Wednesday, July 11, 2007

Some arguments for the finitude of the past

The first of William Lane Craig's arguments for the existence of God is the Kalam Cosmological Argument. It goes:

1. Whatever begins to exist, must have a cause of its existence.
2. The universe began to exist.
3. Therefore, the universe has a cause of its existence.

The first premise of the argument seems intuitive, at least at first. Suppose you and I are eating lunch. You turn your head away from the table, only to discover that a bunny rabbit is munching on your salad. You ask "how did that rabbit get there?" and I say "Funny thing. It just popped into existence. No cause or anything, it just happened." You wouldn't take me seriously, right? Well, what goes for bunny rabbits should go for universes. To say that the universe began without a cause doesn't make sense.

Or does it? Opponents have argued that in Big Bang theory the time begins when the universe begins. So there never was a time before the Big Bang in which time existed but the universe did not.

Somehow, this doesn't in my mind alleviate the need for a cause. It seems to me that something that doesn't exist contingently should have existed through an infinite duration. if it doesn't have a cause, similarly, it should exist through an infinite time, or be outside of time.

But why believe that the universe had a temporal beginning? The most prominent theory in cosmology seems to still be the Big Bang theory, a theory that says that there was a beginning. But Craig also endorses arguments that there can't be an infinite number of past moments.

Think about this. Suppose I ask you to loan me some money. I offer you 100% interest compounded daily. But you, quite rationally, want to know the term of the loan. I reply that even though it may take an infinite length of time to pay it back, you'll get your money. This somehow doesn't satisfy you. But if the past is infinite, that means that there are an infinite number of moments in time that have ALREADY HAPPENED. How is that possible?

I have a link to a presentation of three arguments in favor of the claim that the past must be finite and not infinite.

15 comments:

Don Jr. said...

Victor,

A countermove--one that I once found unanswerable--which I have encountered, derives from what you say in your 4th paragraph. You note that if time began with the Big Bang then there never was a time before the Big Bang. (One should still note that this doesn't defeat the kalam argument since it still means that the universe had a beginning.) The countermove came when someone drew the following, what I now think to be incorrect, inference: if there never was a time before the universe began, and thus the universe has existed for all time, then the universe has always existed. But inferences must be meaningful. If always simply means "for all time" then we don't have an inference but a mere tautology--and one with which I would agree. However, if always is to suggest that the universe, in a sort of theological language, is eternal, then I don't agree with the inference.** (Note: any use of "always" hereafter will be in the latter sense, not the tautological sense.)

I have existed for all my life. For me to claim that therefore I have always existed is to presuppose that existence isn't possible outside of my life. This can be transferred over. To suggest that because the universe has existed for all time it, then, has always existed is to presuppose that existence isn't possible outside of time.

**Unless I'm missing something, this interpretation doesn't seem to truly be open, since eternal either means "for all time," in which case we'd be back to the tautology, or timeless, and the universe is clearly not timeless.

(As an aside, this is only an issue for those who believe that creation, or the beginning of the universe, corresponds with the beginning of time. There are many who don't hold to this belief though.)

Anonymous said...

Is it possible to engage in thought outside of time?
Could one engage in action outside of time?

Is time possible without space?

es said...

I have read somewhere (Sagan?) that it is a mistake to think that there should be nothing instead of something. The thinking is that it is at least as likely that something has always existed as that nothing once existed.

in·e·luc·ta·ble said...

Wow! Thanks for your insightful entry Victor. When I first acquired an interest on our existence, astronomy and science in general, I began to debate about similar issues. I always strongly believed that there HAS to be a God because the Universe can't just pop into existence.(like your rabbit analogy)
Although quantum theory implies that particles can pop in-and-out out existence, there, according to my logic, had to be some sort of beginning.

A close friend was my unofficial collaborator when we discussed issues like these and no matter how hard I tried to convince him of my viewpoint he always disagreed with me. He believes that our Universe is endlessly and perpetually BigBanging and BigCrunching and that time has existed and will exist forever.

According to Einstein's General Theory of Relativity, Time and space are entwined and therefore, time cant exist without space and vica versa. With that in mind; what is the Universe expanding into? And won't time stand still if the Universe didn't expand nor contract? I.O.W; For us to experience time like we do, isn't this because of the Universe expanding?

Anonymous said...

"But if the past is infinite, that means that there are an infinite number of moments in time that have ALREADY HAPPENED. How is that possible?
"

How is it possible that God had ALREADY been around for infinity before the universe was created?

Victor Reppert said...

Anonymous: The KCA requires an atemporalist view of God, otherwise God falls into the same problem that the universe falls into. Craig makes that explicit.

Anonymous said...

"The KCA requires an atemporalist view of God, otherwise God falls into the same problem that the universe falls into. Craig makes that explicit."

What does it mean for God to be an atemporal being? Is it meaningful to say that an atemporal being has always existed? What do words like "always" or "forever" mean without time?
How is an atemporal being able to think or do things like create the universe?
Sorry, but this KCA thingey seems to create more problems than it solves.:-)

exapologist said...

For a careful and thorough reply to the Kalam cosmological argument, see Wes Morriston's articles at his department webpage (which can be found at the website for the Philosophy Department at the University of Colorado, Boulder).

SteveK said...

There are a number of ways to show that an infinite past is impossible. For the intuitive people, the example that Victor gave is good. Another simple way is just to say "If you can't get from here to infinity (distance), what makes you think you can get from infinity to here?"

Calculus is the best, most objective, way to show that an infinite past is impossible. Check out infinite series.

Clayton said...

