Perdurance

Definition and Core Idea

Perdurance is a technical term in contemporary metaphysics that designates one influential account of how objects persist through time. According to the perdurantist view, an object persists by having different temporal parts (or stages) at different times, much as a spatially extended object has different spatial parts at different locations.

On this view, a person, a tree, or a table is not wholly present at each moment of its existence. Instead, each such entity is a four‑dimensional space–time “worm”, composed of a series of temporal slices or segments. The person you are now is one temporal part; your ten‑year‑old self is another; the whole person is the mereological sum of all those temporal parts.

Perdurance is usually contrasted with endurance, the view that persisting objects are wholly present at each time at which they exist and do not have temporal parts. While both theories aim to make sense of change, identity, and duration, they propose fundamentally different ontological models of persistence.

Historical Background and Philology

In ordinary English, “perdurance” is a relatively rare term meaning lastingness or continued existence. It derives from Late Latin perdurare, “to last or endure throughout,” formed from per- (“through, thoroughly”) and durare (“to last, harden”). Historically, philosophers sometimes used “endure” and “perdure” in more or less ordinary senses, to speak of what continues in being.

The technical sense of “perdurance” as a theory of persistence emerges prominently in 20th‑century analytic metaphysics, especially in work influenced by the development of relativity theory and four‑dimensional models of space–time. While related ideas can be traced to earlier figures (such as discussions of temporal parts in the wake of McTaggart’s analysis of time), the fully systematized perdurantist position is most strongly associated with David Lewis and other proponents of four‑dimensionalism.

In analytic usage, “to perdure” is now a verb of art: an object perdure iff it has temporal parts; it endures iff it is wholly present at each moment of its existence. The English words thus track a metaphysical distinction, not merely a difference in rhetorical style.

Perdurance in Contemporary Metaphysics

Perdurance plays a central role in the metaphysics of persistence, change, and identity over time.

1. Temporal Parts and Four‑Dimensionalism
   Perdurantists maintain that just as an extended object (like a road) is composed of spatial parts (segments of the road), a temporally extended object (like a life) is composed of temporal parts. A temporal part is something that exists only at a particular time (or short temporal interval) and is a part of the larger four‑dimensional whole.

   Under four‑dimensionalism, reality is conceived as a four‑dimensional manifold, and ordinary objects are extended in time in the same ontological sense that they are extended in space. Perdurance is the corresponding account of how such four‑dimensional objects persist: by being spread out in time and composed of temporal slices.

2. David Lewis’s Formulation
   David Lewis is the most influential defender of perdurance. In his work (especially On the Plurality of Worlds and related essays), Lewis:

   • Treats objects as space–time worms made of temporal parts.
   • Explains change by appeal to differing properties of distinct temporal parts: a leaf is first green and later brown because one temporal part is green and another is brown.
   • Connects perdurance with his broader mereological framework, in which parts and wholes (including temporal parts and four‑dimensional wholes) play a central explanatory role.

   For Lewis, to persist by perduring is to exist at different times by having different temporal parts located at those times, each bearing the properties appropriate to that time.

3. Contrasts with Endurance and Exdurance

   • Endurance: Endurantists deny that ordinary objects have temporal parts. A persisting object is wholly present at each moment of its existence; change is explained by the same whole object having different properties at different times.
   • Exdurance (Stage Theory): Some four‑dimensionalists introduce a further contrast: on exdurance (or “stage theory”), what is strictly speaking an object at a time is a momentary stage, and persistence is analyzed in terms of counterpart relations among these stages across time, not by identifying a single worm‑like whole.

   In these debates, perdurance specifically designates the view that persistence consists in having temporal parts united into a single extended whole, not merely related by counterpart relations.

4. Applications
   Perdurance has been applied to a range of metaphysical issues:

   • Material constitution and fission: to analyze cases where objects seem to coincide or split (e.g., a statue and its clay, or a person dividing into two continuers).
   • Personal identity: to account for the persistence of persons across radical psychological or bodily change by treating a person as a four‑dimensional aggregate of person‑stages.
   • Modal and temporal analogies: some perdurantists draw analogies between temporal parts and modal counterparts, integrating theories of time and possibility.

Debates and Objections

Perdurance has been both influential and controversial. Debates typically focus on whether it offers a better explanation of persistence and change than endurance, and whether its ontological commitments are acceptable.

1. Arguments for Perdurance
   Proponents often emphasize:

   • Compatibility with Relativity: The four‑dimensional picture aligns naturally, they argue, with the space–time framework of relativity, in which no single global “present” is privileged.
   • Solution to the Problem of Change: By assigning incompatible properties (e.g., green and brown) to different temporal parts, perdurance promises a clear account of change without violating logical principles like the Law of Non‑Contradiction.
   • Mereological Elegance: For theorists who favor a unified, part–whole ontology, temporal parts provide a systematic way to treat time and space on an ontological par.

2. Objections and Criticisms
   Critics raise several concerns:

   • Intuitiveness and Ordinary Thought: Many contend that our ordinary conception of ourselves and objects is endurantist—we think of the same whole person existing at different times, not of a series of person‑stages. Perdurance is said to “fragment” objects in a way that conflicts with common sense.
   • The “Too Many Parts” Worry: Allowing temporal parts in addition to spatial parts seems to multiply entities dramatically. Some object that this is ontologically profligate and violates parsimonious standards.
   • Identity over Time: Endurantists argue that perdurance may not capture the strict identity we care about in everyday and ethical contexts; critics claim that a space–time worm is a theoretical construct lacking the sort of unity that grounds responsibility or survival.
   • Temporary Intrinsics Problem: While perdurantists present their view as solving the problem of temporary intrinsics (how an object can have different intrinsic properties at different times), some argue that appealing to temporal parts simply relocates the problem, or results in an overly revisionary conception of properties and times.

3. Current Status
   In contemporary analytic metaphysics, perdurance remains one of the major competing views of persistence, often discussed alongside endurance, exdurance, and related hybrid accounts. The term now functions as a standard label within these debates, with many positions defined partly by how they accept, refine, or reject the perdurantist picture.

The choice between perdurance and its rivals is typically framed as a matter of theoretical virtues—such as simplicity, coherence with physics, and alignment with ordinary intuitions—rather than one settled by straightforward empirical evidence. As a result, discussions of perdurance continue to shape broader debates about the ontology of time, the structure of objects, and the nature of identity.