"Theories predict, but do not explain? What good is that?"

There's a reason we ask new people to learn a little bit about the LW community before posting. Anticipation of experience as the measure of your belief is a fundamental concept here.

You can think of it this way: a good explanation lets us make many new predictions. And that is the sole use of explanation. (Does that sound too strong?)

EDIT: Really good explanations can be formulated mathematically, and from mathematical 'laws' you can derive predictions, as Desrtopa implies about Newton's laws.