A vs B Theory of Time in science?

Those familiar with William Lane Craig’s work know he is a presentist and defends the A-theory of time. I am curious what the scientific reasons are for A vs B theory of time. These are concepts I am not very familiar with, so I figured I’d give a brief account and see if you had any thoughts. It seems a majority of philosophers hold to a B-theory of time, and personally I see issues with each theory.

In essence, A theory of time says that time is tensed, and there is a real distinction between the past, present, and the future. B theory, on the other hand, refers to the tenseles theory of time, where past, present and future all exist simultaneously, and the passage of time is an illusion of our consciousness

A-Theory Pros:

  • Corresponds to our perception of the “flow” of time
  • Corresponds with “tensed” language
  • Corresponds with thermodynamics

A-Theory Cons:

  • Relativity seems to suggest time passes differently based on the frame of reference of an observer, which would seem to cast doubt on A-theory as a whole

B-Theory Pros:

  • Special relativity removes the past/present/future distinction
  • Change in tenseless terms is easier to describe logically under B-theory

B-Theory Cons:

  • Natural selection/evolution has serious problems under B-theory
  • Time-travel paradoxes (like killing your grandfather) seem more plausible under B-theory

Any thoughts? Which do you hold to?


B-theory, kinda. As far as we are concerned, we are limited to A-theory sequential time, but my contention is that God is omnitemporal, equally present in all of time.

Most recently mentioned just the other week, but also several other places:

(Where are you geographically? The video is only streamable in the U.S. and parts of Canada, but there is a full transcript. What is most pertinent is the bit about ‘spacetime slices’ starting at about 19:15.)

The real controversy in my opinion is whether space or time is infinitely divisible.

About 3 years ago I first learned about a block universe, and this is what I thought about it then:

Wow! So I decided to read a bit on block universe theory and found a helpful Wikipedia article on eternalism. Talk about a controversial subject among some very heavy hitters.

As I’m reading it, I can’t help but wonder how the philosophy of time would be explained by these people when solipsism is thoughtfully considered as a metaphysical possibility. A question of whether the beginning of the heavens and the earth is in the past or the present. Either way, this seems to obviously affect the interpretation of being and time.

An interesting quote for this topic:

“The fact that our best scientific theory of the origin and evolution of the universe supports a self-caused universe is much more likely on naturalism than on theism, and thus provides very strong evidence for naturalism over theism.”

The Great Debate 2008, infidels.org

Interesting, I’ll check it out. I agree that A vs B theory doesn’t really matter to God’s existence; in fact CS Lewis and Augustine saw God as outside of time, whereas Craig seems to think God existed outside of time but chose to enter into it.

Notice how this quote begs the question in favor of naturalism. Many of the people I talk to affiliated with these New Atheist-like websites tend to have a poor grasp on epistemology.

The distinction between eternalism, presentism, and a growing block time are very interesting. I wonder if there’s a watered-down explanation of the nuances of each for us layfolk.


Jesus humbled himself to the constraints of the linear sequential time that we experience, but I don’t think that applies to God our Father and the Holy Spirit, our Paraclete, so I disagree with Craig. We already know that time is malleable.

“A-Theory” There is a real distinction between past and future because of quantum physics. Superpositions collapse under decoherence and only one of the possibilities of the future is selected in a single actuality of the past and present.

Indeed! Philosophical theories which do not agree with human experience are of little value to human beings.

There is no suggestion about it – time does pass differently in different inertial frames. This is experimentally confirmed. But this has little to do with the distinction between A & B “theories.”


Relativity also makes a very clear distinction between past, present, and future. But it is not a universal distinction but a local distinction (i.e. specific to a particular point in space-time), and so the antiquated notions of absolute time and Euclidean space-time, have been discarded. It just means the universe is not like a motion picture composed of a sequence of frames or instances (that is not how space-time is structured in the physical universe).



I’m glad you made this point, because I read a book that I think overstated the case for B-theory by (perhaps implicitly) claiming it was a global distinction. I know very little about all this so it is helpful to me.

As for why natural selection has issues under B theory, the issue is all species would be equally old and ageless as the static spacetime block itself. As a result, no development of species can actually occur under B-theory. Evolution is usually defined as change over time, which implies A-theory via survival and reproduction (the order and progression of which is important). If B-theory is true, biologists need to come up with some other metaphysical mechanism for how species “progress.” This is difficult because it would seem causality itself would be out the window (or at least need to be seriously rethought). In other words, time does not seem to be a causal factor evolution under B theory.


B theory is why I dislike philosophy at times. It is very disconnected from reality. I say something stupid and THEN my wife gets mad at me. There is a sequence of before and after there. Cause and effect.

Calling time “an illusion of our consciousness” is a red flag for me. Everything might as well be an illusion. Time, free will, morality, truth etc. We are a meaningless cosmic accident. Let’s all go kill ourselves.


