet different for another. Is a watch, received as a gift, still the same after it hits the chain saw? For the purpose of returning it, no. But it will always have that same sentimental value. See pragmatism.

The ship of Theseus problem: a non-receivable question[link]

One way of thinking about the Ship of Theseus problem is as follows: It is a question that is not receivable because of the mismatch between the domain of the question and the domain of the subject matter it is applied to. Let us review the three main knowledge domains of concern here:

• A, the real ontological universe that exists and happens by itself;
• B, our reality or how we experience the real universe, A; and
• C, or our scientific analysis of our reality, B.

The distinction between B and C is demonstrated in the following example: In the evening, one can go out and see at the same moment the sun setting, the moon and a few stars; this is our reality or B. In the scientific domain C, however, the analysis of B reveals that the stars are thousands of light years away, the sun is eight light minutes away, and the moon is about a light second away. Since one cannot logically consider these subjects to be both "at the same moment" and "away in time", an exclusive choice has to be made that defines these two separate domains, B and C. Our reality or domain B is created by the complex, but consistent transformation of A by our biological and mental makeup. Therefore, domain B, or our reality, is internally logical. The scientific knowledge, or domain C, is created by the application of a consistent methodology of analysis of our reality, B. Therefore, the scientific domain is internally logical. Domains B and C each have their own internal logic, derived from a consistent approach respecting both processes and subject matter. Using the questions or processes of one domain on the subject matter of another domain will logically produce puzzles, paradoxes, and inconsistencies. The Ship of Theseus problem is an example of such an inconsistency created by the use of the question of identity proper to the ontology of domain A, applied to the subject matter of domain B, our reality. The question about the identity of the Ship of Theseus is simply not receivable and comes from the poor practice of not respecting the proper correspondence of the question domain to the subject matter domain. The problem of identity is an ontological problem, and should therefore be applied to the (metaphysical) subject matter of domain A, the real universe.

Persistence over time[link]

Common-sense tells us that objects persist across time, that there is some sense in which you are the same person you were yesterday, in which the oak is the same as the acorn, in which you perhaps even can step into the same river twice. Philosophers have developed two rival theories for how this happens, called endurantism and perdurantism. Broadly speaking, endurantists hold that a whole object exists at each moment of its history, and the same object exists at each moment, while perdurantists believe that objects are 4-dimensional entities made up of a series of temporal parts like the frames of a movie.

Identity and change in conscious beings[link]

The problem of personal identity relates to change as applied to people. The molecules that make up each individual change almost completely over a period of years. Usually, there is no trouble in saying that a little girl in 1920, for example, is the same as an old woman in 1998, even though they share a relatively small number of molecules in common. The same person is just described in two different ways, first as a little girl, and second, as an old woman. In fact, we are confident enough of our ability to reidentify people over time that we are given names that are supposed to last us from when we get them until we die many years later. The question is exactly why we call the old woman in 1998 the same person as that little girl in 1920.

However, according to quantum physics, individual molecules (and atoms, electrons, protons etc.) have no identity. For example, every electron is the same and in quantum mechanics, one can not keep track of an individual electron precisely. Therefore any electron can interchange with another one with no observable physical change of the system at all. Thus, any real object cannot remain the same, also because of movement of its physical parts (even much bigger than molecules). Similarly to Leibniz solution, in a real life, we can say the person (or any macroscopic object) is the same, because all signs refer to the person (or object) in the past, which evolved in time.

See also[link]

• Ship of Theseus
• Perdurantism

References[link]

External links[link]

• Stanford Encyclopedia of Philosophy on temporal parts
• Carsten Korfmacher, 'Personal Identity', in "The Internet Encyclopedia of Philosophy"
• Identity Change

Manuel Castells in 2009

Manuel Castells (Spanish name: Manuel Castells Oliván, born in Hellín, Albacete, Spain, in 1942) is a sociologist especially associated with information society and communication research.

