People thought about things differently in times long gone, and it can be very hard to pin down exactly what the differences are. They usually go unmentioned, and so unnoticed, in the background.

Take something so simple as cause and effect. Classical or even medieval thought went one way. Following them, we would say that when kid A pushes kid B into the swimming pool with a running shove, it was the very movement of Albert that caused, at the moment of contact, the untimely dunking of the unsuspecting Bradley. The motion of one body causes the motion of another.

But if we were to follow a more modern thinker, such as David Hume (1711–1776), we might think that things don’t really play that way. According to him, when we say that one thing caused another, we mean that it happened first (priority), that the two were close together (proximity), and that there is a necessary connection between the two. He gave the easy example of billiard balls. First, the cue ball is moving toward the 8-ball. Now, the 8-ball is moving away from the cue ball. Did the cue ball cause the motion of the 8-ball? Something changed between the first and the second moment. Certainly the two balls were very close together when the change happened, and the cue ball was moving first (proximity and priority). But was there really a necessary connection between the two? Sure, every time you’ve hit two pool balls together, they’ve transferred motion, but who’s to say it would happen every time?

Hume’s solution was that “cause” and “effect” aren’t real things in the world. There are real events, and because they are so often juxtaposed in space and time, we presume a necessary connection between them just because we’re inclined to think that way. So when the lifeguard calls to Albert, “Hey, what’s going on?!” and Albert says, “I don’t know,” he might just be right.

Now, this may seem quite silly to you. You are probably perfectly willing to say that the motion of one ball causes the motion of the other and that Albert causes the motion of Bradley. You are probably just as happy to say that the same thing would happen any time Albert gave Bradley a poolside push, and even that the same thing would happen with any two kids, provided that Bradley isn’t velcroed to the ground. It’s all silly. And silly ideas can’t be dangerous, right?

But here’s the rub. For most normal events, we think in the old way—we punish the man holding the smoking gun. But while Hume’s ways of thinking aren’t usually mentioned outside a classroom, they remain in the background of our modern-day thought. Such ideas have given us a suspicion that we just “understand” things as we would like them to be rather than knowing the way they really are.

This wears away our sense of a reality that is the creation of the True God. It erodes our trust that He made us to know the truth, that He made us to know Him. Finally, it corrodes our trust in Our Father Himself. And, as the Broadway musical said, that spells Trouble—with a capital T, and that rhymes with P, and that stands for pool.

Image: Currier and Ives, Billiards. A Double Carom