On page 151, the book mentions researching with an open mind, a rough topic is fine, but don't be so specific that it's difficult to find research in support. Narrow your research as more and more evidence comes available. Also, you may revisit your topic several times before deciding on the actual topic. This is something I 100% agree with.

I've encountered this issue in my other class when writing an annotated bibliography. I started with entirely too specific a topic and wasn't open minded to anything else. I wasted valuable time trying to research this topic before I broadened my topic only slightly, and evidence was easier and easier to find. The bibliography is much smoother now, and sources are abundant!!