The "subject matter" for copyright is defined in 17 U.S.C. section 102. Part (a) of the statute defines what can be copyrighted (essentially, original works of authorship) and part (b) defines what cannot. For policy reasons, the (b) part says, in effect, that even if something is an original work of authorship (meaning it is expressive and creative and otherwise eligible for copyright), nonetheless certain things cannot be copyrighted because this would not further the goal of copyright law (to further the progress of science and the arts) and would otherwise potentially harm society.

Section 102(b) reads as follows: "In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work."

The idea here is not to give anyone a monopoly via copyright over such fundamental concepts as ideas, etc. Things that are purely functional within systems and the like fall within 102(b) and cannot be copyrighted even if they are otherwise expressive. That is what Google is arguing about the 37 Java API packages in this case.

> they require creativity and insight to create.

So did Huffman encoding. So did the Laplace transform. So did quicksort, red-black trees, and hell, even the Universal Turing Machine. These are all the result of many hours of creative endeavor, yet they are none of them copyrightable.

This is the same thing that makes Wolfram's claims of ownership of the existence of a proof of Rule 110 CAs as universal calculators particularly onerous.

I gladly accept grellas's arguments. But your examples are ideas, which would fall under patents, not copyright. Source code does fall under copyright, so we need reasoning to explain why APIs - which are a part of source code - do not.