The two series differ principally in their use of tense to describe the temporal relation between events and the resulting ontological implications regarding time.
Metaphysical debate about temporal orderings reaches back to the ancient Greek philosophers Heraclitus and Parmenides.
[further explanation needed] Heraclitus, in contrast, believed that the world is a process of ceaseless change, flux and decay.
Although originally McTaggart defined tenses as relational qualities, i.e. qualities that events possess by standing in a certain relation to something outside of time (that does not change its position in time),[1] today it is popularly believed that he treated tenses as monadic properties.
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 10 February 2025.
Views that assume no objective present and are therefore versions of the B-theory include eternalism and four-dimensionalism.
Vincent Conitzer argues that A-theory is related to Benj Hellie's vertiginous question and Caspar Hare's ideas of egocentric presentism and perspectival realism.