Why did Saruman seem to believe that Sauron wouldn't return?

Question

In The Hobbit: An Unexpected Journey, when Gandalf is meeting with Saruman, Galadriel and Elrond in Rivendell, they are discussing the Necromancer. When Gandalf suggests that it is Sauron returning, Saruman insists that it's impossible and Sauron cannot and will not return.

The Istari (the wizards on Middle-earth) were sent back specifically to prevent the return of Sauron, so why would Saruman insist that it was impossible? Surely at least he'd investigate further to refute it.

I'm reasonably prepared to accept the answer "Jackson. 'Nuff said", although it'd be nice if there was another reason.

Edit: I found this related, but not duplicate quesion, as it doesn't address why he wouldn't check further

Answer 1

There's certainly an element of "Jackson, 'nuff said" in it - in the books the Wise (Eldar and Istari) had begun to suspect that the power in Dol Guldur was Sauron by TA2060 (approx. 900 years before the events of the Hobbit) and knew it for certain by TA2850 (approx. 100 years before the events of the Hobbit).

However, it is broadly accurate to Saruman's behaviour in the books, where it's documented that Saruman opposed any action against Dol Guldur. All of this is documented in the Lord of the Rings chapter the Council of Elrond:

Some, too, will remember also that Saruman dissuaded us from open deeds against him, and for long we watched him only.

And also that he had argued to the Council that Sauron's Ring would never be found again (and therefore Sauron could never be a potent force for evil again):

"At the worst," said he, "our Enemy knows that we have it not and that it still is lost. But what was lost may yet be found, he thinks. Fear not! His hope will cheat him. Have I not earnestly studied this matter? Into Anduin the Great it fell; and long ago, while Sauron slept, it was rolled down the River to the Sea. There let it lie until the End."

Eventually Saruman yielded and agreed to an assault on Dol Guldur, but it was only after discovering that Sauron's servants were also searching the Gladden Fields for the Ring. This is told in the Tale of Years for the Third Age:

2939: Saruman discovers that Sauron's servants are searching the Anduin near Gladden Fields, and that Sauron therefore has learned of Isildur's end. He is alarmed, but says nothing to the Council.

The assualt on Dol Guldur, and other events of the Hobbit, then took place in TA2941, two years after that.

Footnote 55 (on the entry or TA2851) to the Tale of Years finally makes Saruman's motive explicit:

It afterwards became clear that Saruman had then begun to desire to possess the One Ring himself, and he hoped that it might reveal itself, seeking its master, if Sauron were let be for a time.

So it's therefore clear that Saruman wanted to leave Sauron alone so that the Ring might reveal itself, but it was only after the danger of Sauron finding it first became real that he finally consented.

Answer 2

My idea when watching this scene was that it was basically a foreshadowing of Saruman's future treachery. Though he was still very loyal to the anti-Sauron side of things at this point, it's possible that some small part of his mind was already starting to tend in a pro-Sauron direction, therefore perhaps a subtle and even unconscious desire not to investigate and therefore possibly endanger Sauron as he is just beginning to rebuild his strength. To the audience it seems rather obvious that the Necromancer is really Sauron. I am reminded of Star Wars, where it is also rather obvious to most of the audience that Darth Sidious, Senator Palpatine, and the Emperor are all one and the same, but to the other characters in the story, this is a huge secret which would vastly alter the plot if known!

Answer 3

If you cross reference several of the books it becomes clear that Saruman at that time was already under Saurons influence. He always had the stone of Orthanc (the Palantír) since that belongs in Orthanc to begin with (see the Silmarillion) so it's highly likely that wether knowingly or unknowlingly he was already caught in the web.

Denethor too has a Palantír which, again, is how he fell under Saurons influence.

All Palantír were corrupted long before The Hobbit even started. So in my opinion Saruman was already in league with Sauron (and/or trying to take the ring for himself) at that time. This is supported by the Ents anger, Saruman hasn't been creating an army for a short time to anger the Ents thus, the wanton destruction of the forest of Fangorn has been going on for a long timespan by Ent accounts and Ents get pretty close to immortality.

Finally he couldn't have built an army that size that fast, he would have to have already been at it for a long time, not just creating the uruk-hai, but also the trial and error it takes to get the crossbreed just right, as is evidenced by the extremely good combination of orc ferocity and human cunning.

If I'm not mistaken both Gandalf and Galadriel are suspicious of Saruman in that meeting to begin with,