metaphysics Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...

, A series and B series are two different descriptions of the temporal ordering relation among

event Event may refer to: Gatherings of people * Ceremony, an event of ritual significance, performed on a special occasion * Convention (meeting), a gathering of individuals engaged in some common interest * Event management, the organization of ev ...

s. The two series differ principally in their use of tense to describe the temporal relation between events and the resulting ontological implications regarding time. John McTaggart introduced these terms in 1908, in an argument for the unreality of time. They are now commonly used by contemporary philosophers of time.

History

Metaphysical Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...

debate about temporal orderings reaches back to the ancient Greek philosophers

Heraclitus Heraclitus of Ephesus (; grc-gre, Ἡράκλειτος , "Glory of Hera"; ) was an ancient Greek pre-Socratic philosopher from the city of Ephesus, which was then part of the Persian Empire. Little is known of Heraclitus's life. He wrot ...

and

Parmenides Parmenides of Elea (; grc-gre, Παρμενίδης ὁ Ἐλεάτης; ) was a pre-Socratic Greek philosopher from Elea in Magna Graecia. Parmenides was born in the Greek colony of Elea, from a wealthy and illustrious family. His date ...

. Parmenides thought that

reality Reality is the sum or aggregate of all that is real or existent within a system, as opposed to that which is only imaginary. The term is also used to refer to the ontological status of things, indicating their existence. In physical terms, re ...

is timeless and unchanging. Heraclitus, in contrast, believed that the world is a process of ceaseless change, flux and decay. Reality for Heraclitus is dynamic and

ephemeral Ephemerality (from the Greek word , meaning 'lasting only one day') is the concept of things being transitory, existing only briefly. Academically, the term ephemeral constitutionally describes a diverse assortment of things and experiences, f ...

. Indeed, the world is so fleeting, according to Heraclitus, that it is impossible to step twice into the same river.

McTaggart's series

McTaggart distinguished the ancient conceptions as a set of relations. According to McTaggart, there are two distinct modes in which all events can be ordered in time.

A series

In the first mode, events are ordered as

future The future is the time after the past and present. Its arrival is considered inevitable due to the existence of time and the laws of physics. Due to the apparent nature of reality and the unavoidability of the future, everything that current ...

present The present (or here'' and ''now) is the time that is associated with the events perceived directly and in the first time, not as a recollection (perceived more than once) or a speculation (predicted, hypothesis, uncertain). It is a period of ...

, and past. Futurity and pastness allow of degrees, while the present does not. When we speak of time in this way, we are speaking in terms of a series of positions which run from the remote past through the recent past to the present, and from the present through the near future all the way to the remote future. The essential characteristic of this descriptive modality is that one must think of the ''series of temporal positions'' as being in ''continual transformation'', in the sense that an event is first part of the future, then part of the present, and then past. Moreover, the assertions made according to this modality correspond to the temporal perspective of the person who utters them. This is the A series of temporal events. Although originally McTaggart defined tenses as relational qualities, i.e. qualities that events possess by standing in a certain relations to something outside of time (that does not change its position in time), today it is popularly believed that he treated tenses as monadic properties. Later philosophers have independently inferred that McTaggart must have understood tense as monadic because English tenses are normally expressed by the non-relational singular predicates "is past", "is present" and "is future", as noted by R. D. Ingthorsson.

B series

From a second point of view, events can be ordered according to a different series of temporal positions by way of two-term relations which are asymmetric,

irreflexive In mathematics, a binary relation ''R'' on a set ''X'' is reflexive if it relates every element of ''X'' to itself. An example of a reflexive relation is the relation " is equal to" on the set of real numbers, since every real number is equal ...

and transitive: "earlier than" (or precedes) and "later than" (or follows). An important difference between the two series is that while events continuously change their position in the A series, their position in the B series does not. If an event ever is earlier than some events and later than the rest, it is always earlier than and later than those very events. Furthermore, while events acquire their A series determinations through a relation to something outside of time, their B series determinations hold between the events that constitutes the B series. This is the B series, and the philosophy which says all truths about time can be reduced to B series statements is the B-theory of time.

Distinctions

The

logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from prem ...

and the linguistic expression of the two series are radically different. The A series is ''tensed'' and the B series is ''tenseless''. For example, the assertion "today it is raining" is a tensed assertion because it depends on the temporal perspective—the present—of the person who utters it, while the assertion "It rained on " is tenseless because it does not so depend. From the point of view of their truth-values, the two propositions are identical (both true or both false) if the first assertion is made on . The non-temporal relation of precedence between two events, say "E precedes F", does not change over time (excluding from this discussion the issue of the relativity of temporal order of causally disconnected events in the theory of relativity). On the other hand, the character of being "past, present or future" of the events "E" or "F" does change with time. In the image of McTaggart the passage of time consists in the fact that terms ever further in the future pass into the present...or that the present advances toward terms ever farther in the future. If we assume the first point of view, we speak as if the B series slides along a fixed A series. If we assume the second point of view, we speak as if the A series slides along a fixed B series.

Relation to other ideas in the philosophy of time

There are two principal varieties of the A-theory, presentism and the

growing block universe The growing block universe theory of time (or the growing block view), states that the past and present both exist, and the future as yet does not. The present is an objective property, to be compared with a moving spotlight. By the passage of tim ...

.Presentism and the Space-Time Manifold
by Dean Zimmerman, p. 7 Both assume an objective present, but presentism assumes that only present objects exist, while the growing block universe assumes both present and past objects exist, but not future ones. Views that assume no objective present and are therefore versions of the B-theory include eternalism and

four-dimensionalism In philosophy, four-dimensionalism (also known as the doctrine of temporal parts) is the ontological position that an object's persistence through time is like its extension through space. Thus, an object that exists in time has temporal parts ...

Notes

References

*Craig, William Lane, ''The Tensed Theory of Time'', Springer, 2000. *Craig, William Lane, ''The Tenseless Theory of Time'', Springer, 2010. *Ingthorsson, R. D., "McTaggart's Paradox", Routledge, 2016. *McTaggart, J. E., 'The Unreality of Time', ''Mind'', 1908. *McTaggart, J. E.,''The Nature of Existence'', vols. 1-2, Cambridge University Press, Cambridge, 1968. * Bradley, F. H., ''The Principles of Logic'', Oxford University Press, Oxford, 1922.

External links

Time---Notes on McTaggart and the Unreality of Time
Trinity College Seminar on Time. * {{DEFAULTSORT:A series And B series Philosophy of physics Philosophy of time Concepts in metaphysics