Causality is the theory of everything
1) Everything has a cause and an effect.
2) Everything is a cause and/or effect of some sort.
3) One cause can be the effect of another thing. One effect can be the cause of another thing.
There are two kinds of worlds:
1) a logical world, which follows the rules of Cause and Effect
2) an illogical world, which means there is no Cause and Effect.
So let's say there is a hypothetical world where there is a ball moving at the speed of light in a direction. If this was an illogical world, then that would mean there is no cause for the ball to do this. If there is no cause, and that the ball is moving, then why is it doing it? Why is there a ball anyways? Why is there even a world where there's a ball moving at speed of light? If there's no cause, then why's it doing it? That means, that in an illogical world, nothing would exist, because simply because there is no cause or reason for anything to exist.
Thus, an illogical world cannot exist. And if an illogical world cannot exist, then by process of elimination, there can only be a logical world. A world where there is cause and effect. Thus, that would mean that everything we know, everything that has happened, everything that we do, must have a cause and effect.