Yes it is Possible you have to modify the Member Access Mask, and set it to read only
I've changed the access masks so that "NO ACCESS" and "READ ONLY ACCESS" has 'read' set to TRUE.
But when I try to access the URL of an existing forum it just prompts me to login instead of allowing me to 'read' / view the material there.
if it matters, im using version 1.9.3.
again, what Im after is a solution where a general / anonymous user is allowed to see all the content / material / forums and underlying posts. whether it is through javascript to 'login' the user automatically (on page load) or through something in the forum admin (rules for user access to content).