Metaphysics of Time

Gleaned from Natalja Deng, God and Time (Cambridge University Press, 2019) in the Elements in the Philosophy of Religion series edited by Yujin Nagasawa.

In contemporary metaphysics A-theorists argue for a dynamic (tensed) theory of time and B-theorists argue for a static (tenseless) theory of time in which time is much like space.

Among A-theorists are, e.g., 

(i) those who believe only the present exists, 

(ii) those who believe that reality is a growing block because the past as well as present time exist, and 

(iii) those who believe that all times exist but that only one of them is ever absolutely present.

B-theorists believe that all times exist but that each time is present only “relative to itself” with no ontological privilege.

“The overall shape of the A versus B dialectic is that the A-theory is often seen as capturing the way we ordinarily think about and experience time, while the B-theory is seen as being closer to the results of modern physics.”

“There are three major metaphysical theories about what how things persist. The first is endurantism. This is the view that things persist by surviving from one time to the next, where this survival amounts to strict numerical identity.”

“Perdurantism is the view that things persist over time by being spread out or extended over it. According to perdurantists, things persist by having not only spatial parts, but also temporal parts (or stages). So, material objects are temporally extended. They are four-dimensional, in the sense that they are spread out in time – the fourth dimension – just like they are spread out in the three spatial dimensions.”

“Endurantism is the view that things persist by being wholly present at each time they exist, where to be wholly present at a time is, roughly, to have all of one’s parts exist at that time... Perdurantists have to be four-dimensionalists, since they think objects persist by having temporal parts (and at least some objects do persist). But there are ways of being a four-dimensionalist without accepting perdurantism.”

“some four-dimensionalists reject perdurantism and accept the stage view (also known as exdurantism) ... This is the third of the three main views of persistence ... on the stage view, it is the stages that persist over time, and that we refer to when we refer to ordinary objects. When someone uses your name, they refer to a stage. Which stage they refer to depends on when they use the name.”

See also Ned Markosian's entry on Time in the Stanford Encyclopedia of Philosophy and Heather Dyke's entry on Time, metaphysics of in the Routledge Encyclopedia of Philosophy.