I suppose my worry is just that the intuitive causal principle is not 1. but:
1* Whatever begins to exist must have a case of its existence that exists prior to it.

It surely is more intuitive than:
1** Whatever begins to exist must have a cause but its cause needn't exist prior to it.

However, 1* won't help the argument given Big Bang Cosmology. Instead, 1** is needed, but the idea of a cause of x that does not temporally precede x is harder to make sense of than an uncaused x (at least, to my mind).

Øystein said...

I think this post by Lazarus is quite helpful:

http://www.iidb.org/vbb/showpost.php?p=2207617&postcount=23

Anonymous said...

For es:
Bede Rundle's "Why There is Something Rather Than Nothing," is maybe what you're looking for.

Anonymous said...

'1. Whatever begins to exist, must have a cause of its existence.'

What causes free will decisions to begin to exist?

I know, contra-causal libertarianism does not mean that fee woll decisions have no cause....

Sturgeon's Lawyer said...

There are two responses to this, one from the scientific point of view, and one from the religious. I believe they are compatible.

From the scientific point of view:

Causality is a property of time. For cause to precede effect, there must be a "before."

Time is a property of the universe, or, rather, a dimension of it -- "spacetime." Because the universe comes into existence at the singularity called "the Big Bang," so too does time.

Thus, there is no time "before" the Big Bang; and thus, there is no causality before it.

From the religious point of view:

God does not exist in-Time. God, in-Eternity, created Time. The nature of Eternity is unchanging, without Time or chronological sequence.

To speak of God being "before" the Universe is then an error of human language; God is prior to the Universe not chronologically but logically. To God, though He creates the Universe, it (in all its moments from creation to End) is always-already present to Him.

Steve Lovell said...

I've been holding off making any comment on the KCA, waiting for someone to actually present some thoughts of there own rather than simply link to external sources.

A little of that has happened, but not alot. Still, I decided it was time ...

Craig uses two philosophical arguments for the finitude of the past. One has to do with the impossibility of actual infinites. The other has to do with "traversing infinites".

Actual Infinites
Although Craig is well aware of Cantor's mathematical theories of the infinite and that such things are logically consistent, he continues to insist that his argument shows that such infinities are metaphysically impossible while granting that Cantor has shown them to be logically possible. I am simply unable to see how this argument is supposed to work once we grant the logical possibility of actual infinites. How does one demonstrate the weaker form of impossibility without also demonstrating the stronger? Why won't the solutions to the logical problems also suffice at the metaphysical level? I've read lots of Craig, and I've never seen this question addressed.

Traversing the Infinite
This has always seemed the more promising line to me, but I'm still not convinced. According to this line of argument, time having reached the present point by "coming through" all of an infinite past is like thinking we'll time will ever get through "all of" an infinite future. If we can never count up from zero to infinity, we should it be any more possible to count down from infinity?
This argument depends on subtle confusions. It is, of course, impossible when counting at a constant rate to begin at zero and get through all the numbers. Still, there is no number which will not be reached given enough time. All we seem to mean, then, is that we will not reach the end ... but that's because there is no end to these numbers. So, when we say we cannot count from zero to infinity what we really mean is ...

(A) Necessarily, at no point in the future will we have no further numbers to count.

The argument depends on the thought that the same logic applies to counting down from infinity to zero. Now in one sense the same logic does apply, and in another it does not. The important difference, between the past and the future is that in the case of the future the "infinite end" of the counting series is later than the finite end, while in the case of the past, the infinite end of the counting series occurs earlier. As a result the equivalent to (A) is not (B) but (C).

(A) Necessarily, at no point in the future will we have no further numbers to count.

(B) Necessarily, at no point will we have had no further numbers to count.

(C) Necessarily, at no point in the past will we have had counted no numbers.

Or, to put the point differently. While it is true that

(A') If the future is infinite, we will never live through all the future and get to the end.

The parallel for the past is not

(B') If the past were infinite, we could never have lived through it all and got to the present.

but rather

(C') If the past were infinite, we could never have lived through it all having started from the beginning.

This is why Mackie and others famously accuse Craig of assuming that the past has a beginning (or even an infinitely distant beginning).

But (C) and (C') pose no problems for the defender of an infinite past. They think we have "always been counting", that there was no beginning.

One other version of the "transversing the infinite" argument can go like this: suppose you walk into a room and hear someone saying "... three, two, one, zero. Thank goodness. I've finished counting down from infinity". If on asking when he started counting down, you were told that he'd always been counting, you might begin to wonder how come he only finished the countdown today, if the past is infinite, the amount of time he'd had for his countdown was just as infinite yesterday as it was today ... so why didn't he finish yesterday? Well, imagine that our man only counts down through 10 numbers a day. One reason he might cite for only finishing today is that yesterday he began counting down from 20 and only counting ten numbers a day naturally couldn't reach zero (or one) until today. You might then be tempted to ask how come he only reached 20 yesterday ... but it is obvious that an exactly parallel answer will be given. We are forced to ask rather "On any day, where you counted from N+10 to N+1, why weren't you rather counting from N to N-9?" To this more general question our man is not likely to be able to give an answer.

Now, does this suggest a possible argument against the infinity of the past? Might we argue that it would not allow us to explain why today didn't come about earlier? I don't think so. The events of today didn't come about earlier because the events of today are preceded by 24 hours by the events of yesterday, and those didn't come about until yesterday. If we push for the more general question, we end up, in effect, why the whole history of the universe didn't happen one day earlier. But, as my PhD supervisor pointed out, this question is no more evidently meaningful than asking "Why isn't the whole universe three feet to the left?"

Steve