First a bit of a logic lesson. Formal logic is a bit structured and tedious, but quite beneficial to learn. We are told that:
1. S is an M.
2. All M’s are P.
3. Therefore, S is P.
This form is called a syllogism, and the example here meets the formal structure required by logic. The important thing to note here is that if 1 and 2 are true, then S is P is 100% absolutely certain, without any doubt or opinion. The problem is that S, M, and P are abstractions, and we cannot tell if there are such things in the real world. So let’s move to the next example, and make it a bit more real:
1a. Abe Lincoln is a man.
2a. All men are mortals.
3a. Therefore, Abe Lincoln is mortal.
We now have something that we try to relate to the real world. Practical people like you and I are called common sense realists, and we can be absolutely certain that the logic here is solid, and Abe is a man, and he is mortal.
Philosophers, however, are generally not common sense realists. They would have a couple of objections. First, are we absolutely certain Abe is a man? It could be he was a woman and fooled everyone. It also could be that all the history books are mistaken. Second, 2a presents us with the problem of induction, which simply says that we cannot know that all men are mortals unless we somehow test every single man to see if they are all mortal, a task that is quite impossible. So the philosopher would say that while the logic is solid, we cannot be absolutely certain due to these objections.
We will call these ridiculous philosophical objections (RPO), for practical people like you and I do not put any weight to such nonsense as all the history books being wrong, or that somehow Abe was the one person ever found who was not mortal. At the very least such RPO are not reasonable, and if we were to use them, we would be guilty of not being reasonable. But since you and I are practical, reasonable people, we will not fall for such nonsense.
Now we move to the area we care more about, namely the kalam cosmological argument. The current champion of kalam is Dr. William Lane Craig, but there are others. It says:
1c. Everything that has a beginning has a cause.
2c. The universe had a beginning.
3c. Therefore the universe had a cause.
Now you and I both know that any objections to 1c fall under the heading of RPO, for everything we’ve ever experienced that has a beginning was caused. We are too practical to base our eternal destiny on such nonsense as philosophical objections that we both know do not apply to reality. That leaves us with 2c. The evidence keeps pointing to the conclusion that 2c is true. Since we have limited time, I will merely point out that the experts in cosmology claim to accurately tell the age of the universe. If it has an age, then it had a beginning. The universe either had a beginning, or it is eternal, without beginning. The age of the universe, plus all of the other signs that support the idea of a beginning, make it harder and harder to deny 2c.
Practical, reasonable people will therefore conclude that the kalam argument is certain proof that the universe was caused. Since appealing to RPO moves us to the realm of unreasonable conclusions, we know better than to go there. For those philosophers in the crowd, or even scientists who think they have an objection, I would point you to Dr. Craig’s several dozen journal articles over the last couple of decades, where he deals with the strongest objections that could be levied by the proponents of RPO and scientific speculations. If we have doubts, we will do our homework properly, and will not fall guilty to basing our eternal destiny on what we find on YouTube.
Practical, reasonable people will then conclude that the kalam argument is a certain demonstration for the existence of a creator who is outside the universe.