The 2000–09 research survey of the Social Sciences Citation Index ranks him as the world’s fifth most-cited social science scholar, and the foremost-cited communication scholar.^[1]

Life[link]

Manuel Castells was raised primarily in Barcelona. Although from a conservative family, he was politically active in the student anti-Franco movement, an adolescent political activism that forced him to flee Spain for France. In Paris, at the age of twenty, he completed his degree studies, then progressed to the University of Paris, where he earned a doctorate in sociology. At the age of twenty-four, Dr Castells became an instructor at the University of Paris, from 1967 to 1979; first at the Paris X University Nanterre, who fired him because of the 1968 student protests, then at the École des Hautes Études en Sciences Sociales, from 1970 to 1979.

Subsequently in 1979, in the US, the University of California, Berkeley appointed him to two professorships; Professor of Sociology, and Professor of City and Regional Planning. In 2001, he was a research professor at the Open University of Catalonia (UOC), Barcelona. In 2003, he joined the University of Southern California (USC) Annenberg School for Communication, as a Professor of Communication and the first Wallis Annenberg-endowed Chair of Communication and Technology^[2]. Castells is a founding member of the USC Center on Public Diplomacy, and a senior member of the diplomacy center's Faculty Advisory Council; and is a member of the Annenberg Research Network on International Communication. Castells divides his residence between Spain and the US; he is married to Emma Kiselyova. Since 2008 he has been a member of the governing board of the European Institute of Innovation and Technology.

Theory[link]

The sociological work of Manuel Castells Oliván synthesises empirical research literature with combinations of urban sociology, organization studies, internet studies, social movements, sociology of culture, and political economy. About the origins of the network society, he posits that changes to the network form of enterprise predate the electronic internet technologies (usually) associated with network organization forms (cf. Castells and Organization Theory). Moreover, he coined the (academic) term “The Fourth World”, denoting the sub-population(s) socially excluded from the global society; usual usage denotes the nomadic, pastoral, and hunter-gatherer ways of life beyond the contemporary industrial society norm.

In the 1970s, following the path of Alain Touraine (his intellectual father),^[3] Castells was a key developer of the variety of Marxist urban sociology that emphasises the role of social movements in the conflictive transformation of the city, (cf. post-industrial society).^[4] He introduced the concept of "collective consumption" (public transport, public housing, etc) comprehending a wide range of social struggles — displaced from the economic stratum to the political stratum via state intervention. Transcending Marxist strictures in the early 1980s, he concentrated upon the role of new technologies in the restructuring of an economy. In 1989, he introduced the concept of the "space of flows", the material and immaterial components of global information networks used for the real-time, long-distance co-ordination of the economy. In the 1990s, he combined his two research strands in The Information Age: Economy, Society and Culture, published as a trilogy, The Rise of the Network Society (1996), The Power of Identity (1997), and End of Millennium (1998); two years later, its worldwide, favourable critical acceptance in university seminars, prompted publication of a second (2000) edition that is 40 per cent different from the first (1996) edition.^[5]

The Information Age: Economy, Society and Culture comprehends three sociological dimensions — production, power, and experience — stressing that the organisation of the economy, of the state and its institutions, and the ways that people create meaning in their lives through collective action, are irreducible sources of social dynamics — that must be understood as both discrete and inter-related entities. Moreover, he became an established cybernetic culture theoretician with his Internet development analysis stressing the roles of the state (military and academic), social movements (computer hackers and social activists), and business, in shaping the economic infrastructure according to their (conflicting) interests. The Information Age trilogy is his précis: "Our societies are increasingly structured around the bipolar opposition of the Net and the Self";^[6] the “Net” denotes the network organisations replacing vertically integrated hierarchies as the dominant form of social organization, the Self denotes the practices a person uses in reaffirming social identity and meaning in a continually changing cultural landscape.

