I just saw your message in 2014!
Yes, in metaphysics we can defend the principle that every effect requires a cause. But it is wrong to say that every thing must have a cause. Some thing may not need a cause, namely, the First Cause Uncaused, which is God.
An effect is a being which does not fully explain its own existence, and hence, needs a reason outside of itself to explain what it fails to explain of itself. We call that external explanation a cause.
Hard to grasp, but cause and effect must be simultaneous – NOT going back in time. As St. Thomas says, if you remove the cause you remove its effect. Thus, effect does not follow cause temporally (contra Hume).
Again, following St. Thomas, the universe COULD be eternal. That the world began in time is an article of faith, not reason. That the cosmos be uncaused is impossible, not because it is eternal, but because it is finite, and finite beings need a cause. [email protected].