You can not claim to have a free open society if people fear speaking their thoughts. It may be tempting to shout someone down if you feel they are spreading harmful words but others may consider your words to be harmful. Viewing it as acceptable to be able to make others fear speaking their beliefs makes for a society where the loudest and most intimidating have the most influence, who are not necessarily the most knowledgeable or wisest.
[What I belive to be important] [Thyme]