Theories of Time

Overview

• Discussion of four main theories of time.
• Each theory involves three sub-theories or components.

Components of a Theory of Time

1. Temporal Ontology

   • Defines which times exist (past, present, future).
   • Questions if an object's position in time determines its existence.

2. A Theory vs. B Theory

   • A Theory: Time is structured by relations like earlier than and later than, with a real distinction between past, present, and future.
   • B Theory: Time does not intrinsically have properties like past, present, and future; these are perspectival.

3. Temporal Passage

   • Determines whether time passes and if change is real.
   • Static theories see no real passage; dynamic theories see change as fundamental.

Presentism

• Temporal Ontology: Only present events exist.
• A Theory: Distinction between past, present, future is real.
• Temporal Passage: Dynamic change view; what exists changes with time.
  • Illustrated with a 4D block model where a vertical plane represents present events.

Growing Block Theory

• Temporal Ontology: Past and present events exist; future events do not.
• A Theory: Real distinction between past, present, future.
• Temporal Passage: Reality is dynamic, adding to the universe over time.
  • Visualized as a block growing with time.
  • Implication: You exist not just now, but also in the past.

Eternalism

• Temporal Ontology: All events (past, present, future) exist eternally.
• B Theory: Past, present, future are perspectival, not intrinsic to time.
• Temporal Passage: Time does not truly pass; universe is static.
  • All events exist within a 4D space-time model.

Moving Spotlight Theory

• Temporal Ontology: Similar to eternalism; all events exist.
• A Theory: Real properties of past, present, future.
• Temporal Passage: Property change dynamic theory.
  • Property of being present moves over events like a spotlight.
  • Reality is dynamic in terms of which events are "lit up" as present.