Tom notes some attribution lost in space beginning with this, which came from this, which came from this. Amid this comical exchange on copyright, a questionable argument is taken for granted (in the comments on Jukes’ entry) by Doug Johnson who says:
When I asked [my son] if he didn’t feel it was wrong to deprive someone of his/her livelihood by denying them payment for their creative property [...]
This asking (“Don’t you feel it wrong to have deprived others by denying payment?”) depends upon the assumption that copying published information denies payment. Most certainly, file sharing does not necessarily include payment (hence “sharing”), but that’s very different than an active “denying” of payment. While the difference is subtle, it is significant and skews any copyright argument if not acknowledged.