Just as some misguided people react with hostility to the fact that the copyright monopoly is not a birthright, they can react with hostility and demand a response to how sharing is “justified”. This, too, is misguided.
One example could be seen in the Reddit thread about The Pirate Bay being the world’s most efficient public library. For a while, the top comment was “whatever helps you justify it” (as in, “invent whatever excuse you like to try justifying the sharing of culture”). This is a misguided expression based on the false premise that sharing knowledge and culture needs to be justified.
It is completely the other way around.
Humankind and civilization have advanced due to and because of people sharing knowledge and culture, and humankind has never advanced when culture and knowledge have been locked up and contained. Sharing knowledge, information, and culture is also a good deed on an individual-to-individual basis. Whenever the ability to share and partake in knowledge and culture has been prevented, such as the burning of the library at Alexandria, it has always been regarded as a disaster for humanity in the history books.
And yet, some people believe that sharing – whether over The Pirate Bay, direct handover, or whatever other mechanism – needs to be justified.
It is true that the copyright monopoly has come at odds with the natural behavior of sharing and the right to share. But to enforce this monopoly, much more vital ideas in society – such as the postal secret – must be sacrificed, not to mention our cultural heritage. That is neither just nor reasonable, so that is what needs justification. It’s not just the copyright monopoly law itself that needs to be justified, but also individual compliance with the unjust monopoly law, on a case-by-case basis.
When somebody angrily asks you how you can share this and that knowledge “without permission”, state it as it is, that they are misguided, and ask how they could possibly justify requiring permission to share knowledge and culture. That goes counter to all of humanity’s history. Also, make sure to make a point that sharing never requires any kind of justification. (The current copyright monopoly laws are not enough of a justification, obviously, as they are unjust and completely out of touch with people’s actual and natural behavior.)
Sharing knowledge and culture is the natural state.
Therefore, any restrictions on sharing require very careful and strict justification.