In this post, I’ll attempt to explain the basics of two major theories of time and some implications. They are called, perhaps unimaginatively, the A-theory and the B-theory of time. Currently, the B-theory is the most popular view, and so we shall explore this first.
The B-theory of time is also called the “static” theory of time. This is because time is not literally moving; things are not really coming into and going out of existence, as it may seem. The most common version of this theory is the theory of four-dimensional spacetime. This spacetime forms a block, along which lie a great many points. Any event that happens in time, then, can be located or indexed to a particular point in spacetime (this, along with the flux capacitor, is what makes time travel possible). While once regarded as a heuristic, it is now taken to be the sober truth by most popular understandings of physics. Early Einstein, for example, did not believe in the literal truth of spacetime. However, it has been propounded enough that most people believe that time is as much of a physical entity as is space (in fact, they are bound together in a spacetime block!). This theory is also referred to as the “tenseless” theory of time, since tensed language is not literal, but instead stands for the particular indexed point along spacetime. For an example, if I say “I will go to the store in one hour,” and it is now 2 pm on Saturday, I am really saying, “I go to the store at 3pm on Saturday” (it’s actually much more specific than this); the idea is that our language is a simpler way of communicating a complex, and more specific, truth.
The A-theory of time is also called the “dynamic” theory of time. This is because time really is moving; things are really changing; things are really coming into and going out of existence, just as it seems. On this view, there really is such a thing as an objective “now” (whereas there is not on B-theory). On this view, there is not really any such thing as the spacetime block. Events are not spatiotemporally indexed to particular points along the block. Instead, an event (such as, say, Washington’s becoming the first U.S. president) comes into being during a particular moment and then passes out of being once the object of the event no longer exists (in this case, the “becoming”; there was a moment when Washington was not the president; the next moment, he is becoming the president; a moment later, he simply is the president, or he had become the president). This theory is also referred to as the “tensed” theory of time, since tensed language is literally describing the truth of the matter. Many people believe that the A-theory implies the truth of presentism, the teaching that only the present moment exists.
There are advantages that A-theory has over B-theory, and I’d like to list/talk about a few of them:
1. It takes our tensed language seriously.
This one might be quite big. It’s a tall order to suggest that all of our sentences using tensed language are literally false. Further, it accords with our intuition that there really is a “right now” to talk about. Speaking of which:
2. It allows us to use “now” for necessary language.
The tensed theory gives us important information, such as “Your flight is leaving now!” The tenseless theory can give us information, such as “Your flight is leaving at 4pm,” but it cannot communicate to you that it is now 4 pm. In fact, while you can look at a clock and all of that good stuff to get on the plane, the tenseless theory alone cannot account for a crucial fact that the tensed theory can; namely, it is now 4 pm.
3. It allows for evil to be truly vanquished.
When Christ comes and the eschaton is fully realized, evil events and actions will not exist. On the B-theory, the worst evils ever committed are always there, in their full existence, indexed along the block. Nothing God does or even can do rids these actions from the block. This seems like an issue, but it may not move everyone.
4. It gives a more intuitive understanding of temporal persons.
The issue of how to persist through time is one that has plagued philosophers. An “essential parts” doctrine might make sense here, where you persist through time just in case you have the parts that are essentially you present at any and all times at which you exist (substance dualism tends to do well with this). However, at the B-theory, it is difficult to see how it is that you exist at any one time. You are a discrete bundle of time-slices that is not wholly present at any one time. Are any of the individual time-slices you? It seems that it may not be. Regardless of any putative answers, on an A-theory you are wholly present at every moment at which you exist; this is far more intuitive than the B-theory.
Nonetheless, B-theorists believe they can offer advantages over the A-theory as well, and they are worth explanation:
1. God may be able to avoid being temporal.
On an A-theory, it seems difficult to construe God as being outside of time; if there is an objective now, it seems that if God is sustaining this present “now” in existence, then God is sustaining the present “now” in existence, well, now. If that is so, then on an A-theory, God is in time. While there are potential answers that some A-theorists may attempt, it’s worth noting that, on B-theory, it looks like God can simply interact with the spacetime block and, since time just is the block, be outside of it.
2. The redeemed are experiencing their glorification.
While it would be a mistake to say the redeemed are experiencing their final glorification now (at least, it would be if they are not currently dead nor are we in the eschaton), it nonetheless is true, on a B-theory, that the redeemed are worshipping around the throne in eternal bliss with God at particular spatiotemporal points that lie along the block in our relative (but non-literal) future. The A-theory cannot account for this, instead having to say that, while the Earthly living saints are not experiencing eternal bliss in glorification with God, one day they will—that will become reality. This point in favor of the B-theory has been theologically attractive to many.
Interestingly, which theory you adopt (or unconsciously assume) can lead you to accept or reject various other arguments in philosophical theology. Even now, I find myself reading an essay and will think, “This only works if such-and-such theory of time is true!” So what do I think? I think the A-theory is true, as I find myself very attracted to intuitive views in philosophy. My point in this article, though, is to suggest that any view one adopts will have problems, and any view one adopts will have advantages over the other. Pick your favorite set and have fun! J
 I am aware that there are more than two theories; there are different versions of A and B theories, and there are even hybrid attempts between the two. Nonetheless, I am going to try to describe either what the various views have in common (e.g., what makes a theory an A-theory), or the most popular version of one of the major two theories. I hope I can be forgiven for this in a blog post.
 I’ve noticed something quite interesting about the popular understanding of time, however: people hold contradictory notions of it. I suspect that large part of this is due to people’s natural intuitions clashing with common scientific language about the nature of time. That’s a post for another . . . time, I guess.
 Mitch Stokes, How to Be an Atheist (Wheaton, IL: Crossway, 2016), 107. It is worth noting that after he had developed his theories on relativity and espoused them, he came to accept a realist view of these entities.
 It should be noted, however, that there is a crucial caveat which must be addressed: for those who do not embrace some kind of annihilationism or universalism (which I do not), then it may be that evil events take place throughout eternity, on either view. This would be so if the condemned in Hell accrue further punishment by acting in evil rebellion toward God.