I’ll take A theory of time, for 300 dollars, Alex…er…Paul.
While God may be outside (as well as inside) of time, we are temporal creatures. I think God operates throughout time, and knows all that can be known, but does not intervene in the past to undo that which is done. He also allows us free will to chose our path, though he knows which path we will take. That seems paradoxical, and perhaps it is, but otherwise I agree that without variability in the future, existence would be a rather futile matter.

1 Like

A. Because I believe reality is subjective and determined by embodied experiences. When we abstract things so far away from our embodied experiences that constructs of reality take precedence over human experiences of reality, I think we lose the plot.

Embodied humans experience time in certain ways and have metaphors for understanding that embodied experience, most foundationally, that time is space. Others flow out of this conceptualization that time is a domain in which or along which we move toward destinations or that time itself moves in space; time is a path, time is a current, time is a line, time is a circle, time is a moving object

No matter what physics postulates or formalizes about time, humans will continue to experience it as embodied creatures and process those experiences with embodied cognition, and the result will be the reality that matters.


That is a good articulation of why I said “kinda” above. There is still the matter of how God orchestrates providence though, and it is not something we can get our heads around.

Not unlike randomness? :slightly_smiling_face:

To say that God exists outside of time already falls into the trap of the antiquated notion of absolute time. Time is not a singular thing. The correct way to say it is to say that God exists outside the space-time structure of the physical universe.

But neither do I believe that God exists within some alternate space-time structure or alternate time. God is not just a being who exists in an alternate universe. But this still doesn’t justify saying that God exists outside of time. Just because God’s existence is not bound within some external space-time structure doesn’t mean God exists outside of time.

Would you, for example, say that God exists outside of intelligence? To be sure God isn’t confined to intelligence any more than God is confined to some space-time structure. Surely God uses intelligence, right? Likewise God uses time… as… He… chooses.

Therefore it is foolish to think God cannot do the same sort of things what we can do which logically require a measure of time. But it does negate the sensibility of asking what God was doing for an infinite time before creation? Such a question falls into trap of the antiquated notion of absolute time which is something science has already discarded.

But that is theology of course… back to science…

I was expecting someone to ask… well then what is the universe like if it is not like a sequence of instances??? There is the standard answer of Minkowski space-time which draws this picture of a cone separating past and future.

But I doubt that does the job of replacing the idea of the universe as a sequence of instances (like a movie film).

Well… the film is a good approximation at a particular place in space-time like a tangent approximates a curve at a point of the curve. So what you do is carry out the usual sort of succession of approximation where you put together all the tangent lines at every point of a curve. In this case you put a movie film in every inertial frame at every point of space time and you refine the patchwork by adding more and more such films at more such points and inertial frames.

That would be like saying there is no changes as you move westward in the United States. And to say the mechanisms for change in evolution don’t work is like saying there cannot be any reasons for the changes as you move west in the United States.

In the B theory you just see time as being like a dimension of space. It is not an eradication of time but just doesn’t see how it is different from a spatial dimension. It is like a drawing of an evolution tree – all drawn out on the same piece of paper. And the reasoning for why those changes still work just fine. If the B-theory ignores anything it is not the changes in time but the many other possible ways that evolution could have played out – those don’t fit on such a evolution tree paper.

God’s omnitemporality has nothing to do with absolute time.

No, because like his omnitemporallity, his omniscience is an attribute, something he possesses.

Yes. The ellipses are unnecessary.

Yes, within the universe, because it is talking about space. God is not confined to space – he is omnipresent, in this cosmos… and in any other, if they exist.


I would still recommend watching the applicable part of the NOVA (unless you are a special relativity denier) if it is accessible to you and you haven’t seen it:

@Kendel would probably have something worthwhile to say about how this relates to Heidegger (perhaps “Being and Time”), and how important the human experience is to our understanding of the world. I agree in all these cases, that perhaps a 4D block universe/tenseless time makes sense for certain mathematical calculations, but I don’t think it’s fair to say that is how the world “is” given our experience with time. Consciousness is another thing that doesn’t seem easily reducible to the natural.

I’m curious what you mean by this. Do you mean truth is relative, or that our experience with reality is subjective?

1 Like


  • You may be amused to know that there are an infinite number of Light Cones in the Cosmos. At the vertex of each Light Cone is a hypothetical “observer” and there are an an infinite number of them in the universe, to be exact. :laughing:
  • Yes, they are exactly like the conceptually infinite number of virtual points in a line segment. They are not real things that can be counted, however.

Thank you for pulling me in here. I assumed this thread would be unapproachable for me. So, I haven’t even looked at this conversation.

I’m weeks behind on the reading I’ve wanted to do in the Forum. I’m hoping to catch up a bit soon. A lot of Real Life (RL) going on around here.

Re: MH — I have read a brief summary of an abstract of a quote of Heidegger, which contained 5 or 6 words translated from German, AND I can properly pronounce the title of Sein und Zeit.1 Other than that, Paul, I got nothing for you.
Unless you want to turn it into a reference question. I’d be happy to look for good resources.

1Alternately, I recommend the gorgeous album Time and Tide by the Split Enz; the title is a happy play on words.