This is the third installment in our series on the Kalam. You can view part two, here, and part one, here. In this blog post, we now jump to the philosophical reasons for why we think the universe had a beginning. There are two philosophical reasons that give us reasonable certainty that the universe began to exist. These are:
An actual infinite number of things cannot exist.
and…
You can’t pass through an infinite number of events one at a time.
In regards to the first philosophical reason, some may ask, “How is this even an argument for the beginning of the universe?” In order to demonstrate how an infinite number of things cannot exist, I want to use an example called Hilbert’s Hotel. This is the brainchild of the great German mathematician David Hilbert. Hilbert first invites us to imagine an ordinary hotel with a finite number of rooms. Suppose, furthermore, that all the rooms are full. If a new guest shows up at the desk asking for a room, the manager says, “Sorry, all the rooms are full,” and that’s the end of the story.
But now, says Hilbert, let’s imagine a hotel with an infinite number of rooms, and let’s suppose once again that all the rooms are full. This fact must be clearly appreciated. There isn’t a single vacancy throughout the entire infinite hotel; every room already has somebody in it. Now suppose a new guest shows up at the front desk, asking for a room. “No problem,” says the manager. He moves the person who was staying in room #1 into room #2, the person who was staying in room #2 into room #3, the person who was staying in room #3 into room #4, and so on to infinity. As a result of these room changes, room #1 now becomes vacant, and the new guest gratefully checks in. But before he arrived, all the rooms were already full!
It gets worse! Let’s now suppose, Hilbert says, that an infinity of new guests shows up at the front desk, asking for rooms. “No problem, no problem!” say the manager. He moves the person who was staying in room #1 into room #2, the person who was staying in room #2 into room #4, the person who was staying in room #3 into room #6, each time moving the person into the room number twice his own. Since any number multiplied by two is an even number, all the guests wind up in even-numbered rooms. As a result, all the odd-numbered rooms become vacant, and the infinity of new guests is easily accommodated infinitely more guests. And yet, before they arrived, all the rooms were already full! If Hilbert’s Hotel actually existed, it would have a sign posted outside saying: “No Vacancy (Guests Welcome).”[1]
Now we jump to the second philosophical reason to believe that the universe began to exist. The series of past events has been formed by adding one event after another. The series of past events is like a sequence of dominoes falling one after another until the last domino, today, is reached. But no series that is formed by adding one member after another can be actually infinite. For you cannot pass through an infinite number of elements one at a time. This is easy to see in the case of trying to count to infinity. No matter how high you count, there’s always an infinity of numbers left to count. But if you can’t count to infinity, how could you count down from infinity? This would be like trying to count down all the negative numbers, ending at zero: …-3,-2,-1, 0. This seems crazy. For before you could count 0, you’d have to count -1, and before you could count -1, you’d have to count -2, and so on, back to infinity. Before any number could be counted an infinity of numbers will have to have been counted first. You just get driven back and back into the past, so that no number could ever be counted. But then the final domino could never fall if an infinite number of dominoes had to fall first. So today could never be reached. But obviously here we are! This shows that the series of past events must be finite and have a beginning.[1]
Based on these two philosophical arguments, it seems reasonable to conclude the universe had a beginning.
[1] I discovered these examples in William Lane Craig’s book, On Guard: Defending Your Faith with Reason and Precision (David C. Cook, 2010).
