[crxpandion]

The legal problem is that most software patents are plans for instructions for how to construct something tangible (albeit that is an abstract view). Which basically means that they lie in some grey area in between written works and designs for something.

I would argue that maybe a good rule is to force patents to applicable only on systems of certain size or complexity. That way algorithms and data structures would not be patentable but a method for mining large datasets would be. Similar to how a new dimension of a nut and bolt is not patent-able but putting a bunch of them together in a innovative way is.