xhonzi said:

I think the delted scene about the lost 24 seems to back you up here. Personally, I don't buy it. How could there not be Dark Jedi? How could there not be Dark Jedi in almost equal number to Light Jedi? It's the line that all Jedi must walk, right? Does the Force only speak to the pure in heart? If so, then there is no threat of Luke becoming Vader II (or III or IV or LXI) and you need some kind of convoluted reason for why Anakin fell.

If the Jedi can just as easily be bad as good, then it makes them a big X-factor for the normal citizens of the galaxy and it just might be easier if they all went away and the proverbial baby was thrown out with the proverbial bath water.

But that's what's in the OT. Vader being seduced by the dark side was a big deal, so it must be uncommon. Perhaps the Force does only speak to the pure of heart. It seems likely. Being "Strong in the Force" isn't just a random mutation, but perhaps a special calling.

What do we know about the jedi from the OT?

Guardians of Peace and Justice for a hecka long time.
Betrayed and Murdered by Darth Vader.
They begin training younger than their early 20s, apparently by Yoda or perhaps other Masters.
Anakin fell because he was angry and impatient. It is possible he was trained poorly and began too old.

If the Jedi can just as easily be good or bad, then they aren't Guardians of Peace and Justice in the Galaxy. They're just a bunch of people with superpowers.