Publications[link]

Manuel Castells Oliván is one of the world's most often-cited social science and communications scholars;^[7][8] he has written more than twenty books, including:

• The Urban Question. A Marxist Approach (Alan Sheridan, translator). London, Edward Arnold (1977) (Original publication in French, 1972)
• City, Class and Power. London; New York, MacMillan; St. Martins Press (1978)
• The Economic Crisis and American Society. Princeton, NJ, Princeton UP (1980)
• The City and the Grassroots: A Cross-cultural Theory of Urban Social Movements. Berkeley: University of California Press (1983)
• The Informational City: Information Technology, Economic Restructuring, and the Urban Regional Process. Oxford, UK; Cambridge, MA: Blackwell (1989)
• The Information Age trilogy:

1. Castells, Manuel (1996, second edition, 2000). The Rise of the Network Society, The Information Age: Economy, Society and Culture Vol. I. Cambridge, MA; Oxford, UK: Blackwell. ISBN 978-0-631-22140-1. 
2. Castells, Manuel (1997, second edition, 2004). The Power of Identity, The Information Age: Economy, Society and Culture Vol. II. Cambridge, MA; Oxford, UK: Blackwell. ISBN 978-1-4051-0713-6. 
3. Castells, Manuel (1998, second edition, 2000). End of Millennium, The Information Age: Economy, Society and Culture Vol. III. Cambridge, MA; Oxford, UK: Blackwell. ISBN 978-0-631-22139-5. 

• The Internet Galaxy, Reflections on the Internet, Business and Society. Oxford, Oxford University Press (2001)
• The Information Society and the Welfare State: The Finnish Model. Oxford UP, Oxford (2002) (co-author, Pekka Himanen )
• The Network Society: A Cross-Cultural Perspective. Cheltenham, UK; Northampton, MA, Edward Elgar (2004), (editor and co-author), ISBN 978-1-84542-435-0.
• The Network Society: From Knowledge to Policy. Washington, DC, Center for Transatlantic Relations (2006) (co-editor)
• Mobile Communication and Society: A Global Perspective. Cambridge, MA, MIT Press (2006) (co-author)
• Epilogue of Pekka Himanen's The Hacker Ethic.
• Castells, Manuel (2009,). Communication power. Oxford/New York: Oxford University Press. pp. 608. ISBN 978-0-19-956704-1. 

Recent Journal Articles

• Arsenault, A & Castells, M. (2008) Switching power: Rupert Murdoch and the global business of media politics: A sociological analysis. International Sociology 23(4): 488.
• Arsenault, A, and Castells, M. 2008. The structure and dynamics of global multimedia business networks. International Journal of Communication 2707-48.
• Castells, M (2007) Communication, power and counter-power in the network society. International Journal of Communication 1(1): 238-66.

Pertinent papers

• Social Uses of Wireless Communications: The Mobile Information Society, co-author of the paper for the International Workshop on Wireless Communication Policies and Prospects: A Global Perspective, USC, 8–9 October 2004.

Books about Manuel Castells

• Susser, Ida. The Castells Reader on Cities and Social Theory. Oxford, Blackwell (2002)
• Castells, Manuel; Ince, Martin. Conversations with Manuel Castells. Oxford, Polity Press (2003)
• Stalder, Felix. Manuel Castells and the Theory of the Network Society. Oxford, Polity Press (2006)

References[link]

External resources[link]

• Webpage of Castells at USC Annenberg
• Webpage of Castells at UC Berkeley (Professor Emeritus listing)
• Website devoted to his work, made by Open University of Catalonia

• A scholarly review of the Information Age trilogy
• Video stream of an hour long interview with Castells, conducted in 2001
• International Journal of Communication Academic journal co-edited by Castells, established in 2007
• Manuel Castells' World of Communication, a Manuel Castells exclusive monthly article in Media Coolhunting.
• Audio: Manuel Castells in conversation on the BBC World Service discussion programme The Forum
• Video Stream: Manuel Castells October 2009 keynote at University of Oxford Internet Institute for the release of his new book, "Communication Power"
• Video Stream: Manuel Castells March 2010 at USC Annenberg, International Seminar on Network Theory