The deepest question of philosophy is why do contingent beings exist at all? By a contingent being, a Nina being, which exists, but which might not have existed. Examples? Mountains? Planets? Galaxies? You and me? Such things might not have existed. By contrast, a necessary being is a being which exists by a necessity of its own nature. Its non-existence is impossible. Examples? Many mathematicians believe that numbers and other abstract objects exist in this way. If such entities exist, they just exist necessarily. Now, experience teaches that everything that exists has an explanation of its existence, either in its own nature if it exists necessarily or in an external cause if it exists contingently. So, what about the universe? By the universe, I mean all of space-time reality, not just our observable portion of it. What is the explanation of its existence? Well, since the universe is contingent in its existence, the explanation of the universe must be found in an external cause, which exists beyond time and space by a necessity of its own nature. Now, what could that be? There are only two kinds of things that could fit that description. Either abstract objects, like numbers, or God. But abstract objects don't stand in causal relations. The number seven, for example, has no effect upon anything. And therefore, it follows that the most plausible explanation of the universe is God. Hence, the existence of contingent beings makes God's existence more probable than it would have been without them. Although it presented this reasoning inductively, we can also put it in the form of a deductive argument, Premise 1. Everything that exists has an explanation of its existence, either in its own nature or in an external cause. 2. The universe exists. 3. If the universe has an explanation of its existence, that explanation is God, from which it follows logically, 4. Therefore, the explanation of the universe is God. That's the explanation for the existence of contingent beings is to be found in God. 2. The origin of the universe. My first argument is consistent with the assumption that the universe is beginningless or eternal in the past. But is it? There are good reasons, both philosophically and scientifically, to doubt that the universe is beginningless. Philosophically, the idea of an eternal past seems absurd. Just think about it.