McTaggart Argument Against Time

Overview and Historical Context

The McTaggart Argument Against Time (often called McTaggart’s argument for the unreality of time) is a central and highly debated argument in the philosophy of time. It originates from the British idealist philosopher J. M. E. McTaggart in his 1908 paper The Unreality of Time and later developments in The Nature of Existence.

McTaggart’s conclusion is radical: time is not real. He maintains that the features we take to be essential to time—especially the distinctions between past, present, and future—are ultimately incoherent. Since these dynamic features are, in his view, necessary for time, he infers that time itself cannot exist in reality.

The argument has had enduring influence, shaping the modern distinction between A-theories (tensed, dynamic views) and B-theories (tenseless, static views) of time. It continues to be a focal point in discussions of whether time genuinely “flows” or whether the universe is more like a four-dimensional block in which all events are equally real.

A-Series, B-Series, and the Structure of the Argument

McTaggart introduces two key ways of ordering events in time, now standard in analytic metaphysics:

• The A-series: Events are ordered as past, present, or future, and these tensed properties are constantly changing. What is now future will become present, and then become past.
• The B-series: Events are ordered by earlier-than, later-than, and simultaneous-with relations. For example, the year 2000 is earlier than 2050, and this relation does not change.

McTaggart’s argument unfolds in two major stages.

1. Time requires an A-series.
   He contends that genuine change is essential to time. However, a merely B-series ordering (earlier/later) is, he argues, static: the fact that one event is earlier than another never changes. To get real change, events must gain and lose the properties of being future, present, and past. This dynamic feature belongs only to the A-series.
   Therefore, if there is time, there must be a real A-series.

2. The A-series is contradictory.
   McTaggart then argues that the A-series itself is incoherent. Every event, he claims, is future, then present, then past. But being future, present, and past are mutually exclusive properties. This appears to generate a contradiction: one and the same event seems to have incompatible A-properties.

From these steps, McTaggart concludes that time (which requires a coherent A-series) cannot exist. The remainder of the argument attempts to show that this contradiction cannot be harmlessly explained away as simply “change over time,” because that explanation, he argues, triggers an infinite regress.

Infinite Regress and Alleged Contradiction

The core of the infinite regress problem arises when one tries to resolve the apparent contradiction by saying:

• An event is future, then is present, then is past—but not all at once.

To make this precise, one typically says something like:

• Event E is future at time t₁, present at time t₂, and past at time t₃.

McTaggart’s response is that this move reintroduces the same problem at a higher level:

1. To say E is future at t₁, present at t₂, and past at t₃, one must treat t₁, t₂, and t₃ themselves as standing in A-series relations: each of these times is in its turn future, then present, then past.
2. This means that the times at which E is future, present, and past themselves must be characterized as future, present, and past at other times.
3. That generates a second-order A-series about the times that describe E’s first-order A-properties.
4. Applying the same reasoning again, this second-order A-series requires a third-order A-series, and so on without end.

McTaggart concludes that we encounter an infinite regress of A-series needed to explain how events can be successively future, present, and past without contradiction. Because the regress is supposed to be explanatory but never completed, it is treated as vicious (i.e., undermining the coherence of the very idea it was meant to save).

Thus, according to McTaggart:

• If we say events have all three A-properties, we get a contradiction (incompatible properties).
• If we say they have them at different times, we trigger an infinite regress that never properly explains the original problem.

From this, he infers that the A-series is incoherent, and since time requires the A-series, time is unreal.

Responses and Ongoing Debates

Philosophers have reacted to McTaggart’s argument in diverse ways, typically contesting either (a) his first claim that time requires the A-series or (b) his second claim that the A-series is incoherent.

1. B-theorist responses (denying the necessity of the A-series)
   B-theorists accept McTaggart’s critique of the A-series but reject his first step:

   • They argue that change can be explained purely in B-series terms: an object’s properties vary across earlier/later times, without any objective “presentness”.
   • On this view, tense is a feature of language or perspective rather than of reality itself. “Now” works like “here”: it picks out a reference point but does not mark a metaphysically special time. For such theorists, McTaggart’s conclusion that there is no A-series supports tenseless or block universe models of time, rather than full-blown unreality of time.

2. A-theorist responses (defending the A-series)
   A-theorists maintain that the distinctions of past–present–future are real and irreducible, and many try to show that McTaggart’s alleged contradiction is avoidable:

   • Some argue that events do not simultaneously possess the properties of being past, present, and future; rather, they possess them successively, and the description of this succession does not require a further A-series in a problematic way.
   • Others revise the understanding of A-properties, treating them as relational or indexical in carefully formulated ways, hoping to avoid the infinite regress or the claim of inconsistency.
   • Still others contend that McTaggart mischaracterizes the logical form of tensed statements, and that once the logic of tense is properly understood (e.g., through tense logic or temporal semantics), the contradiction disappears.

3. Critiques of the regress itself
   Some philosophers question whether the regress is truly vicious:

   • They suggest that higher-order temporal attributions can be truncated or treated as harmless, analogous to other infinite structures that do not undermine coherence (such as infinite divisibility in mathematics).
   • Others maintain that one need not posit an endlessly nested hierarchy of A-series to make sense of change; instead, ordinary tensed discourse already captures what is needed without the metaphysical burden McTaggart claims.

4. Impact on contemporary metaphysics and physics
   McTaggart’s argument continues to inform:

   • Debates between presentism, eternalism, and growing block views of time.
   • Interpretations of the apparent “block-like” nature of spacetime in relativity theory, and whether physical time supports an A-series or merely a B-series description.

Overall, the McTaggart Argument Against Time remains a cornerstone in the philosophy of time. It functions less as a settled refutation of time’s reality and more as a powerful challenge: any adequate theory of time must explain either how the A-series is coherent or how time and change can be fully understood without it. The lack of consensus keeps the argument at the center of ongoing metaphysical discussion.