Can Writing Enact Social Change?

I think that writing can promote social change, but how strong the effects are may vary due to several factors. If you write a motivational piece, encouraging people to lose weight, and post it at a gym where people who are already in the process of losing weight, it won't make a difference. But if you were to post it where many overweight people are able to view it, you can make a bigger impact. in other words, when you write and wish to cause social changes, you have to know the right location, and communicate to the right people to do so.
Writing is a way for people to communicate or just get a message across to people who will feel/show sympathy, or can relate to. When, and how these people get to read a piece of literature they can relate to, then there will be social change.
It also depends on what kind of social change you want to happen. If the changes are more subtle, than the chances are that more people will join the cause, but if it is something more outrageous, and out of the ordinary, the less chance there is that people will follow. For example, more people will be willing to sign a petition, than join a rebellion that requires violence and whatnot.
To wrap up, i do believe that writing can enact social change, but the chances may vary on the who, what where, and how of the subject.