First, let me propose that pornography is voyeurism. I'll offer the TheFreeDictionary explanation of the predominate use and therefore current meaning of that term. I hope one does not disapprove I have not linked something along the lines of a Oxford dictionary explanation of the word. http://www.thefreedictionary.com/voyeurism
What is interesting here - perhaps overlapping with a philosophy of psychology inquiry - is that the typical person would feel abnormal and think himself acting unethically if he indulged in the voyeurism we term "Peeping Tom," but he feels perfectly fine and within appropriate boundaries to indulge in the viewing of pornography. Here by pornography I am largely referring to the cinematic kind.
But perhaps the typical person - and his culture at large - tend to arrive at the conclusion pornography is art and therefore qualitatively different from the "Peeping Tome" indulgence? Cinematic porn does after all make a claim to using actors and actresses, scripts, and theatrics.
But if pornography is indeed an art what kind of art is it, and are the effects positive or good? Can pornography when judged from a secular point of analysis even be an amoral or a-ethical issue?