There was a series of articles in Skeptics magazine earlier this year, that presented both sides of the porn argument (is it harmful or not?)

1st article. How Porn Is Messing with Your Manhood

by Philip Zimbardo, Gary Wilson & Nikita Coulombe

2nd article (a response to the first) Skeptical of the Porn Skeptics

by Marty Klein, Ph.D

3rd article: More on Porn: Guard Your Manhood—A Response to Marty Klein

by Philip Zimbardo, Gary Wilson & Nikita Coulombe