 | This article needs additional citations for verification. (June 2015) |
In metaphysics, the A series and the B series are two different descriptions of the temporal ordering relation among events. 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.