When Should We Question Identity?

The Ship of Theseus Paradox

A version of this article appears in TWISTED LOGIC: Puzzles, Paradoxes, and Big Questions, by Leighton Vaughan Williams. Chapman & Hall/CRC Press. 2024.

PLUTARCH’S PARADOX

The Ship of Theseus Paradox has its roots in ancient Greek philosophy, emerging as a crucial discussion point in understanding identity and change. Originally posed by the philosopher Plutarch, the paradox was used to question whether a ship, which was gradually having all its wooden parts replaced, remained fundamentally the same ship. This paradox was not just a mere intellectual exercise; it was deeply rooted in the Greek exploration of ‘being’ and ‘becoming’, which were crucial themes in their philosophical inquiries. Over time, the Ship of Theseus became a pivotal reference in philosophical discussions about identity, persisting through the centuries as a tool to test the limits of our understanding of continuity and change.

A QUESTION OF IDENTITY

The Ship of Theseus Paradox is central to discussions in philosophy regarding the nature of identity. It presents a compelling challenge to the idea of persistent identity over time, particularly when an object undergoes gradual change.

THE LEGEND

The story of Theseus’s Ship begins with the legendary hero Theseus, who sailed on a ship to the island of Crete to defeat the Minotaur. After his victory, his ship was preserved and displayed in Athens as a symbol of the city’s pride. Over time, the wooden planks of the ship began to decay and were replaced with new ones. Eventually, every original piece of the ship was replaced, leading to the question: Is the ship still the same ship that Theseus sailed on, even though none of its original components remain?

CONTINUITY AND IDENTITY

If an object has all its parts replaced, is it still the same object? If we say that it is the same object, then we must explain why and how it retains its identity despite having none of its original components. Conversely, if we say that it is not the same object, then we must determine at what point it ceased to be the original and became something new.

The question of whether an object remains the same when its parts have been entirely replaced makes us reassess our understanding of what constitutes an object’s identity. Are objects defined by the matter of which they’re composed, their structure, their history, or by a combination of these and maybe other factors?

THE SUBSTANCE VIEW

The Substance View proposes that the identity of an object is tied to the substance or the matter it is made of. According to this perspective, the Ship of Theseus depends on the continuity of the material components that constitute it. When all the original parts of the ship are replaced, the ship loses its original identity and becomes a new object. This view sees the ship’s identity as static, fixed, and dependent on its material constituents.

This interpretation faces challenges when considering gradual transformations, as it becomes difficult to pinpoint the exact moment when the ship’s identity changes. Moreover, this view might struggle to account for the importance of functional and relational aspect of objects. Critics argue that it cannot satisfactorily explain cases where an object’s function and relation to the world remain constant despite material changes.

Recent debates have also brought into question the implications of digital and virtual identities. In a digital era, where replication and modification of virtual entities are commonplace, how does the Ship of Theseus Paradox inform our understanding of digital identity? Does a digital object lose its ‘identity’ when its code is altered or does it transcend traditional notions of materiality?

THE RELATIONAL VIEW

The Relational View focuses on the idea that the identity of an object is grounded in its relationships with other objects and entities.

Supporters of the Relational View argue that the Ship of Theseus retains its identity through its connections to the story of Theseus, its role in the society in which it exists, and the memories and associations that people have with it.

THE BUNDLE THEORY

The Bundle Theory suggests that an object is nothing more than a bundle of its properties—there’s no ‘object’ beyond the collection of its characteristics. Applying this theory to the Ship of Theseus, one might argue that the ship is merely a bundle of its properties such as its shape, size, purpose, and the arrangement of its planks. As these properties change (when the planks are replaced), the ship’s identity changes too. However, if the ship retains its structure, function, and perhaps other properties, it can still be recognised as the ‘same’ ship. This interpretation encourages us to think of objects as collections of properties rather than stable, unchanging entities.

ARTEFACTS

In the context of the Ship of Theseus Paradox and the discussion on identity and change, the restoration of historical artefacts offers a compelling parallel.

Restoration and Identity

The process of restoring historical artefacts often involves repairing or replacing deteriorated components with new materials to preserve the artefact’s appearance, function, or structural integrity. This process raises questions similar to those in the Ship of Theseus: does an artefact maintain its original identity after restoration, especially when significant portions have been replaced or altered?

Authenticity vs. Preservation

The challenge in artefact restoration lies in balancing authenticity with preservation. Authenticity refers to the degree to which an artefact remains unchanged, retaining its original materials and form. On the other hand, preservation might require the introduction of new materials to prevent further decay or to restore an artefact to a former state. At what point does an artefact become a replica rather than an original?

CASE STUDIES

The Sistine Chapel

Consider the restoration of the Sistine Chapel ceiling, where layers of grime and soot were removed to reveal Michelangelo’s original colours. Some critics argued that the vibrant colours revealed by the restoration were inconsistent with Michelangelo’s intentions, suggesting that the restoration had altered the fresco’s identity. Others contended that the restoration brought the artwork closer to its original state, thus preserving its true identity.

The Parthenon

Similarly, the restoration of ancient buildings, like the Parthenon in Athens, involves replacing eroded stones with new material. Critics might question whether the building maintains its original identity after such changes, while proponents argue that restoration helps preserve the structure’s historical and cultural significance. A key issue is whether it is more ‘genuine’ as a ruin bearing the marks of its history or restored to a state believed to be true to its original form.

