How would the destruction of the Sith bring balance to the Force?

[Al]

It seems to be that for there to be balance you need both sides. If the Sith were destroyed, how would that mean there was balance in the Force?

 

[Darth Cognus]

The balance as far as I'm concerned is not an equal dichotomy, ie, there must be 2 sith lords and 2 jedi masters or whatever. Rather I would put it this way; the force is a nature that simply is. The dark side is its selfish perversion, excesses, unchecked pursuit of power. Not supernatural, in fact, quite natural mortal vices which are simply accelerated by space magic. Conversely the light represents the opposition of attempts to throw the force utterly out of whack with destruction, with selflessness, virtue and other commonly recognized boons complimenting the effort. The light is a natural state of continued existence, the dark represents a nature that cannot truly be extinguished, but must always be controlled. The Jedi are a religious order based on this effort, and until the deaths of Vader and Palpatine, the Sith were a nearly just as old religious/political entity built on embracing vices with just enough control to try and dominate the galaxy. But in the end it was always self defeating.

It's all point of view and you shouldn't take my word for it, so I'll quote highlights from a few neat reads.

By John F. Trent at Bounding into Comics, here, these are key highlights:

This idea that the Force is in balance when the Light Side and the Dark Side are on equal footing likely comes from watching Star Wars: The Clone Wars and specifically the Mortis trilogy episodes created by Dave Filoni.

This is where most confusion appears - Filoni wrote episodes that oversimplified the moral (as far as I've understood it) and so encouraged the idea that the two were things to embrace in equal measure, when that isn't necessarily ideal. It's why I don't care for the Grey Jedi business but more on that in another thread soon.

George says quite a bit, see the video on youtube for his full statements, but it's summed up with this:

“The only way to overcome the Dark Side is through discipline. The Dark Side is pleasure, biological, and temporary, and easy to achieve.”

“The Light Side is joy, everlasting, and difficult to achieve. A great challenge. Must overcome laziness, give up quick pleasures, and overcome fear which leads to hate,”

The Dark Side in other words is taking the easy way out, and while it is infinitely effective in the short term its long term conclusion is inevitably unsatisfying. This is the state of mind that the balance was originally written from and is the strongest explanation you can get I think, but here is an analogy coming to a similar conclusion from Reddit:

Here's how the force works. The force is a valley. The galaxy is part of that valley. The dark side is the river that runs through it, and the light side is the river bank.
The valley would decay and die without the river. But when the river overruns the riverbank, it floods and destroys the valley. The riverbank needs must be strong so as to not permit the river from overflowing. It will never destory the river, no matter how strong. It'll only protect the valley.
So while the Jedi can be a stand in for the light and the riverbank, the Sith are not the river. Rather, they are trying to destroy the riverbank so that it may flood the river.
The Sith are not the dark side. The Sith are using the dark side to pervert the valley. Darkness, like the river, is not intrinsically bad. In fact, it's even necessary for the valley's health. But using the darkness to overflow the river and destroy the valley is evil.
That's why bringing balance to the force requires their destruction.

The idea of there being another thing called 'balance' in the middle is not uncommon even in official media but I consider it a modern perversion of the story originally being told, by authors who've made up their own thing. If we accept that then it's time to embrace Kreia as prophet of the force itself being a meddling malevolence that only exists to create conflict for the fun of it.

 

[Bizdustry]

The force has been tainted by the dark side. Individuals are bound to be upset, depressed, or nervous; it cannot be totally eradicated, but as long as it keeps from from festering, spreading, and gaining control over the galaxy, everything will be OK.

By ruining them, the Sith hope to restore equalise to the power and use it to seize control of the galactic system.

 

[Debashis]

By eliminating the Sith, the dominant dark side force, the balance between the light and dark sides of the Force would be restored. This would enable the Force to exist in harmony, without the corrupting influence of the Sith's power and malevolence.