Reblog if you believe in copyrights. Help this spread all throughout tumblr in order for the newbies to get the picture.
Reblogging without credit doesn’t necessarily violate anyone’s copyright, although doing so does make you a dick. Note also that there are some cases where reblogging may infringe. For example, if you post an entire song or book, that is not fair use—even if you give credit.
Copyright law is amazingly simple, but big media & publishers are seeking to complicate it by eliminating fair use and locking up orphan works for eternity.
EDUCATE YOURSELF and keep creating interesting and original content!
Oh, and don’t be a dick … reblog with credit!