The Great Debate

Is God the only possible explanation for our existence?

The Kalam Argument

Father Ronald Tacelli

The Arabic word kalam means literally 'speech', but came to denote a certain type of philosophical theology — a type containing demonstrations that the world could not be infinitely old and must therefore have been created by God. This sort of demonstration has had a long and wide appeal among both Christians and Muslims. Its form is simple and straightforward.

  1. Whatever begins to exist has a cause for its coming into being.
  2. The universe began to exist.
  3. Therefore, the universe has a cause for its coming into being.

Grant the first premise. (Most people — outside of asylums and graduate schools — would consider it not only true, but certainly and obviously true.)

Is the second premise true? Did the universe — the collection of all things bounded by space and time — begin to exist? This premise has recently received powerful support from natural science — from so-called “Big Bang Cosmology.” But there are philosophical arguments in its favor as well.

Consider: Can an infinite task ever be done or completed? If in order to reach a certain end, infinitely many steps had to precede it, could the end ever be reached? Of course not — not even in an infinite time. For an infinite time would be unending, just as the steps would be. In other words, no end would ever be reached. The task would — could — never be completed.

But what about the step just before the end? Could that point ever be reached? Well, if the task is really infinite, then no fewer steps could have preceded that point than the final one. In other words, an infinity of steps must also have preceded it. And therefore the step just before the end could also never be reached. But then neither could the step just before that one. In fact, no step in the sequence could be reached, because an infinity of steps must always have preceded any step: must always have been gone through one by one before it. The problem comes from supposing that an infinite sequence could ever reach, by temporal succession, any point at all.

Now consider this: If the universe never began, then it always was. If it always was, then it is infinitely old. If it is infinitely old, then an infinite amount of time would have to have elapsed before (say) today. And so an infinite number of days must have been gone through, or completed — one day succeeding another, one bit of time being added to what went before — in order for the present day to arrive. But this exactly parallels the problem of an infinite task. If the present day has been reached, then the actually infinite sequence of history has reached this present point: in fact, has been completed up to this point — for at any present point the whole past must already have happened. But an infinite sequence of steps could never have reached this present point — or any point before it. So: either the present day has not been reached, or the process of reaching it was not infinite. But obviously the present day has been reached. So the process of reaching it was not infinite. In other words: the universe began to exist.

Therefore: The universe has a cause for its coming into being, a Creator.

QUESTION 1: We believe we're going to live forever with God. So we believe the future will be endless. How come the past cannot also be endless?

The question really answers itself. We believe that our life with God will never end. That means it will never form an actually completed infinite series. In more technical language: an endless future is potentially — but never actually-infinite. This means that although the future will never cease to expand and increase, still its actual extent will always be finite. But that can only be true if we and all created reality had a beginning.

QUESTION 2: How do we know that the cause of the universe still exists? Maybe it started the universe going and then ceased to be.

Remember: we were seeking for a cause of spatiotemporal being. This cause created the entire universe of space and time. And space and time themselves must be part of that creation. So the cause cannot be another spatio-temporal being. (If it were, all the problems about infinite duration would arise once again.) It must somehow stand outside the limitations and constraints of space and time. It is hard to understand how such a being could “cease” to be. We know how a being within the universe ceases to be: it comes in time to be fatally affected by some agency external to it. But this picture is proper to us, and to all beings limited in some way by space and time. A being not limited in these ways cannot “come” to be or “cease” to be. If it exists at all, it must eternally exist.

QUESTION 3: But is this cause God — a He and not a mere It?

Suppose the cause of the universe has eternally existed. Suppose further that this cause is not personal: that it has given rise to the universe, not through any choice, but simply through its being. In that case it is hard to see how the universe could be anything but infinitely old, since all the conditions needed for the being of the universe would exist from all eternity. But the Kalam argument has shown that the universe cannot be infinitely old. So the hypothesis of an eternal impersonal cause seems to lead to an inconsistency. Is there a way out? Yes — if the universe is the result of a free personal choice. Then at least we have some way of seeing how an eternal cause could give rise to a temporally limited effect.

We grant of course that the Kalam argument does not prove everything we believe about God. But what proof does? Less than everything, however, is far from nothing. And the Kalam argument proves something central to our belief in God: that the universe is not eternal and without beginning; that there is a Maker of Heaven and Earth. And in doing so, it disproves the picture of the universe most atheists wish to maintain: self-sustaining matter, endlessly changing in endless time.

read Raven’s response