Our Ability to Use the Force Has Diminished: what does it me

[Stark]

The Jedi refusal to do something does not translate to 'saving a woman from dying for basically no reason' is a dark side only power.

Next we'll hear 'leaving Anakin's mother to die' is a dark side power!

[Darth Klingon]

The Jedi refusal to do something does not translate to 'saving a woman from dying for basically no reason' is a dark side only power.

Next we'll hear 'leaving Anakin's mother to die' is a dark side power!

In the EU, it mentions that part of the reason why Anakin was angry at the Jedi Council for not making him a Master was because Jedi Masters had access to secret information to save people from death. The Jedi used the lightside, not the darkside.

So, there were some lightside powers to stop death. It wasn't just something that the Sith had.

[Arawn Fenn]

The Jedi refusal to do something does not translate to 'saving a woman from dying for basically no reason' is a dark side only power.

And why would the Jedi refuse to do something that could be used to save the dying?

Palpatine is credible when alluding to dark side only powers because in his thirteen years of training as a Jedi Anakin has never been told that dark side only powers cannot exist. In fact, quite the opposite, given that he has already been on the receiving end of one.

[Darth Klingon]

The assumption that it is possible for the dark side to provide unique powers is also central to the seduction of Anakin plotline in ROTS.

Palpatine was lying to Anakin. In the Rise and Fall of Darth Vader, it mentions that he didn't know how to use Plagueis's power.

[Broken]

As for the Force being dual-aspected or not, I refer to this quote from Lucas

MOYERS: When Darth Vader tempts Luke to come over to the Empire side, offering him all that the Empire has to offer, I am taken back to the story of Satan taking Christ to the mountain and offering him the kingdoms of the world, if only he will turn away from his mission. Was that conscious in your mind?
LUCAS: Yes. That story also has been retold. Buddha was tempted in the same way. It's all through mythology. The gods are constantly tempting. Everybody and everything. So the idea of temptation is one of the things we struggle against, and the temptation obviously is the temptation to go to the dark side. One of the themes throughout the films is that the Sith lords, when they started out thousands of years ago, embraced the dark side. They were greedy and self-centered and they all wanted to take over, so they killed each other. Eventually, there was only one left, and that one took on an apprentice. And for thousands of years, the master would teach the apprentice, the master would die, the apprentice would then teach another apprentice, become the master, and so on. But there could never be any more than two of them, because if there were, they would try to get rid of the leader, which is exactly what Vader was trying to do, and that's exactly what the Emperor was trying to do. The Emperor was trying to get rid of Vader, and Vader was trying to get rid of the Emperor. And that is the antithesis of a symbiotic relationship, in which if you do that, you become cancer, and you eventually kill the host, and everything dies.
interview between George Lucas and Bill Moyer, published in Time April 26, 1999

If you embrace the Dark Side, you begin to act like a cancer. Since a normal body does not require a balance of healthy cells and cancer cells, I would not say the Dark Side is surely not the equal/opposite of the fictional light side (as has been pointed out repeatedly, a term NEVER used in the movies) but a blight upon the Force.

[Kreller1]

And why would the Jedi refuse to do something that could be used to save the dying?

In Anakin's case, the fact that he has attachment issues with his mother means the last thing the Council wants is for Anakin to go run off and save her life. It would go completely against the Code. This is assuming that they truly do know how to save a life without tapping the Dark side to do so, which would be a major no-no for any Jedi. (Especially in the Council's eyes.)

[Arawn Fenn]

Palpatine was lying to Anakin. In the Rise and Fall of Darth Vader, it mentions that he didn't know how to use Plagueis's power.

He didn't say he knew how to use Plagueis' power. In fact, that he didn't was part of what he told Anakin. The point was that Plagueis knew how to use Plagueis' power, which was confirmed in Darth Plagueis when Palpatine saw it with his own eyes.

[Arawn Fenn]

As for the Force being dual-aspected or not, I refer to this quote from Lucas

Except that quote doesn't actually discuss the structure of the Force ( i.o.w., the Force being dual-aspected or not ). It merely describes the Sith as having a relationship which is cancerous in nature. This is the quote which somehow compels revisionists to claim "Lucas said the dark side is a cancer", but as anyone can see for themselves by inspecting the quote, it says no such thing. In other quotes Lucas has repeatedly stated that the Force has two sides, and has said that they both need to be there. People seem to forget that the balance of the Force plotline rests on the Force's having sides, so one of the things you would have to do in order to get rid of the sides of the Force would be to throw out the PT. But don't get excited - the OT would have to go too. We've known the Force had sides ever since Alec Guinness spoke of the dark side of the Force in 1977. On Dagobah we heard of the good side and the bad side. The Force has been dual-aspected since day one.

the fictional light side (as has been pointed out repeatedly, a term NEVER used in the movies)

It was called the "good side" in the movies. Its existence is unavoidable if one concedes that the dark side is not the entirety of the Force. In mathematical terms L = LF - D. Both Lucas and his characters have spoken of it. It doesn't magically cease to exist by virtue of having been colloquially renamed after the OT. By that logic Qui-Gon's lightsaber became "fictional" as soon as Anakin called it a laser sword. Renaming things does not nullify their existence; that is not how reality works.