I would contend that there can be harms involved even with porn that you might consider harmless; harms such as addiction, damaged relationships, objectification of partners. Porn can damage minds.
Many things (like alcohol) can be addictive and damage relationships. Who objectifies others should be a personal choice, censorship should not be performed for the purpose of protecting people from thinking in a certain way. Plenty of other information can damage minds too, can't it? Who's to decide which porn is more or less damaging, unless you support a blanket ban on all pornography? Come to think of it, even non-pornographic fiction can damage minds; films involving drug use, James Joyce's Ulysses.
> Who's to decide which porn is more or less damaging
Or just what is meant by 'damage'? Discourse here is unlikely to be a friendly academic discussion on the meaning of words, but instead another instance of the eternal question "Who? Whom?"
That is quite a monoatomically smooth polished and lubricated slope there. Truthful descriptions of somebody's past actions can damage relationships. Pointing out that your partner sleeps with someone else on every business trip can. Should telling you that your partner is cheating on you be a felony then? Should history books be banned because some get the completely wrong message and idolize Hitler and Stalin? And how does one define damage to the mind anyway?