In Our book, Nichols writes, "When persuasion regarding a particular issue is the goal, reason is a very valuable tool. Reason or logic carries a discussion from premises through well-reasoned arguments to a conclusion. However, often there is a no clear-cut solution to a real life problem, and logic alone cannot persuade.

What i think Nichols means by this is you need reason and logic when watching documentaries or films. If you want people to understand and like your documentaries you need to let them know the reason and logic behind it is. Also you do need both of these to make the film successful to the viewer. Even if there is no clear-cut solution to the problem having reason and logic will help the viewer understand it a lot more.