The Last Supper

“The Last Supper” by Leonardo da Vinci has undergone several restorations over the centuries due to deterioration caused by environmental factors, wartime damage, and previous restoration attempts. Each restoration has presented a dilemma, requiring restorers to decide whether to attempt to revert the mural to its original state (as much as possible) or to stabilise its condition to prevent further degradation.

Critics argue that each layer of restoration moves the painting further from Leonardo’s original vision, potentially altering its identity. They contend that the original materials, brushstrokes, and techniques employed by Da Vinci contribute fundamentally to the painting’s essence and that replacing or significantly altering these elements diminishes the work’s authenticity.

In philosophical terms, the restoration of “The Last Supper” mirrors the Ship of Theseus Paradox by raising questions about continuity and identity over time. If all the original pigment is removed and replaced, is it still the same painting? Or does the essence of the artwork lie in its visual appearance, its historical significance, or the intent behind its creation?

The Bridge at Mostar

Originally built in the 16th century by the Ottomans, the Stari Most stood as a symbol of unity and an architectural marvel, connecting the diverse communities in Mostar across the Neretva River. Its wartime destruction in 1993 became a poignant symbol of cultural and communal fragmentation,

The decision to rebuild the Stari Most was fraught with questions about identity and authenticity. Could a reconstructed bridge, built centuries after the original, serve the same symbolic and functional roles as its predecessor? The reconstruction effort aimed to use original techniques and materials as much as possible, sourcing local stone and employing traditional Ottoman construction methods. This approach sought to preserve the bridge’s historical authenticity and cultural significance, even as it acknowledged the impossibility of an exact physical replica.

The Stari Most’s reconstruction challenges the Ship of Theseus Paradox by asking whether an object—destroyed and subsequently rebuilt with the intent of mirroring the original as closely as possible—retains its identity. This case pushes the paradox further by introducing the element of complete destruction rather than gradual replacement. Is the new bridge the same as the old, despite the interruption of its physical existence? Or does its reconstruction, imbued with the collective memory, effort, and intention to bridge past and present, confer upon it a renewed identity that is both continuous and distinct?

Through its destruction and reconstruction, the Stari Most offers a powerful narrative on the complexities of identity, continuity, and change. It exemplifies how reconstructed heritage can carry forward the essence of the original, serving as a bridge not only in physical space but in time, memory, and meaning, thereby engaging with the philosophical inquiries posed by the Ship of Theseus Paradox in a deeply human context.

VIRTUAL IDENTITIES

Recent debates have also brought into question the implications of digital and virtual identities. In a digital era, where replication and modification of virtual entities are commonplace, how does the Ship of Theseus Paradox inform our understanding of digital identity? Does a digital object lose its ‘identity’ when its code is altered or does it transcend traditional notions of materiality?

Digital Personas

Digital personas are curated representations of ourselves on the internet, shaped by the information we choose to share on social media, forums, and other online platforms. These personas are not static; they evolve as we update our profiles, post new content, and interact with others. This fluidity raises questions akin to those posed by the Ship of Theseus: if a digital persona is constantly changing, at what point does it become fundamentally different from its original incarnation? Moreover, the curated nature of digital personas prompts us to consider which aspects of our identity are essential and which are mutable.

Artificial Intelligence

AI presents a more complex challenge to traditional concepts of identity. Machine learning algorithms allow AI systems to evolve based on new data and experiences, much like humans learn and change over time. This adaptability leads to questions about the continuity of identity: if an AI’s decision-making processes and behaviours change significantly, is it still the ‘same’ AI?

IMPLICATIONS FOR PERSONAL IDENTITY

In terms of personal identity, the Ship of Theseus Paradox intersects significantly with theories of psychological continuity. According to this theory, personal identity is maintained through the continuity of psychological features like memory, personality, and consciousness. If we apply this to the Ship of Theseus, it raises the question: Is identity maintained through physical continuity or through the continuity of function and recognition?

This perspective is particularly relevant in discussions about human development and change. As individuals undergo physical, emotional, and psychological changes throughout life, at what point do they become ‘different’ individuals, if at all? The Ship of Theseus Paradox, thus, serves as a metaphor for exploring the fluidity and resilience of personal identity amidst constant change.

By integrating these aspects, the discussion around the Ship of Theseus Paradox becomes not only more historically grounded and analytically rich but also deeply connected to contemporary and personal contexts.

BROADER IMPLICATIONS

The Ship of Theseus Paradox may provide a useful framework for grappling with emerging ethical and philosophical issues as advancements in technology push the boundaries of what is possible. For instance, questions about the continuity of consciousness and the identity of entities that undergo substantial change arise in fields such as artificial intelligence and human augmentation.

CONCLUSION: CHALLENGING OUR ASSUMPTIONS

The Ship of Theseus Paradox remains an engaging and relevant tool for philosophical inquiry. Its exploration of identity and change continues to resonate with modern audiences. By challenging our assumptions and forcing us to question our understanding of th world, the paradox fulfils a key purpose of any paradox: to provoke thought and inspire exploration.