Earlier quoted context omitted.
We have some evidence, because he wrote a manifesto.
Interestingly, Lessig explicitly dismisses the theory that Swartz was trying to "liberate" the JSTOR archive: http://www.theatlantic.com/national/archive/13/01/aarons-law...
Isn't it a little odd that Lessig doesn't mention the manifesto? It wasn't obscure, and was introduced by the prosecution as evidence.