Full Idea
There are four major problems about the laws of nature: a necessity problem (must they be true?), an idealisation problem (why is this preferable?), an ontological problem (their grounds), and a structural problem (their relationships).
Gist of Idea
We must explain the necessity, idealisation, ontology and structure of natural laws
Source
Brian Ellis (The Philosophy of Nature: new essentialism [2002], Ch.5)
Book Reference
Ellis,Brian: 'The Philosophy of Nature: new essentialism' [Acumen 2002], p.92
A Reaction
One might also ask why the laws (or their underlying essences) are the way they are, and not some other way, though the prospects of answering that don't look good. I don't think we should be satisfied with saying all of these questions are hopeless.